[PATCH 0/9] in-kernel APIC v5 (kernel side)

[PATCH 0/9] in-kernel APIC v5 (kernel side)

[Gregory Haskins]

This is rapidly converging, so sorry for the v4 and v5 posts back to back.  I
am now running through the test matrix as proposed by Avi.

v5 builds upon v4 by adding:

1) Incorporated general minor feedback
2) Big change is vcpu->irq.task is now "pid_t vcpu->owner" to eliminate
   potential dangling task pointer issue.

As before, I have tested 32 bit XP w/ACPI and 64 bit linux.

Regards,
-Greg


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[PATCH 1/9] KVM: Adds support for in-kernel mmio handlers

[Gregory Haskins]

Signed-off-by: Gregory Haskins <ghaskins-Et1tbQHTxzrQT0dZR+AlfA@public.gmane.org>
---

 drivers/kvm/kvm.h      |   60 +++++++++++++++++++++++++++++++
 drivers/kvm/kvm_main.c |   94 ++++++++++++++++++++++++++++++++++++++++++------
 2 files changed, 142 insertions(+), 12 deletions(-)

diff --git a/drivers/kvm/kvm.h b/drivers/kvm/kvm.h
index 1bbafba..e32f63a 100644
--- a/drivers/kvm/kvm.h
+++ b/drivers/kvm/kvm.h
@@ -256,6 +256,65 @@ struct kvm_stat {
 	u32 light_exits;
 };
 
+struct kvm_io_device {
+	void (*read)(struct kvm_io_device *this,
+		     gpa_t addr,
+		     int len,
+		     void *val);
+	void (*write)(struct kvm_io_device *this,
+		      gpa_t addr,
+		      int len,
+		      const void *val);
+	int (*in_range)(struct kvm_io_device *this, gpa_t addr);
+	void (*destructor)(struct kvm_io_device *this);
+
+	void             *private;
+};
+
+static inline void kvm_iodevice_read(struct kvm_io_device *dev,
+				     gpa_t addr,
+				     int len,
+				     void *val)
+{
+	dev->read(dev, addr, len, val);
+}
+
+static inline void kvm_iodevice_write(struct kvm_io_device *dev,
+				      gpa_t addr,
+				      int len,
+				      const void *val)
+{
+	dev->write(dev, addr, len, val);
+}
+
+static inline int kvm_iodevice_inrange(struct kvm_io_device *dev, gpa_t addr)
+{
+	return dev->in_range(dev, addr);
+}
+
+static inline void kvm_iodevice_destructor(struct kvm_io_device *dev)
+{
+	dev->destructor(dev);
+}
+
+/*
+ * It would be nice to use something smarter than a linear search, TBD...
+ * Thankfully we dont expect many devices to register (famous last words :),
+ * so until then it will suffice.  At least its abstracted so we can change
+ * in one place.
+ */
+struct kvm_io_bus {
+	int                   dev_count;
+#define NR_IOBUS_DEVS 6
+	struct kvm_io_device *devs[NR_IOBUS_DEVS];
+};
+
+void kvm_io_bus_init(struct kvm_io_bus *bus);
+void kvm_io_bus_destroy(struct kvm_io_bus *bus);
+struct kvm_io_device *kvm_io_bus_find_dev(struct kvm_io_bus *bus, gpa_t addr);
+void kvm_io_bus_register_dev(struct kvm_io_bus *bus,
+			     struct kvm_io_device *dev);
+
 struct kvm_vcpu {
 	struct kvm *kvm;
 	union {
@@ -375,6 +434,7 @@ struct kvm {
 	unsigned long rmap_overflow;
 	struct list_head vm_list;
 	struct file *filp;
+	struct kvm_io_bus mmio_bus;
 };
 
 struct descriptor_table {
diff --git a/drivers/kvm/kvm_main.c b/drivers/kvm/kvm_main.c
index 1288cff..6ff30a2 100644
--- a/drivers/kvm/kvm_main.c
+++ b/drivers/kvm/kvm_main.c
@@ -317,6 +317,7 @@ static struct kvm *kvm_create_vm(void)
 
 	spin_lock_init(&kvm->lock);
 	INIT_LIST_HEAD(&kvm->active_mmu_pages);
+	kvm_io_bus_init(&kvm->mmio_bus);
 	for (i = 0; i < KVM_MAX_VCPUS; ++i) {
 		struct kvm_vcpu *vcpu = &kvm->vcpus[i];
 
@@ -414,6 +415,7 @@ static void kvm_destroy_vm(struct kvm *kvm)
 	spin_lock(&kvm_lock);
 	list_del(&kvm->vm_list);
 	spin_unlock(&kvm_lock);
+	kvm_io_bus_destroy(&kvm->mmio_bus);
 	kvm_free_vcpus(kvm);
 	kvm_free_physmem(kvm);
 	kfree(kvm);
@@ -1037,12 +1039,25 @@ static int emulator_write_std(unsigned long addr,
 	return X86EMUL_UNHANDLEABLE;
 }
 
+static struct kvm_io_device *vcpu_find_mmio_dev(struct kvm_vcpu *vcpu,
+						gpa_t addr)
+{
+	/*
+	 * Note that its important to have this wrapper function because
+	 * in the very near future we will be checking for MMIOs against
+	 * the LAPIC as well as the general MMIO bus
+	 */
+	return kvm_io_bus_find_dev(&vcpu->kvm->mmio_bus, addr);
+}
+
 static int emulator_read_emulated(unsigned long addr,
 				  void *val,
 				  unsigned int bytes,
 				  struct x86_emulate_ctxt *ctxt)
 {
-	struct kvm_vcpu *vcpu = ctxt->vcpu;
+	struct kvm_vcpu      *vcpu = ctxt->vcpu;
+	struct kvm_io_device *mmio_dev;
+	gpa_t                 gpa;
 
 	if (vcpu->mmio_read_completed) {
 		memcpy(val, vcpu->mmio_data, bytes);
@@ -1051,18 +1066,26 @@ static int emulator_read_emulated(unsigned long addr,
 	} else if (emulator_read_std(addr, val, bytes, ctxt)
 		   == X86EMUL_CONTINUE)
 		return X86EMUL_CONTINUE;
-	else {
-		gpa_t gpa = vcpu->mmu.gva_to_gpa(vcpu, addr);
 
-		if (gpa == UNMAPPED_GVA)
-			return X86EMUL_PROPAGATE_FAULT;
-		vcpu->mmio_needed = 1;
-		vcpu->mmio_phys_addr = gpa;
-		vcpu->mmio_size = bytes;
-		vcpu->mmio_is_write = 0;
+	gpa = vcpu->mmu.gva_to_gpa(vcpu, addr);
+	if (gpa == UNMAPPED_GVA)
+		return X86EMUL_PROPAGATE_FAULT;
 
-		return X86EMUL_UNHANDLEABLE;
+	/*
+	 * Is this MMIO handled locally?
+	 */
+	mmio_dev = vcpu_find_mmio_dev(vcpu, gpa);
+	if (mmio_dev) {
+		kvm_iodevice_read(mmio_dev, gpa, bytes, val);
+		return X86EMUL_CONTINUE;
 	}
+
+	vcpu->mmio_needed = 1;
+	vcpu->mmio_phys_addr = gpa;
+	vcpu->mmio_size = bytes;
+	vcpu->mmio_is_write = 0;
+
+	return X86EMUL_UNHANDLEABLE;
 }
 
 static int emulator_write_phys(struct kvm_vcpu *vcpu, gpa_t gpa,
@@ -1090,8 +1113,9 @@ static int emulator_write_emulated(unsigned long addr,
 				   unsigned int bytes,
 				   struct x86_emulate_ctxt *ctxt)
 {
-	struct kvm_vcpu *vcpu = ctxt->vcpu;
-	gpa_t gpa = vcpu->mmu.gva_to_gpa(vcpu, addr);
+	struct kvm_vcpu      *vcpu = ctxt->vcpu;
+	struct kvm_io_device *mmio_dev;
+	gpa_t                 gpa = vcpu->mmu.gva_to_gpa(vcpu, addr);
 
 	if (gpa == UNMAPPED_GVA) {
 		kvm_arch_ops->inject_page_fault(vcpu, addr, 2);
@@ -1101,6 +1125,15 @@ static int emulator_write_emulated(unsigned long addr,
 	if (emulator_write_phys(vcpu, gpa, val, bytes))
 		return X86EMUL_CONTINUE;
 
+	/*
+	 * Is this MMIO handled locally?
+	 */
+	mmio_dev = vcpu_find_mmio_dev(vcpu, gpa);
+	if (mmio_dev) {
+		kvm_iodevice_write(mmio_dev, gpa, bytes, val);
+		return X86EMUL_CONTINUE;
+	}
+
 	vcpu->mmio_needed = 1;
 	vcpu->mmio_phys_addr = gpa;
 	vcpu->mmio_size = bytes;
@@ -2933,6 +2966,43 @@ static int kvm_cpu_hotplug(struct notifier_block *notifier, unsigned long val,
 	return NOTIFY_OK;
 }
 
+void kvm_io_bus_init(struct kvm_io_bus *bus)
+{
+	memset(bus, 0, sizeof(*bus));
+}
+
+void kvm_io_bus_destroy(struct kvm_io_bus *bus)
+{
+	int i;
+
+	for (i = 0; i < bus->dev_count; i++) {
+		struct kvm_io_device *pos = bus->devs[i];
+
+		kvm_iodevice_destructor(pos);
+	}
+}
+
+struct kvm_io_device *kvm_io_bus_find_dev(struct kvm_io_bus *bus, gpa_t addr)
+{
+	int i;
+
+	for (i = 0; i < bus->dev_count; i++) {
+		struct kvm_io_device *pos = bus->devs[i];
+
+		if (pos->in_range(pos, addr))
+			return pos;
+	}
+
+	return NULL;
+}
+
+void kvm_io_bus_register_dev(struct kvm_io_bus *bus, struct kvm_io_device *dev)
+{
+	BUG_ON(bus->dev_count > (NR_IOBUS_DEVS-1));
+
+	bus->devs[bus->dev_count++] = dev;
+}
+
 static struct notifier_block kvm_cpu_notifier = {
 	.notifier_call = kvm_cpu_hotplug,
 	.priority = 20, /* must be > scheduler priority */


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[PATCH 2/9] KVM: VMX - fix interrupt checking on light-exit

[Gregory Haskins]

Signed-off-by: Gregory Haskins <ghaskins-Et1tbQHTxzrQT0dZR+AlfA@public.gmane.org>
---

 drivers/kvm/vmx.c |    6 +++---
 1 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/kvm/vmx.c b/drivers/kvm/vmx.c
index 804a623..e696d02 100644
--- a/drivers/kvm/vmx.c
+++ b/drivers/kvm/vmx.c
@@ -1934,13 +1934,13 @@ static int vmx_vcpu_run(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
 	int r;
 
 preempted:
-	if (!vcpu->mmio_read_completed)
-		do_interrupt_requests(vcpu, kvm_run);
-
 	if (vcpu->guest_debug.enabled)
 		kvm_guest_debug_pre(vcpu);
 
 again:
+	if (!vcpu->mmio_read_completed)
+		do_interrupt_requests(vcpu, kvm_run);
+
 	vmx_save_host_state(vcpu);
 	kvm_load_guest_fpu(vcpu);
 


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[PATCH 3/9] KVM: Add irqdevice object

[Gregory Haskins]

The current code is geared towards using a user-mode (A)PIC.  This patch adds
an "irqdevice" abstraction, and implements a "userint" model to handle the
duties of the original code.  Later, we can develop other irqdevice models
to handle objects like LAPIC, IOAPIC, i8259, etc, as appropriate

Signed-off-by: Gregory Haskins <ghaskins-Et1tbQHTxzrQT0dZR+AlfA@public.gmane.org>
---

 drivers/kvm/Makefile    |    2 
 drivers/kvm/irqdevice.h |  176 +++++++++++++++++++++++++++++++++++++
 drivers/kvm/kvm.h       |  107 ++++++++++++++++++++++-
 drivers/kvm/kvm_main.c  |   58 +++++++++---
 drivers/kvm/svm.c       |  162 ++++++++++++++++++++++++----------
 drivers/kvm/userint.c   |  223 +++++++++++++++++++++++++++++++++++++++++++++++
 drivers/kvm/vmx.c       |  161 +++++++++++++++++++++++++---------
 7 files changed, 782 insertions(+), 107 deletions(-)

diff --git a/drivers/kvm/Makefile b/drivers/kvm/Makefile
index c0a789f..540afbc 100644
--- a/drivers/kvm/Makefile
+++ b/drivers/kvm/Makefile
@@ -2,7 +2,7 @@
 # Makefile for Kernel-based Virtual Machine module
 #
 
-kvm-objs := kvm_main.o mmu.o x86_emulate.o
+kvm-objs := kvm_main.o mmu.o x86_emulate.o userint.o
 obj-$(CONFIG_KVM) += kvm.o
 kvm-intel-objs = vmx.o
 obj-$(CONFIG_KVM_INTEL) += kvm-intel.o
diff --git a/drivers/kvm/irqdevice.h b/drivers/kvm/irqdevice.h
new file mode 100644
index 0000000..097d179
--- /dev/null
+++ b/drivers/kvm/irqdevice.h
@@ -0,0 +1,176 @@
+/*
+ * Defines an interface for an abstract interrupt controller.  The model
+ * consists of a unit with an arbitrary number of input lines N (IRQ0-(N-1)),
+ * an arbitrary number of output lines (INTR) (LINT, EXTINT, NMI, etc), and
+ * methods for completing an interrupt-acknowledge cycle (INTA).  A particular
+ * implementation of this model will define various policies, such as
+ * irq-to-vector translation, INTA/auto-EOI policy, etc.
+ *
+ * In addition, the INTR callback mechanism allows the unit to be "wired" to
+ * an interruptible source in a very flexible manner. For instance, an
+ * irqdevice could have its INTR wired to a VCPU (ala LAPIC), or another
+ * interrupt controller (ala cascaded i8259s)
+ *
+ * Copyright (C) 2007 Novell
+ *
+ * Authors:
+ *   Gregory Haskins <ghaskins-Et1tbQHTxzrQT0dZR+AlfA@public.gmane.org>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2.  See
+ * the COPYING file in the top-level directory.
+ *
+ */
+
+#ifndef __IRQDEVICE_H
+#define __IRQDEVICE_H
+
+struct kvm_irqdevice;
+
+typedef enum {
+	kvm_irqpin_localint,
+	kvm_irqpin_extint,
+	kvm_irqpin_smi,
+	kvm_irqpin_nmi,
+	kvm_irqpin_invalid, /* must always be last */
+} kvm_irqpin_t;
+
+
+struct kvm_irqsink {
+	void (*set_intr)(struct kvm_irqsink *this,
+			 struct kvm_irqdevice *dev,
+			 kvm_irqpin_t pin);
+
+	void *private;
+};
+
+#define KVM_IRQACKDATA_VECTOR_VALID   (1 << 0)
+#define KVM_IRQACKDATA_VECTOR_PENDING (1 << 1)
+
+#define KVM_IRQACK_FLAG_PEEK          (1 << 0)
+
+struct kvm_irqack_data {
+	int flags;
+	int vector;
+};
+
+struct kvm_irqdevice {
+	int  (*ack)(struct kvm_irqdevice *this, int flags,
+		    struct kvm_irqack_data *data);
+	int  (*set_pin)(struct kvm_irqdevice *this, int pin, int level);
+	void (*destructor)(struct kvm_irqdevice *this);
+
+	void               *private;
+	struct kvm_irqsink  sink;
+};
+
+/**
+ * kvm_irqdevice_init - initialize the kvm_irqdevice for use
+ * @dev: The device
+ *
+ * Description: Initialize the kvm_irqdevice for use.  Should be called before
+ *              calling any derived implementation init functions
+ *
+ * Returns: (void)
+ */
+static inline void kvm_irqdevice_init(struct kvm_irqdevice *dev)
+{
+	memset(dev, 0, sizeof(*dev));
+}
+
+/**
+ * kvm_irqdevice_ack - read and ack the highest priority vector from the device
+ * @dev: The device
+ * @flags: Modifies default behavior
+ *           [ KVM_IRQACK_FLAG_PEEK - Dont ack vector, just check status ]
+ * @data: A pointer to a kvm_irqack_data structure to hold the result
+ *
+ * Description: Read the highest priority pending vector from the device,
+ *              potentially invoking auto-EOI depending on device policy
+ *
+ *              Successful return indicates that the *data* structure is valid
+ *
+ *               data.flags -
+ *                  [KVM_IRQACKDATA_VECTOR_VALID - data.vector is valid]
+ *                  [KVM_IRQACKDATA_VECTOR_PENDING - more vectors are pending]
+ *
+ * Returns: (int)
+ *   [-1 = failure]
+ *   [ 0 = success]
+ */
+static inline int kvm_irqdevice_ack(struct kvm_irqdevice *dev, int flags,
+				    struct kvm_irqack_data *data)
+{
+	return dev->ack(dev, flags, data);
+}
+
+/**
+ * kvm_irqdevice_set_pin - allows the caller to assert/deassert an IRQ
+ * @dev: The device
+ * @pin: The input pin to alter
+ * @level: The value to set (1 = assert, 0 = deassert)
+ *
+ * Description: Allows the caller to assert/deassert an IRQ input pin to the
+ *              device according to device policy.
+ *
+ * Returns: (int)
+ *   [-1 = failure]
+ *   [ 0 = success]
+ */
+static inline int kvm_irqdevice_set_pin(struct kvm_irqdevice *dev, int pin,
+				  int level)
+{
+	return dev->set_pin(dev, pin, level);
+}
+
+/**
+ * kvm_irqdevice_register_sink - registers an kvm_irqsink object
+ * @dev: The device
+ * @sink: The sink to register.  Data will be copied so building object from
+ *        transient storage is ok.
+ *
+ * Description: Registers an kvm_irqsink object as an INTR callback
+ *
+ * Returns: (void)
+ */
+static inline void kvm_irqdevice_register_sink(struct kvm_irqdevice *dev,
+					       const struct kvm_irqsink *sink)
+{
+	dev->sink = *sink;
+}
+
+/**
+ * kvm_irqdevice_destructor - destroys an irqdevice
+ * @dev: The device
+ *
+ * Returns: (void)
+ */
+static inline void kvm_irqdevice_destructor(struct kvm_irqdevice *dev)
+{
+	dev->destructor(dev);
+}
+
+/**
+ * kvm_irqdevice_set_intr - invokes a registered INTR callback
+ * @dev: The device
+ * @pin: Identifies the pin to alter -
+ *           [ KVM_IRQPIN_LOCALINT (default) - an vector is pending on this
+ *                                             device]
+ *           [ KVM_IRQPIN_EXTINT - a vector is pending on an external device]
+ *           [ KVM_IRQPIN_SMI - system-management-interrupt pin]
+ *           [ KVM_IRQPIN_NMI - non-maskable-interrupt pin
+ *
+ * Description: Invokes a registered INTR callback (if present).  This
+ *              function is meant to be used privately by a irqdevice
+ *              implementation.
+ *
+ * Returns: (void)
+ */
+static inline void kvm_irqdevice_set_intr(struct kvm_irqdevice *dev,
+					  kvm_irqpin_t pin)
+{
+	struct kvm_irqsink *sink = &dev->sink;
+	if (sink->set_intr)
+		sink->set_intr(sink, dev, pin);
+}
+
+#endif /*  __IRQDEVICE_H */
diff --git a/drivers/kvm/kvm.h b/drivers/kvm/kvm.h
index e32f63a..41e4eaa 100644
--- a/drivers/kvm/kvm.h
+++ b/drivers/kvm/kvm.h
@@ -13,6 +13,7 @@
 #include <linux/mm.h>
 
 #include "vmx.h"
+#include "irqdevice.h"
 #include <linux/kvm.h>
 #include <linux/kvm_para.h>
 
@@ -160,6 +161,11 @@ struct vmcs {
 
 struct kvm_vcpu;
 
+int kvm_user_irqdev_init(struct kvm_irqdevice *dev);
+int kvm_user_irqdev_save(struct kvm_irqdevice *this, void *data);
+int kvm_user_irqdev_restore(struct kvm_irqdevice *this, void *data);
+int kvm_userint_init(struct kvm_vcpu *vcpu);
+
 /*
  * x86 supports 3 paging modes (4-level 64-bit, 3-level 64-bit, and 2-level
  * 32-bit).  The kvm_mmu structure abstracts the details of the current mmu
@@ -315,6 +321,18 @@ struct kvm_io_device *kvm_io_bus_find_dev(struct kvm_io_bus *bus, gpa_t addr);
 void kvm_io_bus_register_dev(struct kvm_io_bus *bus,
 			     struct kvm_io_device *dev);
 
+#define NR_IRQ_WORDS KVM_IRQ_BITMAP_SIZE(unsigned long)
+
+/*
+ * structure for maintaining info for interrupting an executing VCPU
+ */
+struct kvm_vcpu_irq {
+	spinlock_t           lock;
+	struct kvm_irqdevice dev;
+	int                  pending;
+	int                  deferred;
+};
+
 struct kvm_vcpu {
 	struct kvm *kvm;
 	union {
@@ -327,9 +345,7 @@ struct kvm_vcpu {
 	u64 host_tsc;
 	struct kvm_run *run;
 	int interrupt_window_open;
-	unsigned long irq_summary; /* bit vector: 1 per word in irq_pending */
-#define NR_IRQ_WORDS KVM_IRQ_BITMAP_SIZE(unsigned long)
-	unsigned long irq_pending[NR_IRQ_WORDS];
+	struct kvm_vcpu_irq irq;
 	unsigned long regs[NR_VCPU_REGS]; /* for rsp: vcpu_load_rsp_rip() */
 	unsigned long rip;      /* needs vcpu_load_rsp_rip() */
 
@@ -402,6 +418,91 @@ struct kvm_vcpu {
 	struct kvm_cpuid_entry cpuid_entries[KVM_MAX_CPUID_ENTRIES];
 };
 
+/*
+ * Assumes lock already held
+ */
+static inline int __kvm_vcpu_irq_all_pending(struct kvm_vcpu *vcpu)
+{
+	int pending = vcpu->irq.pending;
+
+	if (vcpu->irq.deferred != -1)
+		__set_bit(kvm_irqpin_localint, &pending);
+
+	return pending;
+}
+
+/*
+ * These two functions are helpers for determining if a standard interrupt
+ * is pending to replace the old "if (vcpu->irq_summary)" logic.  If the
+ * caller wants to know about some of the new advanced interrupt types
+ * (SMI, NMI, etc) or to differentiate between localint and extint they will
+ *  have to use the new API
+ */
+static inline int __kvm_vcpu_irq_pending(struct kvm_vcpu *vcpu)
+{
+	int pending = __kvm_vcpu_irq_all_pending(vcpu);
+
+	if (test_bit(kvm_irqpin_localint, &pending) ||
+	    test_bit(kvm_irqpin_extint, &pending))
+		return 1;
+
+	return 0;
+}
+
+static inline int kvm_vcpu_irq_pending(struct kvm_vcpu *vcpu)
+{
+	int ret = 0;
+	int flags;
+
+	spin_lock_irqsave(&vcpu->irq.lock, flags);
+	ret = __kvm_vcpu_irq_pending(vcpu);
+	spin_unlock_irqrestore(&vcpu->irq.lock, flags);
+
+	return ret;
+}
+
+/*
+ * Assumes lock already held
+ */
+static inline int kvm_vcpu_irq_pop(struct kvm_vcpu *vcpu,
+				   struct kvm_irqack_data *data)
+{
+	int ret = 0;
+
+	if (vcpu->irq.deferred != -1) {
+		ret = kvm_irqdevice_ack(&vcpu->irq.dev, KVM_IRQACK_FLAG_PEEK,
+					data);
+		data->flags |= KVM_IRQACKDATA_VECTOR_VALID;
+		data->vector = vcpu->irq.deferred;
+		vcpu->irq.deferred = -1;
+	} else
+		ret = kvm_irqdevice_ack(&vcpu->irq.dev, 0, data);
+
+	/*
+	 * If there are no more interrupts we must clear the status flag
+	 */
+	if (!(data->flags & KVM_IRQACKDATA_VECTOR_PENDING))
+		__clear_bit(kvm_irqpin_localint, &vcpu->irq.pending);
+
+	return ret;
+}
+
+static inline void __kvm_vcpu_irq_push(struct kvm_vcpu *vcpu, int irq)
+{
+	BUG_ON(vcpu->irq.deferred != -1); /* We can only hold one deferred */
+
+	vcpu->irq.deferred = irq;
+}
+
+static inline void kvm_vcpu_irq_push(struct kvm_vcpu *vcpu, int irq)
+{
+	int flags;
+
+	spin_lock_irqsave(&vcpu->irq.lock, flags);
+	__kvm_vcpu_irq_push(vcpu, irq);
+	spin_unlock_irqrestore(&vcpu->irq.lock, flags);
+}
+
 struct kvm_mem_alias {
 	gfn_t base_gfn;
 	unsigned long npages;
diff --git a/drivers/kvm/kvm_main.c b/drivers/kvm/kvm_main.c
index 6ff30a2..a2e1e50 100644
--- a/drivers/kvm/kvm_main.c
+++ b/drivers/kvm/kvm_main.c
@@ -322,6 +322,11 @@ static struct kvm *kvm_create_vm(void)
 		struct kvm_vcpu *vcpu = &kvm->vcpus[i];
 
 		mutex_init(&vcpu->mutex);
+
+		memset(&vcpu->irq, 0, sizeof(vcpu->irq));
+		spin_lock_init(&vcpu->irq.lock);
+		vcpu->irq.deferred = -1;
+
 		vcpu->cpu = -1;
 		vcpu->kvm = kvm;
 		vcpu->mmu.root_hpa = INVALID_PAGE;
@@ -389,6 +394,7 @@ static void kvm_free_vcpu(struct kvm_vcpu *vcpu)
 	vcpu_load(vcpu);
 	kvm_mmu_destroy(vcpu);
 	vcpu_put(vcpu);
+	kvm_irqdevice_destructor(&vcpu->irq.dev);
 	kvm_arch_ops->vcpu_free(vcpu);
 	free_page((unsigned long)vcpu->run);
 	vcpu->run = NULL;
@@ -2008,8 +2014,7 @@ static int kvm_vcpu_ioctl_get_sregs(struct kvm_vcpu *vcpu,
 	sregs->efer = vcpu->shadow_efer;
 	sregs->apic_base = vcpu->apic_base;
 
-	memcpy(sregs->interrupt_bitmap, vcpu->irq_pending,
-	       sizeof sregs->interrupt_bitmap);
+	kvm_user_irqdev_save(&vcpu->irq.dev, &sregs->interrupt_bitmap);
 
 	vcpu_put(vcpu);
 
@@ -2026,7 +2031,6 @@ static int kvm_vcpu_ioctl_set_sregs(struct kvm_vcpu *vcpu,
 				    struct kvm_sregs *sregs)
 {
 	int mmu_reset_needed = 0;
-	int i;
 	struct descriptor_table dt;
 
 	vcpu_load(vcpu);
@@ -2063,12 +2067,8 @@ static int kvm_vcpu_ioctl_set_sregs(struct kvm_vcpu *vcpu,
 	if (mmu_reset_needed)
 		kvm_mmu_reset_context(vcpu);
 
-	memcpy(vcpu->irq_pending, sregs->interrupt_bitmap,
-	       sizeof vcpu->irq_pending);
-	vcpu->irq_summary = 0;
-	for (i = 0; i < NR_IRQ_WORDS; ++i)
-		if (vcpu->irq_pending[i])
-			__set_bit(i, &vcpu->irq_summary);
+	kvm_user_irqdev_restore(&vcpu->irq.dev,
+				&sregs->interrupt_bitmap[0]);
 
 	set_segment(vcpu, &sregs->cs, VCPU_SREG_CS);
 	set_segment(vcpu, &sregs->ds, VCPU_SREG_DS);
@@ -2229,14 +2229,8 @@ static int kvm_vcpu_ioctl_interrupt(struct kvm_vcpu *vcpu,
 {
 	if (irq->irq < 0 || irq->irq >= 256)
 		return -EINVAL;
-	vcpu_load(vcpu);
-
-	set_bit(irq->irq, vcpu->irq_pending);
-	set_bit(irq->irq / BITS_PER_LONG, &vcpu->irq_summary);
 
-	vcpu_put(vcpu);
-
-	return 0;
+	return kvm_irqdevice_set_pin(&vcpu->irq.dev, irq->irq, 1);
 }
 
 static int kvm_vcpu_ioctl_debug_guest(struct kvm_vcpu *vcpu,
@@ -2338,6 +2332,32 @@ out1:
 }
 
 /*
+ * This function will be invoked whenever the vcpu->irq.dev raises its INTR
+ * line
+ */
+static void kvm_vcpu_intr(struct kvm_irqsink *this,
+			  struct kvm_irqdevice *dev,
+			  kvm_irqpin_t pin)
+{
+	struct kvm_vcpu *vcpu = (struct kvm_vcpu*)this->private;
+	unsigned long flags;
+
+	spin_lock_irqsave(&vcpu->irq.lock, flags);
+	__set_bit(pin, &vcpu->irq.pending);
+	spin_unlock_irqrestore(&vcpu->irq.lock, flags);
+}
+
+static void kvm_vcpu_irqsink_init(struct kvm_vcpu *vcpu)
+{
+	struct kvm_irqsink sink = {
+		.set_intr   = kvm_vcpu_intr,
+		.private    = vcpu
+	};
+
+	kvm_irqdevice_register_sink(&vcpu->irq.dev, &sink);
+}
+
+/*
  * Creates some virtual cpus.  Good luck creating more than one.
  */
 static int kvm_vm_ioctl_create_vcpu(struct kvm *kvm, int n)
@@ -2384,6 +2404,12 @@ static int kvm_vm_ioctl_create_vcpu(struct kvm *kvm, int n)
 	if (r < 0)
 		goto out_free_vcpus;
 
+	kvm_irqdevice_init(&vcpu->irq.dev);
+	kvm_vcpu_irqsink_init(vcpu);
+	r = kvm_userint_init(vcpu);
+	if (r < 0)
+		goto out_free_vcpus;
+
 	kvm_arch_ops->vcpu_load(vcpu);
 	r = kvm_mmu_setup(vcpu);
 	if (r >= 0)
diff --git a/drivers/kvm/svm.c b/drivers/kvm/svm.c
index b621403..dd0a149 100644
--- a/drivers/kvm/svm.c
+++ b/drivers/kvm/svm.c
@@ -106,24 +106,6 @@ static unsigned get_addr_size(struct kvm_vcpu *vcpu)
 				(cs_attrib & SVM_SELECTOR_DB_MASK) ? 4 : 2;
 }
 
-static inline u8 pop_irq(struct kvm_vcpu *vcpu)
-{
-	int word_index = __ffs(vcpu->irq_summary);
-	int bit_index = __ffs(vcpu->irq_pending[word_index]);
-	int irq = word_index * BITS_PER_LONG + bit_index;
-
-	clear_bit(bit_index, &vcpu->irq_pending[word_index]);
-	if (!vcpu->irq_pending[word_index])
-		clear_bit(word_index, &vcpu->irq_summary);
-	return irq;
-}
-
-static inline void push_irq(struct kvm_vcpu *vcpu, u8 irq)
-{
-	set_bit(irq, vcpu->irq_pending);
-	set_bit(irq / BITS_PER_LONG, &vcpu->irq_summary);
-}
-
 static inline void clgi(void)
 {
 	asm volatile (SVM_CLGI);
@@ -904,7 +886,12 @@ static int pf_interception(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
 	int r;
 
 	if (is_external_interrupt(exit_int_info))
-		push_irq(vcpu, exit_int_info & SVM_EVTINJ_VEC_MASK);
+		/*
+		 * An exception was taken while we were trying to inject an
+		 * IRQ.  We must defer the injection of the vector until
+		 * the next window.
+		 */
+		kvm_vcpu_irq_push(vcpu, exit_int_info & SVM_EVTINJ_VEC_MASK);
 
 	spin_lock(&vcpu->kvm->lock);
 
@@ -1114,7 +1101,7 @@ static int halt_interception(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
 {
 	vcpu->svm->next_rip = vcpu->svm->vmcb->save.rip + 1;
 	skip_emulated_instruction(vcpu);
-	if (vcpu->irq_summary)
+	if (kvm_vcpu_irq_pending(vcpu))
 		return 1;
 
 	kvm_run->exit_reason = KVM_EXIT_HLT;
@@ -1285,7 +1272,7 @@ static int interrupt_window_interception(struct kvm_vcpu *vcpu,
 	 * possible
 	 */
 	if (kvm_run->request_interrupt_window &&
-	    !vcpu->irq_summary) {
+	    !kvm_vcpu_irq_pending(vcpu)) {
 		++vcpu->stat.irq_window_exits;
 		kvm_run->exit_reason = KVM_EXIT_IRQ_WINDOW_OPEN;
 		return 0;
@@ -1384,60 +1371,135 @@ static void pre_svm_run(struct kvm_vcpu *vcpu)
 }
 
 
-static inline void kvm_do_inject_irq(struct kvm_vcpu *vcpu)
-{
-	struct vmcb_control_area *control;
-
-	control = &vcpu->svm->vmcb->control;
-	control->int_vector = pop_irq(vcpu);
-	control->int_ctl &= ~V_INTR_PRIO_MASK;
-	control->int_ctl |= V_IRQ_MASK |
-		((/*control->int_vector >> 4*/ 0xf) << V_INTR_PRIO_SHIFT);
-}
-
 static void kvm_reput_irq(struct kvm_vcpu *vcpu)
 {
 	struct vmcb_control_area *control = &vcpu->svm->vmcb->control;
 
 	if (control->int_ctl & V_IRQ_MASK) {
 		control->int_ctl &= ~V_IRQ_MASK;
-		push_irq(vcpu, control->int_vector);
+		kvm_vcpu_irq_push(vcpu, control->int_vector);
 	}
 
 	vcpu->interrupt_window_open =
 		!(control->int_state & SVM_INTERRUPT_SHADOW_MASK);
 }
 
-static void do_interrupt_requests(struct kvm_vcpu *vcpu,
-				       struct kvm_run *kvm_run)
+static void do_intr_requests(struct kvm_vcpu *vcpu,
+			    struct kvm_run *kvm_run,
+			    kvm_irqpin_t pin)
 {
 	struct vmcb_control_area *control = &vcpu->svm->vmcb->control;
+	int pending = 0;
 
 	vcpu->interrupt_window_open =
 		(!(control->int_state & SVM_INTERRUPT_SHADOW_MASK) &&
 		 (vcpu->svm->vmcb->save.rflags & X86_EFLAGS_IF));
 
-	if (vcpu->interrupt_window_open && vcpu->irq_summary)
+	if (vcpu->interrupt_window_open) {
 		/*
-		 * If interrupts enabled, and not blocked by sti or mov ss. Good.
+		 * If interrupts enabled, and not blocked by sti or mov ss.
+		 * Good.
 		 */
-		kvm_do_inject_irq(vcpu);
+		struct kvm_irqack_data ack;
+		int r = 0;
+
+		memset(&ack, 0, sizeof(ack));
+
+		switch (pin) {
+		case kvm_irqpin_localint:
+			r = kvm_vcpu_irq_pop(vcpu, &ack);
+			break;
+		case kvm_irqpin_extint:
+			printk(KERN_WARNING "KVM: external-interrupts not " \
+			       "handled yet\n");
+			__clear_bit(pin, &vcpu->irq.pending);
+			break;
+		case kvm_irqpin_nmi:
+			/*
+			 * FIXME: Someday we will handle this using the
+			 * specific SVN NMI features.  For now, just inject
+			 * the NMI as a standard interrupt on vector 2
+			 */
+			ack.flags |= KVM_IRQACKDATA_VECTOR_VALID;
+			ack.vector = 2;
+			__clear_bit(pin, &vcpu->irq.pending);
+			break;
+		default:
+			panic("KVM: unknown interrupt pin raised: %d\n", pin);
+			break;
+		}
+
+		BUG_ON(r < 0);
+
+		if (ack.flags & KVM_IRQACKDATA_VECTOR_VALID) {
+			control = &vcpu->svm->vmcb->control;
+			control->int_vector = ack.vector;
+			control->int_ctl &= ~V_INTR_PRIO_MASK;
+			control->int_ctl |= V_IRQ_MASK |
+				((/*control->int_vector >> 4*/ 0xf) <<
+				 V_INTR_PRIO_SHIFT);
+		}
+	}
 
 	/*
-	 * Interrupts blocked.  Wait for unblock.
+	 * Re-read the pending interrupt state.  If anything is still
+	 * pending we need to cause an exit on the next window
 	 */
-	if (!vcpu->interrupt_window_open &&
-	    (vcpu->irq_summary || kvm_run->request_interrupt_window)) {
+	pending = __kvm_vcpu_irq_all_pending(vcpu);
+
+	if (test_bit(pin, &pending) || kvm_run->request_interrupt_window)
+		/*
+		 * Trigger a VMEXIT on the next IRQ window
+		 */
 		control->intercept |= 1ULL << INTERCEPT_VINTR;
-	} else
-		control->intercept &= ~(1ULL << INTERCEPT_VINTR);
+}
+
+static void clear_pending_controls(struct kvm_vcpu *vcpu)
+{
+	struct vmcb_control_area *control = &vcpu->svm->vmcb->control;
+
+	control->intercept &= ~(1ULL << INTERCEPT_VINTR);
+}
+
+static void do_interrupt_requests(struct kvm_vcpu *vcpu,
+				  struct kvm_run *kvm_run)
+{
+	int pending = __kvm_vcpu_irq_all_pending(vcpu);
+
+	clear_pending_controls(vcpu);
+
+	while (pending) {
+		kvm_irqpin_t pin = __fls(pending);
+
+		switch (pin) {
+		case kvm_irqpin_localint:
+		case kvm_irqpin_extint:
+		case kvm_irqpin_nmi:
+			do_intr_requests(vcpu, kvm_run, pin);
+			break;
+		case kvm_irqpin_smi:
+			/* ignored (for now) */
+			printk(KERN_WARNING "KVM: dropping unhandled SMI\n");
+			__clear_bit(pin, &vcpu->irq.pending);
+			break;
+		case kvm_irqpin_invalid:
+			/* drop */
+			break;
+		default:
+			panic("KVM: unknown interrupt pin raised: %d\n", pin);
+			break;
+		}
+
+		__clear_bit(pin, &pending);
+	}
 }
 
 static void post_kvm_run_save(struct kvm_vcpu *vcpu,
 			      struct kvm_run *kvm_run)
 {
-	kvm_run->ready_for_interrupt_injection = (vcpu->interrupt_window_open &&
-						  vcpu->irq_summary == 0);
+	kvm_run->ready_for_interrupt_injection =
+		(vcpu->interrupt_window_open &&
+		 !kvm_vcpu_irq_pending(vcpu));
 	kvm_run->if_flag = (vcpu->svm->vmcb->save.rflags & X86_EFLAGS_IF) != 0;
 	kvm_run->cr8 = vcpu->cr8;
 	kvm_run->apic_base = vcpu->apic_base;
@@ -1452,7 +1514,7 @@ static void post_kvm_run_save(struct kvm_vcpu *vcpu,
 static int dm_request_for_irq_injection(struct kvm_vcpu *vcpu,
 					  struct kvm_run *kvm_run)
 {
-	return (!vcpu->irq_summary &&
+	return (!kvm_vcpu_irq_pending(vcpu) &&
 		kvm_run->request_interrupt_window &&
 		vcpu->interrupt_window_open &&
 		(vcpu->svm->vmcb->save.rflags & X86_EFLAGS_IF));
@@ -1482,9 +1544,17 @@ static int svm_vcpu_run(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
 	int r;
 
 again:
+	spin_lock(&vcpu->irq.lock);
+
+	/*
+	 * We must inject interrupts (if any) while the irq_lock
+	 * is held
+	 */
 	if (!vcpu->mmio_read_completed)
 		do_interrupt_requests(vcpu, kvm_run);
 
+	spin_unlock(&vcpu->irq.lock);
+
 	clgi();
 
 	pre_svm_run(vcpu);
diff --git a/drivers/kvm/userint.c b/drivers/kvm/userint.c
new file mode 100644
index 0000000..a60707d
--- /dev/null
+++ b/drivers/kvm/userint.c
@@ -0,0 +1,223 @@
+/*
+ * User Interrupts IRQ device
+ *
+ * This acts as an extention of an interrupt controller that exists elsewhere
+ * (typically in userspace/QEMU).  Because this PIC is a pseudo device that
+ * is downstream from a real emulated PIC, the "IRQ-to-vector" mapping has
+ * already occured.  Therefore, this PIC has the following unusal properties:
+ *
+ * 1) It has 256 "pins" which are literal vectors (i.e. no translation)
+ * 2) It only supports "auto-EOI" behavior since it is expected that the
+ *    upstream emulated PIC will handle the real EOIs (if applicable)
+ * 3) It only listens to "asserts" on the pins (deasserts are dropped)
+ *    because its an auto-EOI device anyway.
+ *
+ * Copyright (C) 2007 Novell
+ *
+ * bitarray code based on original vcpu->irq_pending code,
+ *     Copyright (C) 2007 Qumranet
+ *
+ * Authors:
+ *   Gregory Haskins <ghaskins-Et1tbQHTxzrQT0dZR+AlfA@public.gmane.org>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2.  See
+ * the COPYING file in the top-level directory.
+ *
+ */
+
+#include "kvm.h"
+
+/*
+ *----------------------------------------------------------------------
+ * optimized bitarray object - works like bitarrays in bitops, but uses
+ * a summary field to accelerate lookups.  Assumes external locking
+ *---------------------------------------------------------------------
+ */
+
+struct bitarray {
+	unsigned long summary; /* 1 per word in pending */
+	unsigned long pending[NR_IRQ_WORDS];
+};
+
+static inline int bitarray_pending(struct bitarray *this)
+{
+	return this->summary ? 1 : 0;
+}
+
+static inline int bitarray_findhighest(struct bitarray *this)
+{
+	if (!this->summary)
+		return -1;
+	else {
+		int word_index = __fls(this->summary);
+		int bit_index  = __fls(this->pending[word_index]);
+
+		return word_index * BITS_PER_LONG + bit_index;
+	}
+}
+
+static inline void bitarray_set(struct bitarray *this, int nr)
+{
+	__set_bit(nr, &this->pending);
+	__set_bit(nr / BITS_PER_LONG, &this->summary);
+}
+
+static inline void bitarray_clear(struct bitarray *this, int nr)
+{
+	int word = nr / BITS_PER_LONG;
+
+	__clear_bit(nr, &this->pending);
+	if (!this->pending[word])
+		__clear_bit(word, &this->summary);
+}
+
+static inline int bitarray_test(struct bitarray *this, int nr)
+{
+	return test_bit(nr, &this->pending);
+}
+
+static inline int bitarray_test_and_set(struct bitarray *this, int nr, int val)
+{
+	if (bitarray_test(this, nr) != val) {
+		if (val)
+			bitarray_set(this, nr);
+		else
+			bitarray_clear(this, nr);
+		return 1;
+	}
+
+	return 0;
+}
+
+/*
+ *----------------------------------------------------------------------
+ * userint interface - provides the actual kvm_irqdevice implementation
+ *---------------------------------------------------------------------
+ */
+
+struct kvm_user_irqdev {
+	spinlock_t      lock;
+	atomic_t        ref_count;
+	struct bitarray pending;
+};
+
+static int user_irqdev_ack(struct kvm_irqdevice *this, int flags,
+			   struct kvm_irqack_data *data)
+{
+	struct kvm_user_irqdev *s = (struct kvm_user_irqdev*)this->private;
+
+	spin_lock(&s->lock);
+
+	if (!(flags & KVM_IRQACK_FLAG_PEEK)) {
+		int irq = bitarray_findhighest(&s->pending);
+
+		if (irq > -1) {
+			/*
+			 * Automatically clear the interrupt as the EOI
+			 * mechanism (if any) will take place in userspace
+			 */
+			bitarray_clear(&s->pending, irq);
+
+			data->flags |= KVM_IRQACKDATA_VECTOR_VALID;
+		}
+
+		data->vector = irq;
+	}
+
+	if (bitarray_pending(&s->pending))
+		data->flags |= KVM_IRQACKDATA_VECTOR_PENDING;
+
+	spin_unlock(&s->lock);
+
+	return 0;
+}
+
+static int user_irqdev_set_pin(struct kvm_irqdevice *this, int irq, int level)
+{
+	struct kvm_user_irqdev *s = (struct kvm_user_irqdev*)this->private;
+	int forward = 0;
+
+	spin_lock(&s->lock);
+	forward = bitarray_test_and_set(&s->pending, irq, level);
+	spin_unlock(&s->lock);
+
+	/*
+	 * alert the higher layer software we have changes
+	 */
+	if (forward)
+		kvm_irqdevice_set_intr(this, kvm_irqpin_localint);
+
+	return 0;
+}
+
+static void user_irqdev_destructor(struct kvm_irqdevice *this)
+{
+	struct kvm_user_irqdev *s = (struct kvm_user_irqdev*)this->private;
+
+	if (atomic_dec_and_test(&s->ref_count))
+		kfree(s);
+}
+
+int kvm_user_irqdev_init(struct kvm_irqdevice *irqdev)
+{
+	struct kvm_user_irqdev *s;
+
+	s = kzalloc(sizeof(*s), GFP_KERNEL);
+	if (!s)
+		return -ENOMEM;
+
+	spin_lock_init(&s->lock);
+
+	irqdev->ack         = user_irqdev_ack;
+	irqdev->set_pin     = user_irqdev_set_pin;
+	irqdev->destructor  = user_irqdev_destructor;
+
+	irqdev->private = s;
+	atomic_inc(&s->ref_count);
+
+	return 0;
+}
+
+int kvm_user_irqdev_save(struct kvm_irqdevice *this, void *data)
+{
+	struct kvm_user_irqdev *s = (struct kvm_user_irqdev*)this->private;
+
+	spin_lock(&s->lock);
+	memcpy(data, s->pending.pending, sizeof s->pending.pending);
+	spin_unlock(&s->lock);
+
+	return 0;
+}
+
+int kvm_user_irqdev_restore(struct kvm_irqdevice *this, void *data)
+{
+	struct kvm_user_irqdev *s = (struct kvm_user_irqdev*)this->private;
+	int i;
+	int forward = 0;
+
+	spin_lock(&s->lock);
+
+	/*
+	 * walk the interrupt-bitmap and inject an IRQ for each bit found
+	 */
+	for (i = 0; i < 256; ++i) {
+		int val  = test_bit(i, data);
+		forward |= bitarray_test_and_set(&s->pending, i, val);
+	}
+
+	spin_unlock(&s->lock);
+
+	/*
+	 * alert the higher layer software we have changes
+	 */
+	if (forward)
+		kvm_irqdevice_set_intr(this, kvm_irqpin_localint);
+
+	return 0;
+}
+
+int kvm_userint_init(struct kvm_vcpu *vcpu)
+{
+	return kvm_user_irqdev_init(&vcpu->irq.dev);
+}
+
diff --git a/drivers/kvm/vmx.c b/drivers/kvm/vmx.c
index e696d02..e4984eb 100644
--- a/drivers/kvm/vmx.c
+++ b/drivers/kvm/vmx.c
@@ -1415,52 +1415,118 @@ static void inject_rmode_irq(struct kvm_vcpu *vcpu, int irq)
 	vmcs_writel(GUEST_RSP, (vmcs_readl(GUEST_RSP) & ~0xffff) | (sp - 6));
 }
 
-static void kvm_do_inject_irq(struct kvm_vcpu *vcpu)
+static void do_intr_requests(struct kvm_vcpu *vcpu,
+			    struct kvm_run *kvm_run,
+			    kvm_irqpin_t pin)
 {
-	int word_index = __ffs(vcpu->irq_summary);
-	int bit_index = __ffs(vcpu->irq_pending[word_index]);
-	int irq = word_index * BITS_PER_LONG + bit_index;
-
-	clear_bit(bit_index, &vcpu->irq_pending[word_index]);
-	if (!vcpu->irq_pending[word_index])
-		clear_bit(word_index, &vcpu->irq_summary);
-
-	if (vcpu->rmode.active) {
-		inject_rmode_irq(vcpu, irq);
-		return;
-	}
-	vmcs_write32(VM_ENTRY_INTR_INFO_FIELD,
-			irq | INTR_TYPE_EXT_INTR | INTR_INFO_VALID_MASK);
-}
-
-
-static void do_interrupt_requests(struct kvm_vcpu *vcpu,
-				       struct kvm_run *kvm_run)
-{
-	u32 cpu_based_vm_exec_control;
+	int pending = 0;
 
 	vcpu->interrupt_window_open =
 		((vmcs_readl(GUEST_RFLAGS) & X86_EFLAGS_IF) &&
 		 (vmcs_read32(GUEST_INTERRUPTIBILITY_INFO) & 3) == 0);
 
 	if (vcpu->interrupt_window_open &&
-	    vcpu->irq_summary &&
-	    !(vmcs_read32(VM_ENTRY_INTR_INFO_FIELD) & INTR_INFO_VALID_MASK))
+	    !(vmcs_read32(VM_ENTRY_INTR_INFO_FIELD) & INTR_INFO_VALID_MASK)) {
 		/*
-		 * If interrupts enabled, and not blocked by sti or mov ss. Good.
+		 * If interrupts enabled, and not blocked by sti or mov ss.
+		 * Good.
 		 */
-		kvm_do_inject_irq(vcpu);
+		struct kvm_irqack_data ack;
+		int r = 0;
+
+		memset(&ack, 0, sizeof(ack));
+
+		switch (pin) {
+		case kvm_irqpin_localint:
+			r = kvm_vcpu_irq_pop(vcpu, &ack);
+			break;
+		case kvm_irqpin_extint:
+			printk(KERN_WARNING "KVM: external-interrupts not " \
+			       "handled yet\n");
+			__clear_bit(pin, &vcpu->irq.pending);
+			break;
+		case kvm_irqpin_nmi:
+			/*
+			 * FIXME: Someday we will handle this using the
+			 * specific VMX NMI features.  For now, just inject
+			 * the NMI as a standard interrupt on vector 2
+			 */
+			ack.flags |= KVM_IRQACKDATA_VECTOR_VALID;
+			ack.vector = 2;
+			__clear_bit(pin, &vcpu->irq.pending);
+			break;
+		default:
+			panic("KVM: unknown interrupt pin raised: %d\n", pin);
+			break;
+		}
+
+		BUG_ON(r < 0);
 
-	cpu_based_vm_exec_control = vmcs_read32(CPU_BASED_VM_EXEC_CONTROL);
-	if (!vcpu->interrupt_window_open &&
-	    (vcpu->irq_summary || kvm_run->request_interrupt_window))
+		if (ack.flags & KVM_IRQACKDATA_VECTOR_VALID) {
+			if (vcpu->rmode.active)
+				inject_rmode_irq(vcpu, ack.vector);
+			else
+				vmcs_write32(VM_ENTRY_INTR_INFO_FIELD,
+					     ack.vector |
+					     INTR_TYPE_EXT_INTR |
+					     INTR_INFO_VALID_MASK);
+		}
+	}
+
+	/*
+	 * Re-read the pending interrupt state.  If anything is still
+	 * pending we need to cause an exit on the next window
+	 */
+	pending = __kvm_vcpu_irq_all_pending(vcpu);
+
+	if (test_bit(pin, &pending) || kvm_run->request_interrupt_window) {
 		/*
-		 * Interrupts blocked.  Wait for unblock.
+		 * Trigger a VMEXIT on the next IRQ window
 		 */
-		cpu_based_vm_exec_control |= CPU_BASED_VIRTUAL_INTR_PENDING;
-	else
-		cpu_based_vm_exec_control &= ~CPU_BASED_VIRTUAL_INTR_PENDING;
-	vmcs_write32(CPU_BASED_VM_EXEC_CONTROL, cpu_based_vm_exec_control);
+		u32 cbvec = vmcs_read32(CPU_BASED_VM_EXEC_CONTROL);
+		cbvec |= CPU_BASED_VIRTUAL_INTR_PENDING;
+		vmcs_write32(CPU_BASED_VM_EXEC_CONTROL, cbvec);
+	}
+}
+
+static void clear_pending_controls(struct kvm_vcpu *vcpu)
+{
+	u32 cbvec = vmcs_read32(CPU_BASED_VM_EXEC_CONTROL);
+	cbvec &= ~CPU_BASED_VIRTUAL_INTR_PENDING;
+	vmcs_write32(CPU_BASED_VM_EXEC_CONTROL, cbvec);
+}
+
+static void do_interrupt_requests(struct kvm_vcpu *vcpu,
+				  struct kvm_run *kvm_run)
+{
+	int pending = __kvm_vcpu_irq_all_pending(vcpu);
+
+	clear_pending_controls(vcpu);
+
+	while (pending) {
+		kvm_irqpin_t pin = __fls(pending);
+
+		switch (pin) {
+		case kvm_irqpin_localint:
+		case kvm_irqpin_extint:
+		case kvm_irqpin_nmi:
+			do_intr_requests(vcpu, kvm_run, pin);
+			break;
+		case kvm_irqpin_smi:
+			/* ignored (for now) */
+			printk(KERN_WARNING "KVM: dropping unhandled SMI\n");
+			__clear_bit(pin, &vcpu->irq.pending);
+			break;
+		case kvm_irqpin_invalid:
+			/* drop */
+			break;
+		default:
+			panic("KVM: unknown interrupt pin raised: %d\n", pin);
+			break;
+		}
+
+		__clear_bit(pin, &pending);
+	}
 }
 
 static void kvm_guest_debug_pre(struct kvm_vcpu *vcpu)
@@ -1511,9 +1577,13 @@ static int handle_exception(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
 	}
 
 	if (is_external_interrupt(vect_info)) {
+		/*
+		 * An exception was taken while we were trying to inject an
+		 * IRQ.  We must defer the injection of the vector until
+		 * the next window.
+		 */
 		int irq = vect_info & VECTORING_INFO_VECTOR_MASK;
-		set_bit(irq, vcpu->irq_pending);
-		set_bit(irq / BITS_PER_LONG, &vcpu->irq_summary);
+		kvm_vcpu_irq_push(vcpu, irq);
 	}
 
 	if ((intr_info & INTR_INFO_INTR_TYPE_MASK) == 0x200) { /* nmi */
@@ -1829,8 +1899,9 @@ static void post_kvm_run_save(struct kvm_vcpu *vcpu,
 	kvm_run->if_flag = (vmcs_readl(GUEST_RFLAGS) & X86_EFLAGS_IF) != 0;
 	kvm_run->cr8 = vcpu->cr8;
 	kvm_run->apic_base = vcpu->apic_base;
-	kvm_run->ready_for_interrupt_injection = (vcpu->interrupt_window_open &&
-						  vcpu->irq_summary == 0);
+	kvm_run->ready_for_interrupt_injection =
+		(vcpu->interrupt_window_open &&
+		 !kvm_vcpu_irq_pending(vcpu));
 }
 
 static int handle_interrupt_window(struct kvm_vcpu *vcpu,
@@ -1841,7 +1912,7 @@ static int handle_interrupt_window(struct kvm_vcpu *vcpu,
 	 * possible
 	 */
 	if (kvm_run->request_interrupt_window &&
-	    !vcpu->irq_summary) {
+	    !kvm_vcpu_irq_pending(vcpu)) {
 		kvm_run->exit_reason = KVM_EXIT_IRQ_WINDOW_OPEN;
 		++vcpu->stat.irq_window_exits;
 		return 0;
@@ -1852,7 +1923,7 @@ static int handle_interrupt_window(struct kvm_vcpu *vcpu,
 static int handle_halt(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
 {
 	skip_emulated_instruction(vcpu);
-	if (vcpu->irq_summary)
+	if (kvm_vcpu_irq_pending(vcpu))
 		return 1;
 
 	kvm_run->exit_reason = KVM_EXIT_HLT;
@@ -1922,7 +1993,7 @@ static int kvm_handle_exit(struct kvm_run *kvm_run, struct kvm_vcpu *vcpu)
 static int dm_request_for_irq_injection(struct kvm_vcpu *vcpu,
 					  struct kvm_run *kvm_run)
 {
-	return (!vcpu->irq_summary &&
+	return (!kvm_vcpu_irq_pending(vcpu) &&
 		kvm_run->request_interrupt_window &&
 		vcpu->interrupt_window_open &&
 		(vmcs_readl(GUEST_RFLAGS) & X86_EFLAGS_IF));
@@ -1938,9 +2009,17 @@ preempted:
 		kvm_guest_debug_pre(vcpu);
 
 again:
+	spin_lock(&vcpu->irq.lock);
+
+	/*
+	 * We must inject interrupts (if any) while the irq.lock
+	 * is held
+	 */
 	if (!vcpu->mmio_read_completed)
 		do_interrupt_requests(vcpu, kvm_run);
 
+	spin_unlock(&vcpu->irq.lock);
+
 	vmx_save_host_state(vcpu);
 	kvm_load_guest_fpu(vcpu);
 


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[PATCH 4/9] KVM: Adds ability to preempt an executing VCPU

[Gregory Haskins]

The VCPU executes synchronously w.r.t. userspace today, and therefore
interrupt injection is pretty straight forward.  However, we will soon need
to be able to inject interrupts asynchronous to the execution of the VCPU
due to the introduction of SMP, paravirtualized drivers, and asynchronous
hypercalls.  This patch adds support to the interrupt mechanism to force
a VCPU to VMEXIT when a new interrupt is pending.

Signed-off-by: Gregory Haskins <ghaskins-Et1tbQHTxzrQT0dZR+AlfA@public.gmane.org>
---

 drivers/kvm/kvm.h      |    2 ++
 drivers/kvm/kvm_main.c |   64 +++++++++++++++++++++++++++++++++++++++++++++---
 drivers/kvm/svm.c      |   52 +++++++++++++++++++++++++++++++++++++--
 drivers/kvm/vmx.c      |   38 +++++++++++++++++++++++++++++
 4 files changed, 149 insertions(+), 7 deletions(-)

diff --git a/drivers/kvm/kvm.h b/drivers/kvm/kvm.h
index 41e4eaa..d5783dc 100644
--- a/drivers/kvm/kvm.h
+++ b/drivers/kvm/kvm.h
@@ -331,6 +331,7 @@ struct kvm_vcpu_irq {
 	struct kvm_irqdevice dev;
 	int                  pending;
 	int                  deferred;
+	int                  guest_cpu;
 };
 
 struct kvm_vcpu {
@@ -346,6 +347,7 @@ struct kvm_vcpu {
 	struct kvm_run *run;
 	int interrupt_window_open;
 	struct kvm_vcpu_irq irq;
+	pid_t owner;
 	unsigned long regs[NR_VCPU_REGS]; /* for rsp: vcpu_load_rsp_rip() */
 	unsigned long rip;      /* needs vcpu_load_rsp_rip() */
 
diff --git a/drivers/kvm/kvm_main.c b/drivers/kvm/kvm_main.c
index a2e1e50..0c6a62a 100644
--- a/drivers/kvm/kvm_main.c
+++ b/drivers/kvm/kvm_main.c
@@ -1891,6 +1891,9 @@ static int kvm_vcpu_ioctl_run(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
 		kvm_arch_ops->decache_regs(vcpu);
 	}
 
+	vcpu->owner = current->pid;
+	smp_wmb();
+
 	r = kvm_arch_ops->run(vcpu, kvm_run);
 
 out:
@@ -2332,6 +2335,20 @@ out1:
 }
 
 /*
+ * This function is invoked whenever we want to interrupt a vcpu that is
+ * currently executing in guest-mode.  It currently is a no-op because
+ * the simple delivery of the IPI to execute this function accomplishes our
+ * goal: To cause a VMEXIT.  We pass the vcpu (which contains the
+ * vcpu->irq.task, etc) for future use
+ */
+static void kvm_vcpu_guest_intr(void *info)
+{
+#ifdef NOT_YET
+	struct kvm_vcpu *vcpu = (struct kvm_vcpu*)info;
+#endif
+}
+
+/*
  * This function will be invoked whenever the vcpu->irq.dev raises its INTR
  * line
  */
@@ -2340,11 +2357,50 @@ static void kvm_vcpu_intr(struct kvm_irqsink *this,
 			  kvm_irqpin_t pin)
 {
 	struct kvm_vcpu *vcpu = (struct kvm_vcpu*)this->private;
-	unsigned long flags;
+	int direct_ipi = -1;
+
+	spin_lock_irq(&vcpu->irq.lock);
+
+	if (!test_bit(pin, &vcpu->irq.pending)) {
+		/*
+		 * Record the change..
+		 */
+		__set_bit(pin, &vcpu->irq.pending);
 
-	spin_lock_irqsave(&vcpu->irq.lock, flags);
-	__set_bit(pin, &vcpu->irq.pending);
-	spin_unlock_irqrestore(&vcpu->irq.lock, flags);
+		/*
+		 * then wake up the vcpu (if necessary)
+		 */
+		if (vcpu->owner != current->pid) {
+			if (vcpu->irq.guest_cpu != -1) {
+				/*
+				 * If we are in guest mode, we can optimize
+				 * the interrupt by invoking a host-IPI to the
+				 * CPU which is running the guest.
+				 */
+				direct_ipi = vcpu->irq.guest_cpu;
+				BUG_ON(direct_ipi == smp_processor_id());
+			}
+		}
+	}
+
+	spin_unlock_irq(&vcpu->irq.lock);
+
+	/*
+	 * we can safely send the IPI outside of the lock-scope because the
+	 * irq.pending has already been updated.  This code assumes that
+	 * userspace will not sleep on anything other than HLT instructions.
+	 * HLT is covered in a race-free way because irq.pending was updated
+	 * in the critical section, and handle_halt() which check if any
+	 * interrupts are pending before returning to userspace.
+	 *
+	 * If it turns out that userspace can sleep on conditions other than
+	 * HLT, this code will need to be enhanced to allow the irq.pending
+	 * flags to be exported to userspace
+	 */
+	if (direct_ipi != -1)
+		smp_call_function_single(direct_ipi,
+					 kvm_vcpu_guest_intr,
+					 vcpu, 0, 0);
 }
 
 static void kvm_vcpu_irqsink_init(struct kvm_vcpu *vcpu)
diff --git a/drivers/kvm/svm.c b/drivers/kvm/svm.c
index dd0a149..6c6228d 100644
--- a/drivers/kvm/svm.c
+++ b/drivers/kvm/svm.c
@@ -1544,9 +1544,43 @@ static int svm_vcpu_run(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
 	int r;
 
 again:
+	/*
+	 * We disable interrupts until the next VMEXIT to eliminate a race
+	 * condition for delivery of virtual interrutps.  Note that this is
+	 * probably not as bad as it sounds, as interrupts will still invoke
+	 * a VMEXIT once transitioned to GUEST mode (and thus exit this lock
+	 * scope) even if they are disabled.
+	 */
+	local_irq_disable();
+
 	spin_lock(&vcpu->irq.lock);
 
 	/*
+	 * If there are any signals pending (virtual interrupt related or
+	 * otherwise), don't even bother trying to enter guest mode...
+	 */
+	if (signal_pending(current)) {
+		kvm_run->exit_reason = KVM_EXIT_INTR;
+		spin_unlock(&vcpu->irq.lock);
+		local_irq_enable();
+		r = -EINTR;
+		/*
+		 * FIXME: We probably want to move this whole lock-block below
+		 * the host->guest state loading so we don't restore when
+		 * the system was never saved to begin with
+		 */
+		goto out;
+	}
+
+	/*
+	 * There are optimizations we can make when signaling interrupts
+	 * if we know the VCPU is in GUEST mode, so record the guest's
+	 * CPU to both serve as an indicator of vcpu state and a target
+	 * for our interrupts
+	 */
+	vcpu->irq.guest_cpu = task_cpu(current);
+
+	/*
 	 * We must inject interrupts (if any) while the irq_lock
 	 * is held
 	 */
@@ -1688,6 +1722,15 @@ again:
 #endif
 		: "cc", "memory" );
 
+	/*
+	 * Signal that we have transitioned back to host mode
+	 */
+	spin_lock(&vcpu->irq.lock);
+	vcpu->irq.guest_cpu = -1;
+	spin_unlock(&vcpu->irq.lock);
+
+	local_irq_enable();
+
 	if (vcpu->fpu_active) {
 		fx_save(vcpu->guest_fx_image);
 		fx_restore(vcpu->host_fx_image);
@@ -1734,20 +1777,23 @@ again:
 	if (r > 0) {
 		if (signal_pending(current)) {
 			++vcpu->stat.signal_exits;
-			post_kvm_run_save(vcpu, kvm_run);
 			kvm_run->exit_reason = KVM_EXIT_INTR;
-			return -EINTR;
+			r = -EINTR;
+			goto out;
 		}
 
 		if (dm_request_for_irq_injection(vcpu, kvm_run)) {
 			++vcpu->stat.request_irq_exits;
 			post_kvm_run_save(vcpu, kvm_run);
 			kvm_run->exit_reason = KVM_EXIT_INTR;
-			return -EINTR;
+			r = -EINTR;
+			goto out;
 		}
 		kvm_resched(vcpu);
 		goto again;
 	}
+
+ out:
 	post_kvm_run_save(vcpu, kvm_run);
 	return r;
 }
diff --git a/drivers/kvm/vmx.c b/drivers/kvm/vmx.c
index e4984eb..543c27e 100644
--- a/drivers/kvm/vmx.c
+++ b/drivers/kvm/vmx.c
@@ -2009,9 +2009,38 @@ preempted:
 		kvm_guest_debug_pre(vcpu);
 
 again:
+	/*
+	 * We disable interrupts until the next VMEXIT to eliminate a race
+	 * condition for delivery of virtual interrutps.  Note that this is
+	 * probably not as bad as it sounds, as interrupts will still invoke
+	 * a VMEXIT once transitioned to GUEST mode (and thus exit this lock
+	 * scope) even if they are disabled.
+	 */
+	local_irq_disable();
+
 	spin_lock(&vcpu->irq.lock);
 
 	/*
+	 * If there are any signals pending (virtual interrupt related or
+	 * otherwise), don't even bother trying to enter guest mode...
+	 */
+	if (signal_pending(current)) {
+		kvm_run->exit_reason = KVM_EXIT_INTR;
+		spin_unlock(&vcpu->irq.lock);
+		local_irq_enable();
+		r = -EINTR;
+		goto out;
+	}
+
+	/*
+	 * There are optimizations we can make when signaling interrupts
+	 * if we know the VCPU is in GUEST mode, so record the guest's
+	 * CPU to both serve as an indicator of vcpu state and a target
+	 * for our interrupts
+	 */
+	vcpu->irq.guest_cpu = task_cpu(current);
+
+	/*
 	 * We must inject interrupts (if any) while the irq.lock
 	 * is held
 	 */
@@ -2147,6 +2176,15 @@ again:
 		[cr2]"i"(offsetof(struct kvm_vcpu, cr2))
 	      : "cc", "memory" );
 
+	/*
+	 * Signal that we have transitioned back to host mode
+	 */
+	spin_lock(&vcpu->irq.lock);
+	vcpu->irq.guest_cpu = -1;
+	spin_unlock(&vcpu->irq.lock);
+
+	local_irq_enable();
+
 	++vcpu->stat.exits;
 
 	vcpu->interrupt_window_open = (vmcs_read32(GUEST_INTERRUPTIBILITY_INFO) & 3) == 0;


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[PATCH 5/9] KVM: Adds ability to signal userspace using a file-descriptor

[Gregory Haskins]

Signed-off-by: Gregory Haskins <ghaskins-Et1tbQHTxzrQT0dZR+AlfA@public.gmane.org>
---

 drivers/kvm/kvm.h      |    1 +
 drivers/kvm/kvm_main.c |   55 +++++++++++++++++++++++++++++++++++++++++++-----
 include/linux/kvm.h    |    1 +
 3 files changed, 51 insertions(+), 6 deletions(-)

diff --git a/drivers/kvm/kvm.h b/drivers/kvm/kvm.h
index d5783dc..e1ba066 100644
--- a/drivers/kvm/kvm.h
+++ b/drivers/kvm/kvm.h
@@ -332,6 +332,7 @@ struct kvm_vcpu_irq {
 	int                  pending;
 	int                  deferred;
 	int                  guest_cpu;
+	int                  eventfd;
 };
 
 struct kvm_vcpu {
diff --git a/drivers/kvm/kvm_main.c b/drivers/kvm/kvm_main.c
index 0c6a62a..7109b66 100644
--- a/drivers/kvm/kvm_main.c
+++ b/drivers/kvm/kvm_main.c
@@ -40,6 +40,7 @@
 #include <linux/file.h>
 #include <linux/fs.h>
 #include <linux/mount.h>
+#include <linux/eventfd.h>
 
 #include "x86_emulate.h"
 #include "segment_descriptor.h"
@@ -326,6 +327,7 @@ static struct kvm *kvm_create_vm(void)
 		memset(&vcpu->irq, 0, sizeof(vcpu->irq));
 		spin_lock_init(&vcpu->irq.lock);
 		vcpu->irq.deferred = -1;
+		vcpu->irq.eventfd   = -1;
 
 		vcpu->cpu = -1;
 		vcpu->kvm = kvm;
@@ -2358,6 +2360,7 @@ static void kvm_vcpu_intr(struct kvm_irqsink *this,
 {
 	struct kvm_vcpu *vcpu = (struct kvm_vcpu*)this->private;
 	int direct_ipi = -1;
+	int eventfd = -1;
 
 	spin_lock_irq(&vcpu->irq.lock);
 
@@ -2379,7 +2382,14 @@ static void kvm_vcpu_intr(struct kvm_irqsink *this,
 				 */
 				direct_ipi = vcpu->irq.guest_cpu;
 				BUG_ON(direct_ipi == smp_processor_id());
-			}
+			} else
+				/*
+				 * otherwise, we must assume that we could be
+				 * blocked anywhere, including userspace. Send
+				 * a signal to give everyone a chance to get
+				 * notification
+				 */
+				eventfd = vcpu->irq.eventfd;
 		}
 	}
 
@@ -2401,6 +2411,12 @@ static void kvm_vcpu_intr(struct kvm_irqsink *this,
 		smp_call_function_single(direct_ipi,
 					 kvm_vcpu_guest_intr,
 					 vcpu, 0, 0);
+
+	if (eventfd != -1) {
+		struct file *filp = eventfd_fget(eventfd);
+		if (!IS_ERR(filp))
+			eventfd_signal(filp, 1);
+	}
 }
 
 static void kvm_vcpu_irqsink_init(struct kvm_vcpu *vcpu)
@@ -2584,6 +2600,17 @@ static int kvm_vcpu_ioctl_set_fpu(struct kvm_vcpu *vcpu, struct kvm_fpu *fpu)
 	return 0;
 }
 
+static int kvm_vcpu_ioctl_set_eventfd(struct kvm_vcpu *vcpu, int fd)
+{
+	if (IS_ERR(eventfd_fget(fd)))
+		return -EINVAL;
+
+	vcpu->irq.eventfd = fd;
+	smp_wmb();
+
+	return 0;
+}
+
 static long kvm_vcpu_ioctl(struct file *filp,
 			   unsigned int ioctl, unsigned long arg)
 {
@@ -2753,6 +2780,15 @@ static long kvm_vcpu_ioctl(struct file *filp,
 		r = 0;
 		break;
 	}
+	case KVM_SET_EVENTFD: {
+		int eventfd = (long)argp;
+
+		r = kvm_vcpu_ioctl_set_eventfd(vcpu, eventfd);
+		if (r)
+			goto out;
+		r = 0;
+		break;
+	}
 	default:
 		;
 	}
@@ -2937,12 +2973,19 @@ static long kvm_dev_ioctl(struct file *filp,
 		r = 0;
 		break;
 	}
-	case KVM_CHECK_EXTENSION:
-		/*
-		 * No extensions defined at present.
-		 */
-		r = 0;
+	case KVM_CHECK_EXTENSION: {
+		int ext = (long)argp;
+
+		switch (ext) {
+		case KVM_SET_EVENTFD:
+			r = 1;
+			break;
+		default:
+			r = 0;
+			break;
+		}
 		break;
+	}
 	case KVM_GET_VCPU_MMAP_SIZE:
 		r = -EINVAL;
 		if (arg)
diff --git a/include/linux/kvm.h b/include/linux/kvm.h
index e6edca8..f13ec8c 100644
--- a/include/linux/kvm.h
+++ b/include/linux/kvm.h
@@ -300,5 +300,6 @@ struct kvm_signal_mask {
 #define KVM_SET_SIGNAL_MASK       _IOW(KVMIO,  0x8b, struct kvm_signal_mask)
 #define KVM_GET_FPU               _IOR(KVMIO,  0x8c, struct kvm_fpu)
 #define KVM_SET_FPU               _IOW(KVMIO,  0x8d, struct kvm_fpu)
+#define KVM_SET_EVENTFD           _IO(KVMIO,   0x8e)
 
 #endif


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Re: [PATCH 5/9] KVM: Adds ability to signal userspace using a file-descriptor

[Anthony Liguori]

This patch series depends on eventfd which means that KVM now requires 
2.6.22-rc1.

While KVM will inevitably start requiring newer kernel versions, do we 
really need to do it right now?  Perhaps we could add dummy eventfd_* 
functions to the module compat header?  Then at least older kernels will 
continue to work with in-kernel APIC disabled.

Regards,

Anthony Liguori

Gregory Haskins wrote:
> Signed-off-by: Gregory Haskins <ghaskins-Et1tbQHTxzrQT0dZR+AlfA@public.gmane.org>
> ---
>
>  drivers/kvm/kvm.h      |    1 +
>  drivers/kvm/kvm_main.c |   55 +++++++++++++++++++++++++++++++++++++++++++-----
>  include/linux/kvm.h    |    1 +
>  3 files changed, 51 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/kvm/kvm.h b/drivers/kvm/kvm.h
> index d5783dc..e1ba066 100644
> --- a/drivers/kvm/kvm.h
> +++ b/drivers/kvm/kvm.h
> @@ -332,6 +332,7 @@ struct kvm_vcpu_irq {
>  	int                  pending;
>  	int                  deferred;
>  	int                  guest_cpu;
> +	int                  eventfd;
>  };
>  
>  struct kvm_vcpu {
> diff --git a/drivers/kvm/kvm_main.c b/drivers/kvm/kvm_main.c
> index 0c6a62a..7109b66 100644
> --- a/drivers/kvm/kvm_main.c
> +++ b/drivers/kvm/kvm_main.c
> @@ -40,6 +40,7 @@
>  #include <linux/file.h>
>  #include <linux/fs.h>
>  #include <linux/mount.h>
> +#include <linux/eventfd.h>
>  
>  #include "x86_emulate.h"
>  #include "segment_descriptor.h"
> @@ -326,6 +327,7 @@ static struct kvm *kvm_create_vm(void)
>  		memset(&vcpu->irq, 0, sizeof(vcpu->irq));
>  		spin_lock_init(&vcpu->irq.lock);
>  		vcpu->irq.deferred = -1;
> +		vcpu->irq.eventfd   = -1;
>  
>  		vcpu->cpu = -1;
>  		vcpu->kvm = kvm;
> @@ -2358,6 +2360,7 @@ static void kvm_vcpu_intr(struct kvm_irqsink *this,
>  {
>  	struct kvm_vcpu *vcpu = (struct kvm_vcpu*)this->private;
>  	int direct_ipi = -1;
> +	int eventfd = -1;
>  
>  	spin_lock_irq(&vcpu->irq.lock);
>  
> @@ -2379,7 +2382,14 @@ static void kvm_vcpu_intr(struct kvm_irqsink *this,
>  				 */
>  				direct_ipi = vcpu->irq.guest_cpu;
>  				BUG_ON(direct_ipi == smp_processor_id());
> -			}
> +			} else
> +				/*
> +				 * otherwise, we must assume that we could be
> +				 * blocked anywhere, including userspace. Send
> +				 * a signal to give everyone a chance to get
> +				 * notification
> +				 */
> +				eventfd = vcpu->irq.eventfd;
>  		}
>  	}
>  
> @@ -2401,6 +2411,12 @@ static void kvm_vcpu_intr(struct kvm_irqsink *this,
>  		smp_call_function_single(direct_ipi,
>  					 kvm_vcpu_guest_intr,
>  					 vcpu, 0, 0);
> +
> +	if (eventfd != -1) {
> +		struct file *filp = eventfd_fget(eventfd);
> +		if (!IS_ERR(filp))
> +			eventfd_signal(filp, 1);
> +	}
>  }
>  
>  static void kvm_vcpu_irqsink_init(struct kvm_vcpu *vcpu)
> @@ -2584,6 +2600,17 @@ static int kvm_vcpu_ioctl_set_fpu(struct kvm_vcpu *vcpu, struct kvm_fpu *fpu)
>  	return 0;
>  }
>  
> +static int kvm_vcpu_ioctl_set_eventfd(struct kvm_vcpu *vcpu, int fd)
> +{
> +	if (IS_ERR(eventfd_fget(fd)))
> +		return -EINVAL;
> +
> +	vcpu->irq.eventfd = fd;
> +	smp_wmb();
> +
> +	return 0;
> +}
> +
>  static long kvm_vcpu_ioctl(struct file *filp,
>  			   unsigned int ioctl, unsigned long arg)
>  {
> @@ -2753,6 +2780,15 @@ static long kvm_vcpu_ioctl(struct file *filp,
>  		r = 0;
>  		break;
>  	}
> +	case KVM_SET_EVENTFD: {
> +		int eventfd = (long)argp;
> +
> +		r = kvm_vcpu_ioctl_set_eventfd(vcpu, eventfd);
> +		if (r)
> +			goto out;
> +		r = 0;
> +		break;
> +	}
>  	default:
>  		;
>  	}
> @@ -2937,12 +2973,19 @@ static long kvm_dev_ioctl(struct file *filp,
>  		r = 0;
>  		break;
>  	}
> -	case KVM_CHECK_EXTENSION:
> -		/*
> -		 * No extensions defined at present.
> -		 */
> -		r = 0;
> +	case KVM_CHECK_EXTENSION: {
> +		int ext = (long)argp;
> +
> +		switch (ext) {
> +		case KVM_SET_EVENTFD:
> +			r = 1;
> +			break;
> +		default:
> +			r = 0;
> +			break;
> +		}
>  		break;
> +	}
>  	case KVM_GET_VCPU_MMAP_SIZE:
>  		r = -EINVAL;
>  		if (arg)
> diff --git a/include/linux/kvm.h b/include/linux/kvm.h
> index e6edca8..f13ec8c 100644
> --- a/include/linux/kvm.h
> +++ b/include/linux/kvm.h
> @@ -300,5 +300,6 @@ struct kvm_signal_mask {
>  #define KVM_SET_SIGNAL_MASK       _IOW(KVMIO,  0x8b, struct kvm_signal_mask)
>  #define KVM_GET_FPU               _IOR(KVMIO,  0x8c, struct kvm_fpu)
>  #define KVM_SET_FPU               _IOW(KVMIO,  0x8d, struct kvm_fpu)
> +#define KVM_SET_EVENTFD           _IO(KVMIO,   0x8e)
>  
>  #endif
>
>
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Re: [PATCH 5/9] KVM: Adds ability to signal userspace using a file-descriptor

[Gregory Haskins]

>>> On Tue, May 15, 2007 at 12:39 PM, in message <4649E22F.3090308-r/Jw6+rmf7HQT0dZR+AlfA@public.gmane.org>,
Anthony Liguori <aliguori-r/Jw6+rmf7HQT0dZR+AlfA@public.gmane.org> wrote: 
> This patch series depends on eventfd which means that KVM now requires 
> 2.6.22- rc1.

This is understood.

> 
> While KVM will inevitably start requiring newer kernel versions, do we 
> really need to do it right now?  Perhaps we could add dummy eventfd_* 
> functions to the module compat header?  Then at least older kernels will 
> continue to work with in- kernel APIC disabled.
>

The plan as Avi and I agreed to (IIUC) is to support eventfd via the extern-compat header.  The same could be said for HRT.  I don't thing either one will be particularly pleasant to support in this fashion, but this is how he wants to do it.  (Recall that I had abstracted the HRT in earlier versions which he requested to be removed, so I didnt bother with the eventfd interface).  I agree that it will keep the kvm core code cleaner instead of having all these custom abstractions, so I see his point there.  I'm just not looking forward to the compat work ;)

That being said: Perhaps you just came up with a good compromise.  The code is already structured to support both the old way and the new way.  We could have the in-kernel modes disabled at compile time on older kernels.  Thats probably a much better solution then trying to get HRT and eventfd emulated on, say, 2.6.9 ;)

The implication here is that I don't plan on supporting new features via the old-way.  For instance, SMP features would only work with in-kernel emulation.  If we go down this route, it automatically means that older kernels will not have any other related advanced features, not just the performance/features currently offered.  Perhaps this is acceptable also?  I'm not sure.

Regards,
-Greg 



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Re: [PATCH 5/9] KVM: Adds ability to signal userspace using a file-descriptor

[Anthony Liguori]

Gregory Haskins wrote:
>> While KVM will inevitably start requiring newer kernel versions, do we 
>> really need to do it right now?  Perhaps we could add dummy eventfd_* 
>> functions to the module compat header?  Then at least older kernels will 
>> continue to work with in- kernel APIC disabled.
>>
>>     
>
> The plan as Avi and I agreed to (IIUC) is to support eventfd via the extern-compat header.  The same could be said for HRT.  I don't thing either one will be particularly pleasant to support in this fashion, but this is how he wants to do it.  (Recall that I had abstracted the HRT in earlier versions which he requested to be removed, so I didnt bother with the eventfd interface).  I agree that it will keep the kvm core code cleaner instead of having all these custom abstractions, so I see his point there.  I'm just not looking forward to the compat work ;)
>
> That being said: Perhaps you just came up with a good compromise.  The code is already structured to support both the old way and the new way.  We could have the in-kernel modes disabled at compile time on older kernels.  Thats probably a much better solution then trying to get HRT and eventfd emulated on, say, 2.6.9 ;)
>
> The implication here is that I don't plan on supporting new features via the old-way.  For instance, SMP features would only work with in-kernel emulation.  If we go down this route, it automatically means that older kernels will not have any other related advanced features, not just the performance/features currently offered.  Perhaps this is acceptable also?  I'm not sure.
>   

I don't know.  I'm less concerned about long term implications than I am 
with short term ones.  My primary concern was having new versions of KVM 
stop working on older kernels.  If SMP requires in-kernel APIC, then 
provided that UP kernels still work, if someone is sufficiently 
motivated to get SMP working on older kernels, they can implement the 
eventfd emulation.

Regards,

Anthony Liguori

> Regards,
> -Greg 
>
>
>
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Re: [PATCH 5/9] KVM: Adds ability to signal userspace using a file-descriptor

[Avi Kivity]

Anthony Liguori wrote:
> Gregory Haskins wrote:
>   
>>> While KVM will inevitably start requiring newer kernel versions, do we 
>>> really need to do it right now?  Perhaps we could add dummy eventfd_* 
>>> functions to the module compat header?  Then at least older kernels will 
>>> continue to work with in- kernel APIC disabled.
>>>
>>>     
>>>       
>> The plan as Avi and I agreed to (IIUC) is to support eventfd via the extern-compat header.  The same could be said for HRT.  I don't thing either one will be particularly pleasant to support in this fashion, but this is how he wants to do it.  (Recall that I had abstracted the HRT in earlier versions which he requested to be removed, so I didnt bother with the eventfd interface).  I agree that it will keep the kvm core code cleaner instead of having all these custom abstractions, so I see his point there.  I'm just not looking forward to the compat work ;)
>>
>> That being said: Perhaps you just came up with a good compromise.  The code is already structured to support both the old way and the new way.  We could have the in-kernel modes disabled at compile time on older kernels.  Thats probably a much better solution then trying to get HRT and eventfd emulated on, say, 2.6.9 ;)
>>
>> The implication here is that I don't plan on supporting new features via the old-way.  For instance, SMP features would only work with in-kernel emulation.  If we go down this route, it automatically means that older kernels will not have any other related advanced features, not just the performance/features currently offered.  Perhaps this is acceptable also?  I'm not sure.
>>   
>>     
>
> I don't know.  I'm less concerned about long term implications than I am 
> with short term ones.  My primary concern was having new versions of KVM 
> stop working on older kernels.  If SMP requires in-kernel APIC, then 
> provided that UP kernels still work, if someone is sufficiently 
> motivated to get SMP working on older kernels, they can implement the 
> eventfd emulation.
>
>   

I'm not worried about eventfd -- we can just ship a 
conditionally-compiled copy of the code with the external module (we 
also need a non-syscall interface, as modules can't provide syscalls, 
but that's easily workaroundable).  hrtimers is more difficult, but 
there's really no choice -- we can't #ifdef the core code for that.

I really would like to see smp working without kernel apic, as pure qemu 
supports it.  It would of course require newer modules.

-- 
error compiling committee.c: too many arguments to function


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[PATCH 6/9] KVM: Add support for in-kernel LAPIC model

[Gregory Haskins]

Signed-off-by: Gregory Haskins <ghaskins-Et1tbQHTxzrQT0dZR+AlfA@public.gmane.org>
---

 drivers/kvm/Makefile   |    2 
 drivers/kvm/kernint.c  |  149 +++++
 drivers/kvm/kvm.h      |   35 +
 drivers/kvm/kvm_main.c |  182 ++++++
 drivers/kvm/lapic.c    | 1421 ++++++++++++++++++++++++++++++++++++++++++++++++
 drivers/kvm/svm.c      |   13 
 drivers/kvm/userint.c  |    8 
 drivers/kvm/vmx.c      |   16 -
 include/linux/kvm.h    |   15 +
 9 files changed, 1801 insertions(+), 40 deletions(-)

diff --git a/drivers/kvm/Makefile b/drivers/kvm/Makefile
index 540afbc..1aad737 100644
--- a/drivers/kvm/Makefile
+++ b/drivers/kvm/Makefile
@@ -2,7 +2,7 @@
 # Makefile for Kernel-based Virtual Machine module
 #
 
-kvm-objs := kvm_main.o mmu.o x86_emulate.o userint.o
+kvm-objs := kvm_main.o mmu.o x86_emulate.o userint.o lapic.o kernint.o
 obj-$(CONFIG_KVM) += kvm.o
 kvm-intel-objs = vmx.o
 obj-$(CONFIG_KVM_INTEL) += kvm-intel.o
diff --git a/drivers/kvm/kernint.c b/drivers/kvm/kernint.c
new file mode 100644
index 0000000..b5cbcae
--- /dev/null
+++ b/drivers/kvm/kernint.c
@@ -0,0 +1,149 @@
+/*
+ * Kernel Interrupt IRQ device
+ *
+ * Provides a model for connecting in-kernel interrupt resources to a VCPU.
+ *
+ * A typical modern x86 processor has the concept of an internal Local-APIC
+ * and some external signal pins.  The way in which interrupts are injected is
+ * dependent on whether software enables the LAPIC or not.  When enabled,
+ * interrupts are acknowledged through the LAPIC.  Otherwise they are through
+ * an externally connected PIC (typically an i8259 on the BSP)
+ *
+ * Copyright (C) 2007 Novell
+ *
+ * Authors:
+ *   Gregory Haskins <ghaskins-Et1tbQHTxzrQT0dZR+AlfA@public.gmane.org>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2.  See
+ * the COPYING file in the top-level directory.
+ *
+ */
+
+#include "kvm.h"
+
+struct kvm_kernint {
+	struct kvm_vcpu              *vcpu;
+	struct kvm_irqdevice         *self_irq;
+	struct kvm_irqdevice         *ext_irq;
+	struct kvm_irqdevice          apic_irq;
+
+};
+
+static struct kvm_irqdevice *get_irq_dev(struct kvm_kernint *s)
+{
+	struct kvm_irqdevice *dev;
+
+	if (kvm_lapic_enabled(s->vcpu))
+		dev = &s->apic_irq;
+	else
+		dev = s->ext_irq;
+
+	if (!dev)
+		kvm_crash_guest(s->vcpu->kvm);
+
+	return dev;
+}
+
+static int kernint_irqdev_ack(struct kvm_irqdevice *this, int flags,
+			      struct kvm_irqack_data *data)
+{
+	struct kvm_kernint *s = (struct kvm_kernint*)this->private;
+
+	return kvm_irqdevice_ack(get_irq_dev(s), flags, data);
+}
+
+static int kernint_irqdev_set_pin(struct kvm_irqdevice *this,
+				  int irq, int level)
+{
+	/* no-op */
+	return 0;
+}
+
+static void kernint_irqdev_destructor(struct kvm_irqdevice *this)
+{
+	struct kvm_kernint *s = (struct kvm_kernint*)this->private;
+
+	kvm_irqdevice_destructor(&s->apic_irq);
+	kvm_lapic_destroy(s->vcpu);
+	kfree(s);
+}
+
+static void kvm_apic_intr(struct kvm_irqsink *this,
+			  struct kvm_irqdevice *dev,
+			  kvm_irqpin_t pin)
+{
+	struct kvm_kernint *s = (struct kvm_kernint*)this->private;
+
+	/*
+	 * If the LAPIC sent us an interrupt it *must* be enabled,
+	 * just forward it on to the CPU
+	 */
+	kvm_irqdevice_set_intr(s->self_irq, pin);
+}
+
+static void kvm_ext_intr(struct kvm_irqsink *this,
+			 struct kvm_irqdevice *dev,
+			 kvm_irqpin_t pin)
+{
+	struct kvm_kernint *s = (struct kvm_kernint*)this->private;
+
+	/*
+	 * If the EXTINT device sent us an interrupt, forward it to the LINT0
+	 * pin of the LAPIC
+	 */
+	if (pin != kvm_irqpin_localint)
+		return;
+
+	/*
+	 * "irq 0" = LINT0, 1 = LINT1
+	 */
+	kvm_irqdevice_set_pin(&s->apic_irq, 0, 1);
+}
+
+int kvm_kernint_init(struct kvm_vcpu *vcpu)
+{
+	struct kvm_irqdevice *irqdev = &vcpu->irq.dev;
+	struct kvm_kernint *s;
+	struct kvm_irqsink apicsink;
+
+	s = kzalloc(sizeof(*s), GFP_KERNEL);
+	if (!s)
+		return -ENOMEM;
+
+	s->vcpu = vcpu;
+
+	/*
+	 * Configure the irqdevice interface
+	 */
+	irqdev->ack         = kernint_irqdev_ack;
+	irqdev->set_pin     = kernint_irqdev_set_pin;
+	irqdev->destructor  = kernint_irqdev_destructor;
+
+	irqdev->private = s;
+	s->self_irq = irqdev;
+
+	/*
+	 * Configure the EXTINT device if this is the BSP processor
+	 */
+	if (!vcpu_slot(vcpu)) {
+		struct kvm_irqsink extsink = {
+			.set_intr   = kvm_ext_intr,
+			.private    = s
+		};
+		s->ext_irq = &vcpu->kvm->isa_irq;
+		kvm_irqdevice_register_sink(s->ext_irq, &extsink);
+	}
+
+	/*
+	 * Configure the LAPIC device
+	 */
+	apicsink.set_intr = kvm_apic_intr;
+	apicsink.private  = s;
+
+	kvm_irqdevice_init(&s->apic_irq);
+	kvm_irqdevice_register_sink(&s->apic_irq, &apicsink);
+	kvm_lapic_init(vcpu, &s->apic_irq, 0);
+
+	return 0;
+}
+
diff --git a/drivers/kvm/kvm.h b/drivers/kvm/kvm.h
index e1ba066..573ae2f 100644
--- a/drivers/kvm/kvm.h
+++ b/drivers/kvm/kvm.h
@@ -165,6 +165,21 @@ int kvm_user_irqdev_init(struct kvm_irqdevice *dev);
 int kvm_user_irqdev_save(struct kvm_irqdevice *this, void *data);
 int kvm_user_irqdev_restore(struct kvm_irqdevice *this, void *data);
 int kvm_userint_init(struct kvm_vcpu *vcpu);
+int kvm_kernint_init(struct kvm_vcpu *vcpu);
+
+#define KVM_LAPIC_OPTION_USERMODE (1 << 0)
+
+int kvm_lapic_init(struct kvm_vcpu *vcpu, struct kvm_irqdevice *dev,
+		   int flags);
+void kvm_lapic_destroy(struct kvm_vcpu *vcpu);
+void kvm_lapic_set_tpr(struct kvm_vcpu *vcpu, u64 cr8);
+u64  kvm_lapic_get_tpr(struct kvm_vcpu *vcpu);
+void kvm_lapic_set_base(struct kvm_vcpu *vcpu, u64 base);
+u64  kvm_lapic_get_base(struct kvm_vcpu *vcpu);
+void kvm_lapic_save(struct kvm_vcpu *vcpu, struct kvm_sregs *sregs);
+void kvm_lapic_restore(struct kvm_vcpu *vcpu, struct kvm_sregs *sregs);
+void kvm_lapic_reset(struct kvm_vcpu *vcpu);
+int  kvm_lapic_enabled(struct kvm_vcpu *vcpu);
 
 /*
  * x86 supports 3 paging modes (4-level 64-bit, 3-level 64-bit, and 2-level
@@ -335,6 +350,11 @@ struct kvm_vcpu_irq {
 	int                  eventfd;
 };
 
+struct kvm_lapic {
+	void                 *dev;
+	struct kvm_io_device *mmio;
+};
+
 struct kvm_vcpu {
 	struct kvm *kvm;
 	union {
@@ -349,6 +369,7 @@ struct kvm_vcpu {
 	int interrupt_window_open;
 	struct kvm_vcpu_irq irq;
 	pid_t owner;
+	struct kvm_lapic apic;
 	unsigned long regs[NR_VCPU_REGS]; /* for rsp: vcpu_load_rsp_rip() */
 	unsigned long rip;      /* needs vcpu_load_rsp_rip() */
 
@@ -359,10 +380,8 @@ struct kvm_vcpu {
 	struct page *para_state_page;
 	gpa_t hypercall_gpa;
 	unsigned long cr4;
-	unsigned long cr8;
 	u64 pdptrs[4]; /* pae */
 	u64 shadow_efer;
-	u64 apic_base;
 	u64 ia32_misc_enable_msr;
 	int nmsrs;
 	struct vmx_msr_entry *guest_msrs;
@@ -539,6 +558,8 @@ struct kvm {
 	struct list_head vm_list;
 	struct file *filp;
 	struct kvm_io_bus mmio_bus;
+	int enable_kernel_pic;
+	struct kvm_irqdevice isa_irq;
 };
 
 struct descriptor_table {
@@ -613,6 +634,9 @@ void kvm_exit_arch(void);
 int kvm_mmu_module_init(void);
 void kvm_mmu_module_exit(void);
 
+int kvm_apicbus_send(struct kvm *kvm, int dest, int trig_mode, int level,
+		     int dest_mode, int delivery_mode, int vector);
+
 void kvm_mmu_destroy(struct kvm_vcpu *vcpu);
 int kvm_mmu_create(struct kvm_vcpu *vcpu);
 int kvm_mmu_setup(struct kvm_vcpu *vcpu);
@@ -746,6 +770,13 @@ static inline struct kvm_mmu_page *page_header(hpa_t shadow_page)
 	return (struct kvm_mmu_page *)page_private(page);
 }
 
+static inline int vcpu_slot(struct kvm_vcpu *vcpu)
+{
+	return vcpu - vcpu->kvm->vcpus;
+}
+
+void kvm_crash_guest(struct kvm *kvm);
+
 static inline u16 read_fs(void)
 {
 	u16 seg;
diff --git a/drivers/kvm/kvm_main.c b/drivers/kvm/kvm_main.c
index 7109b66..ee87f62 100644
--- a/drivers/kvm/kvm_main.c
+++ b/drivers/kvm/kvm_main.c
@@ -319,6 +319,7 @@ static struct kvm *kvm_create_vm(void)
 	spin_lock_init(&kvm->lock);
 	INIT_LIST_HEAD(&kvm->active_mmu_pages);
 	kvm_io_bus_init(&kvm->mmio_bus);
+	kvm_irqdevice_init(&kvm->isa_irq);
 	for (i = 0; i < KVM_MAX_VCPUS; ++i) {
 		struct kvm_vcpu *vcpu = &kvm->vcpus[i];
 
@@ -413,6 +414,23 @@ static void kvm_free_vcpus(struct kvm *kvm)
 		kvm_free_vcpu(&kvm->vcpus[i]);
 }
 
+/*
+ * The function kills a guest while there still is a user space processes
+ * with a descriptor to it
+ */
+void kvm_crash_guest(struct kvm *kvm)
+{
+	unsigned int i;
+
+	for (i = 0; i < KVM_MAX_VCPUS; ++i) {
+		/*
+		 * FIXME: in the future it should send IPI to gracefully
+		 * stop the other vCPUs
+		 */
+		kvm_free_vcpu(&kvm->vcpus[i]);
+	}
+}
+
 static int kvm_dev_release(struct inode *inode, struct file *filp)
 {
 	return 0;
@@ -424,6 +442,8 @@ static void kvm_destroy_vm(struct kvm *kvm)
 	list_del(&kvm->vm_list);
 	spin_unlock(&kvm_lock);
 	kvm_io_bus_destroy(&kvm->mmio_bus);
+	if (kvm->enable_kernel_pic)
+		kvm_irqdevice_destructor(&kvm->isa_irq);
 	kvm_free_vcpus(kvm);
 	kvm_free_physmem(kvm);
 	kfree(kvm);
@@ -629,7 +649,7 @@ void set_cr8(struct kvm_vcpu *vcpu, unsigned long cr8)
 		inject_gp(vcpu);
 		return;
 	}
-	vcpu->cr8 = cr8;
+	kvm_lapic_set_tpr(vcpu, cr8);
 }
 EXPORT_SYMBOL_GPL(set_cr8);
 
@@ -930,6 +950,69 @@ out:
 	return r;
 }
 
+static int kvm_vm_ioctl_enable_kernel_pic(struct kvm *kvm, __u32 val)
+{
+	/*
+	 * FIXME: We should not allow this if VCPUs have already been created
+	 */
+	if (kvm->enable_kernel_pic)
+		return -EINVAL;
+
+	/*
+	 * Someday we may offer two levels of in-kernel PIC support:
+	 *
+	 *  level 0 = (default) compatiblity mode (everything in userspace)
+	 *  level 1 = LAPIC in kernel, IOAPIC/i8259 in userspace
+	 *  level 2 = All three in kernel
+	 *
+	 * For now we only support level 0 and 1.  However, you cant set
+	 * level 0
+	 */
+	if (val != 1)
+		return -EINVAL;
+
+	kvm->enable_kernel_pic = val;
+
+	printk(KERN_INFO "KVM: Setting in-kernel PIC level to %d\n", val);
+
+	/*
+	 * installing a user_irqdev model to the kvm->isa_irq device
+	 * creates a level-1 environment, where the userspace completely
+	 * controls the ISA domain interrupts in the IOAPIC/i8259.
+	 * Interrupts come down to the VCPU either as an ISA vector to
+	 * this controller, or as an APIC bus message (or both)
+	 */
+	kvm_user_irqdev_init(&kvm->isa_irq);
+
+	return 0;
+}
+
+static int kvm_vm_ioctl_isa_interrupt(struct kvm *kvm,
+				      struct kvm_interrupt *irq)
+{
+	if (irq->irq < 0 || irq->irq >= 256)
+		return -EINVAL;
+
+	if (!kvm->enable_kernel_pic)
+		return -EINVAL;
+
+	return kvm_irqdevice_set_pin(&kvm->isa_irq, irq->irq, 1);
+}
+
+static int kvm_vm_ioctl_apic_msg(struct kvm *kvm,
+				 struct kvm_apic_msg *msg)
+{
+	if (!kvm->enable_kernel_pic)
+		return -EINVAL;
+
+	msg->delivery_mode = (msg->delivery_mode << 8) & 0xF00;
+
+	kvm_apicbus_send(kvm, msg->dest, msg->trig_mode, 1, msg->dest_mode,
+			 msg->delivery_mode, msg->vector);
+
+	return 0;
+}
+
 static gfn_t unalias_gfn(struct kvm *kvm, gfn_t gfn)
 {
 	int i;
@@ -1050,10 +1133,16 @@ static int emulator_write_std(unsigned long addr,
 static struct kvm_io_device *vcpu_find_mmio_dev(struct kvm_vcpu *vcpu,
 						gpa_t addr)
 {
+	struct kvm_io_device *dev = vcpu->apic.mmio;
+
+	/*
+	 * First check if the LAPIC will snarf this request
+	 */
+	if (dev && dev->in_range(dev, addr))
+		return dev;
+
 	/*
-	 * Note that its important to have this wrapper function because
-	 * in the very near future we will be checking for MMIOs against
-	 * the LAPIC as well as the general MMIO bus
+	 * And then fallback to allow any device to participate
 	 */
 	return kvm_io_bus_find_dev(&vcpu->kvm->mmio_bus, addr);
 }
@@ -1520,7 +1609,7 @@ int kvm_get_msr_common(struct kvm_vcpu *vcpu, u32 msr, u64 *pdata)
 		data = 3;
 		break;
 	case MSR_IA32_APICBASE:
-		data = vcpu->apic_base;
+		data = kvm_lapic_get_base(vcpu);
 		break;
 	case MSR_IA32_MISC_ENABLE:
 		data = vcpu->ia32_misc_enable_msr;
@@ -1598,7 +1687,7 @@ int kvm_set_msr_common(struct kvm_vcpu *vcpu, u32 msr, u64 data)
 	case 0x200 ... 0x2ff: /* MTRRs */
 		break;
 	case MSR_IA32_APICBASE:
-		vcpu->apic_base = data;
+		kvm_lapic_set_base(vcpu, data);
 		break;
 	case MSR_IA32_MISC_ENABLE:
 		vcpu->ia32_misc_enable_msr = data;
@@ -1862,8 +1951,9 @@ static int kvm_vcpu_ioctl_run(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
 	if (vcpu->sigset_active)
 		sigprocmask(SIG_SETMASK, &vcpu->sigset, &sigsaved);
 
-	/* re-sync apic's tpr */
-	vcpu->cr8 = kvm_run->cr8;
+	if (!vcpu->kvm->enable_kernel_pic)
+		/* re-sync apic's tpr if the APIC is in userspace */
+		kvm_lapic_set_tpr(vcpu, kvm_run->cr8);
 
 	if (vcpu->pio.cur_count) {
 		r = complete_pio(vcpu);
@@ -2015,11 +2105,12 @@ static int kvm_vcpu_ioctl_get_sregs(struct kvm_vcpu *vcpu,
 	sregs->cr2 = vcpu->cr2;
 	sregs->cr3 = vcpu->cr3;
 	sregs->cr4 = vcpu->cr4;
-	sregs->cr8 = vcpu->cr8;
 	sregs->efer = vcpu->shadow_efer;
-	sregs->apic_base = vcpu->apic_base;
 
-	kvm_user_irqdev_save(&vcpu->irq.dev, &sregs->interrupt_bitmap);
+	kvm_lapic_save(vcpu, sregs);
+
+	if (!vcpu->kvm->enable_kernel_pic)
+		kvm_user_irqdev_save(&vcpu->irq.dev, &sregs->interrupt_bitmap);
 
 	vcpu_put(vcpu);
 
@@ -2051,14 +2142,10 @@ static int kvm_vcpu_ioctl_set_sregs(struct kvm_vcpu *vcpu,
 	mmu_reset_needed |= vcpu->cr3 != sregs->cr3;
 	vcpu->cr3 = sregs->cr3;
 
-	vcpu->cr8 = sregs->cr8;
-
 	mmu_reset_needed |= vcpu->shadow_efer != sregs->efer;
 #ifdef CONFIG_X86_64
 	kvm_arch_ops->set_efer(vcpu, sregs->efer);
 #endif
-	vcpu->apic_base = sregs->apic_base;
-
 	kvm_arch_ops->decache_cr4_guest_bits(vcpu);
 
 	mmu_reset_needed |= vcpu->cr0 != sregs->cr0;
@@ -2072,8 +2159,11 @@ static int kvm_vcpu_ioctl_set_sregs(struct kvm_vcpu *vcpu,
 	if (mmu_reset_needed)
 		kvm_mmu_reset_context(vcpu);
 
-	kvm_user_irqdev_restore(&vcpu->irq.dev,
-				&sregs->interrupt_bitmap[0]);
+	kvm_lapic_restore(vcpu, sregs);
+
+	if (!vcpu->kvm->enable_kernel_pic)
+		kvm_user_irqdev_restore(&vcpu->irq.dev,
+					&sregs->interrupt_bitmap[0]);
 
 	set_segment(vcpu, &sregs->cs, VCPU_SREG_CS);
 	set_segment(vcpu, &sregs->ds, VCPU_SREG_DS);
@@ -2478,7 +2568,12 @@ static int kvm_vm_ioctl_create_vcpu(struct kvm *kvm, int n)
 
 	kvm_irqdevice_init(&vcpu->irq.dev);
 	kvm_vcpu_irqsink_init(vcpu);
-	r = kvm_userint_init(vcpu);
+
+	if (kvm->enable_kernel_pic)
+		r = kvm_kernint_init(vcpu);
+	else
+		r = kvm_userint_init(vcpu);
+
 	if (r < 0)
 		goto out_free_vcpus;
 
@@ -2611,6 +2706,12 @@ static int kvm_vcpu_ioctl_set_eventfd(struct kvm_vcpu *vcpu, int fd)
 	return 0;
 }
 
+static int kvm_vcpu_ioctl_apic_reset(struct kvm_vcpu *vcpu)
+{
+	kvm_lapic_reset(vcpu);
+	return 0;
+}
+
 static long kvm_vcpu_ioctl(struct file *filp,
 			   unsigned int ioctl, unsigned long arg)
 {
@@ -2789,6 +2890,13 @@ static long kvm_vcpu_ioctl(struct file *filp,
 		r = 0;
 		break;
 	}
+	case KVM_APIC_RESET: {
+		r = kvm_vcpu_ioctl_apic_reset(vcpu);
+		if (r)
+			goto out;
+		r = 0;
+		break;
+	}
 	default:
 		;
 	}
@@ -2842,6 +2950,41 @@ static long kvm_vm_ioctl(struct file *filp,
 			goto out;
 		break;
 	}
+	case KVM_ENABLE_KERNEL_PIC: {
+		__u32 val;
+
+		r = -EFAULT;
+		if (copy_from_user(&val, argp, sizeof val))
+			goto out;
+		r = kvm_vm_ioctl_enable_kernel_pic(kvm, val);
+		if (r)
+			goto out;
+		break;
+	}
+	case KVM_ISA_INTERRUPT: {
+		struct kvm_interrupt irq;
+
+		r = -EFAULT;
+		if (copy_from_user(&irq, argp, sizeof irq))
+			goto out;
+		r = kvm_vm_ioctl_isa_interrupt(kvm, &irq);
+		if (r)
+			goto out;
+		r = 0;
+		break;
+	}
+	case KVM_APIC_MSG: {
+		struct kvm_apic_msg msg;
+
+		r = -EFAULT;
+		if (copy_from_user(&msg, argp, sizeof msg))
+			goto out;
+		r = kvm_vm_ioctl_apic_msg(kvm, &msg);
+		if (r)
+			goto out;
+		r = 0;
+		break;
+	}
 	default:
 		;
 	}
@@ -2978,6 +3121,9 @@ static long kvm_dev_ioctl(struct file *filp,
 
 		switch (ext) {
 		case KVM_SET_EVENTFD:
+		case KVM_ISA_INTERRUPT:
+		case KVM_APIC_MSG:
+		case KVM_APIC_RESET:
 			r = 1;
 			break;
 		default:
diff --git a/drivers/kvm/lapic.c b/drivers/kvm/lapic.c
new file mode 100644
index 0000000..d62f56f
--- /dev/null
+++ b/drivers/kvm/lapic.c
@@ -0,0 +1,1421 @@
+/*
+ * Local APIC virtualization
+ *
+ * Copyright (C) 2006 Qumranet, Inc.
+ * Copyright (C) 2007 Novell
+ *
+ * Authors:
+ *   Dor Laor <dor.laor-atKUWr5tajBWk0Htik3J/w@public.gmane.org>
+ *   Gregory Haskins <ghaskins-Et1tbQHTxzrQT0dZR+AlfA@public.gmane.org>
+ *
+ * Based on Xen 3.0 code, Copyright (c) 2004, Intel Corporation.
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2.  See
+ * the COPYING file in the top-level directory.
+ */
+
+#include "kvm.h"
+#include <linux/kvm.h>
+#include <linux/mm.h>
+#include <linux/highmem.h>
+#include <linux/smp.h>
+#include <linux/hrtimer.h>
+#include <asm/processor.h>
+#include <asm/io.h>
+#include <asm/msr.h>
+#include <asm/page.h>
+#include <asm/current.h>
+
+/*XXX remove this definition after GFW enabled */
+#define APIC_NO_BIOS
+
+#define PRId64 "d"
+#define PRIx64 "llx"
+#define PRIu64 "u"
+#define PRIo64 "o"
+
+#define APIC_BUS_CYCLE_NS 1
+
+/* #define apic_debug(fmt,arg...) printk(KERN_WARNING fmt,##arg) */
+#define apic_debug(fmt,arg...)
+
+struct kvm_kern_apic {
+	spinlock_t              lock;
+	atomic_t                ref_count;
+	int                     usermode;
+	u32                     status;
+	u32                     vcpu_id;
+	u64                     base_msr;
+	unsigned long           base_address;
+	struct kvm_io_device    mmio_dev;
+	struct {
+		unsigned long   pending;
+		u32             divide_count;
+		ktime_t         last_update;
+		struct hrtimer  dev;
+	} timer;
+	u32                     err_status;
+	u32                     err_write_count;
+	struct kvm_vcpu         *vcpu;
+	struct kvm_irqdevice    *irq_dev;
+	struct page             *regs_page;
+	void                    *regs;
+};
+
+static __inline__ int find_highest_bit(unsigned long *data, int nr_bits)
+{
+	int length = BITS_TO_LONGS(nr_bits);
+	while (length && !data[--length])
+		continue;
+	return __ffs(data[length]) + (length * BITS_PER_LONG);
+}
+
+#define APIC_LVT_NUM			6
+/* 14 is the version for Xeon and Pentium 8.4.8*/
+#define APIC_VERSION			(0x14UL | ((APIC_LVT_NUM - 1) << 16))
+#define VLOCAL_APIC_MEM_LENGTH		(1 << 12)
+/* followed define is not in apicdef.h */
+#define APIC_SHORT_MASK			0xc0000
+#define APIC_DEST_NOSHORT		0x0
+#define APIC_DEST_MASK			0x800
+#define _APIC_GLOB_DISABLE		0x0
+#define APIC_GLOB_DISABLE_MASK		0x1
+#define APIC_SOFTWARE_DISABLE_MASK	0x2
+#define _APIC_BSP_ACCEPT_PIC		0x3
+#define MAX_APIC_INT_VECTOR             256
+
+#define inject_gp(vcpu) kvm_arch_ops->inject_gp(vcpu, 0);
+
+#define apic_enabled(apic)              \
+	(!((apic)->status &                   \
+	   (APIC_GLOB_DISABLE_MASK | APIC_SOFTWARE_DISABLE_MASK)))
+
+#define apic_global_enabled(apic)       \
+	(!(test_bit(_APIC_GLOB_DISABLE, &(apic)->status)))
+
+#define LVT_MASK \
+	APIC_LVT_MASKED | APIC_SEND_PENDING | APIC_VECTOR_MASK
+
+#define LINT_MASK   \
+	LVT_MASK | APIC_MODE_MASK | APIC_INPUT_POLARITY |\
+	APIC_LVT_REMOTE_IRR | APIC_LVT_LEVEL_TRIGGER
+
+#define KVM_APIC_ID(apic)   \
+	(GET_APIC_ID(apic_get_reg(apic, APIC_ID)))
+
+#define apic_lvt_enabled(apic, lvt_type)    \
+	(!(apic_get_reg(apic, lvt_type) & APIC_LVT_MASKED))
+
+#define apic_lvt_vector(apic, lvt_type)     \
+	(apic_get_reg(apic, lvt_type) & APIC_VECTOR_MASK)
+
+#define apic_lvt_dm(apic, lvt_type)           \
+	(apic_get_reg(apic, lvt_type) & APIC_MODE_MASK)
+
+#define apic_lvtt_period(apic)     \
+	(apic_get_reg(apic, APIC_LVTT) & APIC_LVT_TIMER_PERIODIC)
+
+static inline u32 apic_get_reg(struct kvm_kern_apic *apic, u32 reg)
+{
+	return *((u32 *)(apic->regs + reg));
+}
+
+static inline void apic_set_reg(struct kvm_kern_apic *apic,
+				u32 reg, u32 val)
+{
+	*((u32 *)(apic->regs + reg)) = val;
+}
+
+static unsigned int apic_lvt_mask[APIC_LVT_NUM] =
+{
+	LVT_MASK | APIC_LVT_TIMER_PERIODIC, 	/* LVTT */
+	LVT_MASK | APIC_MODE_MASK, 		/* LVTTHMR */
+	LVT_MASK | APIC_MODE_MASK, 		/* LVTPC */
+	LINT_MASK, LINT_MASK, 			/* LVT0-1 */
+	LVT_MASK 				/* LVTERR */
+};
+
+#define ASSERT(x)  							     \
+	if (!(x)) { 							     \
+		printk(KERN_EMERG "assertion failed %s: %d: %s\n",           \
+		       __FILE__, __LINE__, #x);                              \
+		BUG();                                                       \
+	}
+
+static int apic_find_highest_irr(struct kvm_kern_apic *apic)
+{
+	int result;
+
+	result = find_highest_bit((unsigned long *)(apic->regs + APIC_IRR),
+				  MAX_APIC_INT_VECTOR);
+
+	ASSERT( result == 0 || result >= 16);
+
+	return result;
+}
+
+
+static int apic_find_highest_isr(struct kvm_kern_apic *apic)
+{
+	int result;
+
+	result = find_highest_bit((unsigned long *)(apic->regs + APIC_ISR),
+				  MAX_APIC_INT_VECTOR);
+
+	ASSERT( result == 0 || result >= 16);
+
+	return result;
+}
+
+static void apic_dropref(struct kvm_kern_apic *apic)
+{
+	if (atomic_dec_and_test(&apic->ref_count)) {
+
+		spin_lock_bh(&apic->lock);
+
+		hrtimer_cancel(&apic->timer.dev);
+
+		if (apic->regs_page) {
+			__free_page(apic->regs_page);
+			apic->regs_page = 0;
+		}
+
+		spin_unlock_bh(&apic->lock);
+
+		kfree(apic);
+	}
+}
+
+#if 0
+static void apic_dump_state(struct kvm_kern_apic *apic)
+{
+	u64 *tmp;
+
+	printk(KERN_INFO "%s begin\n", __FUNCTION__);
+
+	printk(KERN_INFO "status = 0x%08x\n", apic->status);
+	printk(KERN_INFO "base_msr=0x%016llx, apicbase = 0x%08lx\n",
+	       apic->base_msr, apic->base_address);
+
+	tmp = (u64*)(apic->regs + APIC_IRR);
+	printk(KERN_INFO "IRR = 0x%016llx 0x%016llx 0x%016llx 0x%016llx\n",
+	       tmp[3], tmp[2], tmp[1], tmp[0]);
+	tmp = (u64*)(apic->regs + APIC_ISR);
+	printk(KERN_INFO "ISR = 0x%016llx 0x%016llx 0x%016llx 0x%016llx\n",
+	       tmp[3], tmp[2], tmp[1], tmp[0]);
+	tmp = (u64*)(apic->regs + APIC_TMR);
+	printk(KERN_INFO "TMR = 0x%016llx 0x%016llx 0x%016llx 0x%016llx\n",
+	       tmp[3], tmp[2], tmp[1], tmp[0]);
+
+	printk(KERN_INFO "APIC_ID=0x%08x\n", apic_get_reg(apic, APIC_ID));
+	printk(KERN_INFO "APIC_TASKPRI=0x%08x\n",
+	       apic_get_reg(apic, APIC_TASKPRI) & 0xff);
+	printk(KERN_INFO "APIC_PROCPRI=0x%08x\n",
+	       apic_get_reg(apic, APIC_PROCPRI));
+
+	printk(KERN_INFO "APIC_DFR=0x%08x\n",
+	       apic_get_reg(apic, APIC_DFR) | 0x0FFFFFFF);
+	printk(KERN_INFO "APIC_LDR=0x%08x\n",
+	       apic_get_reg(apic, APIC_LDR) & APIC_LDR_MASK);
+	printk(KERN_INFO "APIC_SPIV=0x%08x\n",
+	       apic_get_reg(apic, APIC_SPIV) & 0x3ff);
+	printk(KERN_INFO "APIC_ESR=0x%08x\n",
+	       apic_get_reg(apic, APIC_ESR));
+	printk(KERN_INFO "APIC_ICR=0x%08x\n",
+	       apic_get_reg(apic, APIC_ICR) & ~(1 << 12));
+	printk(KERN_INFO "APIC_ICR2=0x%08x\n",
+	       apic_get_reg(apic, APIC_ICR2) & 0xff000000);
+
+	printk(KERN_INFO "APIC_LVTERR=0x%08x\n",
+	       apic_get_reg(apic, APIC_LVTERR));
+	printk(KERN_INFO "APIC_LVT1=0x%08x\n",
+	       apic_get_reg(apic, APIC_LVT1));
+	printk(KERN_INFO "APIC_LVT0=0x%08x\n",
+	       apic_get_reg(apic, APIC_LVT0));
+	printk(KERN_INFO "APIC_LVTPC=0x%08x\n",
+	       apic_get_reg(apic, APIC_LVTPC));
+	printk(KERN_INFO "APIC_LVTTHMR=0x%08x\n",
+	       apic_get_reg(apic, APIC_LVTTHMR));
+	printk(KERN_INFO "APIC_LVTT=0x%08x\n",
+	       apic_get_reg(apic, APIC_LVTT));
+
+	printk(KERN_INFO "APIC_TMICT=0x%08x\n",
+	       apic_get_reg(apic, APIC_TMICT));
+	printk(KERN_INFO "APIC_TDCR=0x%08x\n",
+	       apic_get_reg(apic, APIC_TDCR));
+
+	printk(KERN_INFO "%s end\n", __FUNCTION__);
+}
+#endif
+
+
+static int apic_update_ppr(struct kvm_kern_apic *apic)
+{
+	u32 tpr, isrv, ppr, orig_ppr;
+	int irq;
+	int masked = 0;
+	int forward = 0;
+
+	ppr = apic_get_reg(apic, APIC_PROCPRI);
+	orig_ppr = ppr;
+
+	/*
+	 * Before we change anything, see if the only pending vectors we have
+	 * are anything masked by PPR
+	 */
+	irq = apic_find_highest_irr(apic);
+	if (irq && ((irq & 0xf0) <= ppr))
+		masked = true;
+
+	/*
+	 * Compute the PPR value based on the current settings of TPR/ISR
+	 */
+	tpr = apic_get_reg(apic, APIC_TASKPRI);
+	irq = apic_find_highest_isr(apic);
+	isrv = (irq >> 4) & 0xf;
+
+	if ((tpr >> 4) >= isrv)
+		ppr = tpr & 0xff;
+	else
+		ppr = isrv << 4;  /* low 4 bits of PPR have to be cleared */
+
+	apic_set_reg(apic, APIC_PROCPRI, ppr);
+
+	if (masked) {
+		/*
+		 * If we get here its because there were vectors that
+		 * were masked by PPR.  Check again to see if anything is
+		 * now available
+		 */
+		irq = apic_find_highest_irr(apic);
+		if ((irq & 0xf0) > ppr)
+			forward = 1;
+	}
+
+	apic_debug("%s: ppr 0x%x (old) 0x%x (new), isr 0x%x, isrv 0x%x\n",
+	       __FUNCTION__, orig_ppr, ppr, irq, isrv);
+
+	return forward;
+}
+
+static void apic_set_tpr(struct kvm_kern_apic *apic, u32 tpr)
+{
+	int forward = 0;
+
+	apic_debug("new value = %x\n", tpr);
+
+	apic_set_reg(apic, APIC_TASKPRI, tpr);
+	forward = apic_update_ppr(apic);
+
+	if (forward) {
+		spin_unlock_bh(&apic->lock);
+		kvm_irqdevice_set_intr(apic->irq_dev, kvm_irqpin_localint);
+		spin_lock_bh(&apic->lock);
+	}
+}
+
+static int apic_match_dest(struct kvm_kern_apic *target,
+			   int dest,
+			   int dest_mode,
+			   int delivery_mode)
+{
+	int result = 0;
+
+	spin_lock_bh(&target->lock);
+
+	if (!dest_mode) /* Physical */
+		result = (GET_APIC_ID(apic_get_reg(target, APIC_ID)) == dest);
+	else { /* Logical */
+		u32 ldr = apic_get_reg(target, APIC_LDR);
+
+		/* Flat mode */
+		if (apic_get_reg(target, APIC_DFR) == APIC_DFR_FLAT)
+			result = GET_APIC_LOGICAL_ID(ldr) & dest;
+		else {
+			if ((delivery_mode == APIC_DM_LOWEST) &&
+			    (dest == 0xff)) {
+				printk(KERN_ALERT "Broadcast IPI " \
+				       "with lowest priority "
+				       "delivery mode\n");
+				spin_unlock_bh(&target->lock);
+				kvm_crash_guest(target->vcpu->kvm);
+				return 0;
+			}
+			if (GET_APIC_LOGICAL_ID(ldr) == (dest & 0xf))
+				result = (GET_APIC_LOGICAL_ID(ldr) >> 4) &
+					(dest >> 4);
+			else
+				result = 0;
+		}
+	}
+
+	spin_unlock_bh(&target->lock);
+
+	return result;
+}
+
+/*
+ * Add a pending IRQ into lapic.
+ * Return 1 if successfully added and 0 if discarded.
+ */
+static int __apic_accept_irq(struct kvm_kern_apic *apic,
+			     int delivery_mode,
+			     int vector,
+			     int level,
+			     int trig_mode)
+{
+	kvm_irqpin_t pin = kvm_irqpin_invalid;
+
+	switch (delivery_mode) {
+	case APIC_DM_FIXED:
+	case APIC_DM_LOWEST:
+		if (unlikely(!apic_enabled(apic)))
+			break;
+
+		if (test_and_set_bit(vector, apic->regs + APIC_IRR)
+		    && trig_mode) {
+			apic_debug("level trig mode repeatedly for vector " \
+				   "%d\n", vector);
+			break;
+		}
+
+		if (trig_mode) {
+			apic_debug("level trig mode for vector %d\n", vector);
+			set_bit(vector, apic->regs + APIC_TMR);
+		}
+
+		apic_debug("FIXED/LOWEST interrupt for vector %d\n", vector);
+		pin = kvm_irqpin_localint;
+		break;
+	case APIC_DM_REMRD:
+		printk(KERN_WARNING "%s: Ignore deliver mode %d\n",
+		       __FUNCTION__, delivery_mode);
+		break;
+	case APIC_DM_EXTINT:
+		apic_debug("EXTINT interrupt\n");
+		pin  = kvm_irqpin_extint;
+		break;
+	case APIC_DM_SMI:
+		apic_debug("SMI interrupt\n");
+		pin = kvm_irqpin_smi;
+		break;
+	case APIC_DM_NMI:
+		apic_debug("NMI interrupt\n");
+		pin = kvm_irqpin_nmi;
+		break;
+	case APIC_DM_INIT:
+		apic_debug("INIT interrupt\n");
+		if (level) {
+			spin_unlock_bh(&apic->lock);
+			kvm_lapic_reset(apic->vcpu);
+			spin_lock_bh(&apic->lock);
+		}
+		break;
+	case APIC_DM_STARTUP: /* FIXME: currently no support for SMP */
+	default:
+		printk(KERN_ALERT "TODO: support interrupt type %x\n",
+		       delivery_mode);
+		spin_unlock_bh(&apic->lock);
+		kvm_crash_guest(apic->vcpu->kvm);
+		spin_lock_bh(&apic->lock);
+		break;
+	}
+
+	if (likely(pin != kvm_irqpin_invalid)) {
+		/*
+		 * temp release of the lock to transmit
+		 */
+		spin_unlock_bh(&apic->lock);
+		kvm_irqdevice_set_intr(apic->irq_dev, pin);
+		spin_lock_bh(&apic->lock);
+
+		return 1;
+	} else
+		return 0;
+}
+
+static int apic_accept_irq(struct kvm_kern_apic *apic,
+			   int delivery_mode,
+			   int vector,
+			   int level,
+			   int trig_mode)
+{
+	int ret;
+
+	spin_lock_bh(&apic->lock);
+	ret = __apic_accept_irq(apic, delivery_mode, vector,
+				level, trig_mode);
+	spin_unlock_bh(&apic->lock);
+
+	return ret;
+}
+
+static void apic_set_eoi(struct kvm_kern_apic *apic)
+{
+	int vector = apic_find_highest_isr(apic);
+	int forward;
+
+	/*
+	 * Not every write EOI will has corresponding ISR,
+	 * one example is when Kernel check timer on setup_IO_APIC
+	 */
+	if (!vector)
+		return;
+
+	__clear_bit(vector, apic->regs + APIC_ISR);
+	forward = apic_update_ppr(apic);
+
+	__clear_bit(vector, apic->regs + APIC_TMR);
+
+	if (forward) {
+		spin_unlock_bh(&apic->lock);
+		kvm_irqdevice_set_intr(apic->irq_dev, kvm_irqpin_localint);
+		spin_lock_bh(&apic->lock);
+	}
+}
+
+static int apic_check_vector(struct kvm_kern_apic *apic,u32 dm, u32 vector)
+{
+	if ((dm == APIC_DM_FIXED) && (vector < 16)) {
+		apic->err_status |= 0x40;
+		__apic_accept_irq(apic, APIC_DM_FIXED,
+				  apic_lvt_vector(apic, APIC_LVTERR), 0, 0);
+		apic_debug("%s: check failed "
+		       " dm %x vector %x\n", __FUNCTION__, dm, vector);
+		return 0;
+	}
+	return 1;
+}
+
+int kvm_apicbus_send(struct kvm *kvm, int dest, int trig_mode, int level,
+		     int dest_mode, int delivery_mode, int vector)
+{
+	int i;
+	u32 lpr_map = 0;
+
+	apic_debug("%s: %d %d %d %d %d %d\n", __FUNCTION__,
+		   dest, trig_mode, level, dest_mode, delivery_mode, vector);
+
+	for (i = 0; i < KVM_MAX_VCPUS; ++i) {
+		struct kvm_kern_apic *target;
+		target = kvm->vcpus[i].apic.dev;
+
+		if (!target)
+			continue;
+
+		if (apic_match_dest(target, dest, dest_mode, delivery_mode)) {
+			if (delivery_mode == APIC_DM_LOWEST)
+				__set_bit(target->vcpu_id, &lpr_map);
+			else
+				apic_accept_irq(target, delivery_mode,
+						vector, level, trig_mode);
+		}
+	}
+
+	if (delivery_mode == APIC_DM_LOWEST) {
+		struct kvm_kern_apic *target;
+
+		/* Currently only UP is supported */
+		target = kvm->vcpus[0].apic.dev;
+
+		if (target)
+			apic_accept_irq(target, delivery_mode,
+					vector, level, trig_mode);
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(kvm_apicbus_send);
+
+static void apic_send_ipi(struct kvm_kern_apic *apic)
+{
+	u32 icr_low = apic_get_reg(apic, APIC_ICR);
+	u32 icr_high = apic_get_reg(apic, APIC_ICR2);
+
+	unsigned int dest =          GET_APIC_DEST_FIELD(icr_high);
+	unsigned int short_hand =    icr_low & APIC_SHORT_MASK;
+	unsigned int trig_mode =     icr_low & APIC_INT_LEVELTRIG;
+	unsigned int level =         icr_low & APIC_INT_ASSERT;
+	unsigned int dest_mode =     icr_low & APIC_DEST_MASK;
+	unsigned int delivery_mode = icr_low & APIC_MODE_MASK;
+	unsigned int vector =        icr_low & APIC_VECTOR_MASK;
+
+	apic_debug("icr_high 0x%x, icr_low 0x%x, "
+		 "short_hand 0x%x, dest 0x%x, trig_mode 0x%x, level 0x%x, "
+		 "dest_mode 0x%x, delivery_mode 0x%x, vector 0x%x\n",
+		 icr_high, icr_low, short_hand, dest,
+		 trig_mode, level, dest_mode, delivery_mode, vector);
+
+	/*
+	 * We unlock here because we would enter this function in a lock
+	 * state and we dont want to remain this way while we transmit
+	 */
+	spin_unlock_bh(&apic->lock);
+
+	if (short_hand == APIC_DEST_NOSHORT)
+		/*
+		 * If no short-hand notation is in use, just forward the
+		 * message onto the apicbus and let the bus handle the routing.
+		 */
+		kvm_apicbus_send(apic->vcpu->kvm, dest, trig_mode, level,
+				 dest_mode, delivery_mode, vector);
+	else {
+		/*
+		 * Otherwise we need to consider the short-hand to find the
+		 * correct targets.
+		 */
+		unsigned int i;
+
+		for (i = 0; i < KVM_MAX_VCPUS; ++i) {
+			struct kvm_kern_apic *target;
+			int result = 0;
+
+			target = apic->vcpu->kvm->vcpus[i].apic.dev;
+
+			if (!target)
+				continue;
+
+			switch (short_hand) {
+			case APIC_DEST_SELF:
+				if (target == apic)
+					result = 1;
+				break;
+			case APIC_DEST_ALLINC:
+				result = 1;
+				break;
+
+			case APIC_DEST_ALLBUT:
+				if (target != apic)
+					result = 1;
+				break;
+			}
+
+			if (result)
+				apic_accept_irq(target, delivery_mode,
+						vector, level, trig_mode);
+		}
+	}
+
+	/*
+	 * Relock before returning
+	 */
+	spin_lock_bh(&apic->lock);
+
+}
+
+static u32 apic_get_tmcct(struct kvm_kern_apic *apic)
+{
+	u32 counter_passed;
+	ktime_t passed, now = apic->timer.dev.base->get_time();
+	u32 tmcct = apic_get_reg(apic, APIC_TMCCT);
+
+	ASSERT(apic != NULL);
+
+	if (unlikely(ktime_to_ns(now) <=
+		     ktime_to_ns(apic->timer.last_update))) {
+		/* Wrap around */
+		passed = ktime_add(
+			({ (ktime_t){
+				.tv64 = KTIME_MAX -
+					 (apic->timer.last_update).tv64 };
+			}), now);
+		apic_debug("time elapsed\n");
+	} else
+		passed = ktime_sub(now, apic->timer.last_update);
+
+	counter_passed = ktime_to_ns(passed) /
+		(APIC_BUS_CYCLE_NS * apic->timer.divide_count);
+	tmcct -= counter_passed;
+
+	if (tmcct <= 0) {
+		if (unlikely(!apic_lvtt_period(apic))) {
+			tmcct =  0;
+		} else {
+			do {
+				tmcct += apic_get_reg(apic, APIC_TMICT);
+			} while ( tmcct <= 0 );
+		}
+	}
+
+	apic->timer.last_update = now;
+	apic_set_reg(apic, APIC_TMCCT, tmcct);
+
+	return tmcct;
+}
+
+/*
+ *----------------------------------------------------------------------
+ * MMIO
+ *----------------------------------------------------------------------
+ */
+
+#define align(val, len) (val & ~(len-1))
+
+static int validate_mmio(struct kvm_kern_apic *apic, gpa_t address, int len)
+{
+	/*
+	 * According to IA 32 Manual, all registers should be accessed with
+	 * 32 bits alignment.
+	 */
+	if (align(address, 4) != align(address+(len-1), 4)) {
+		printk(KERN_WARNING "KVM: MMIO request for %d bytes at " \
+		       "0x%lx is not 32 bit aligned.  Injecting #GP\n",
+		       len, address);
+		inject_gp(apic->vcpu);
+		return 0;
+	}
+
+	return 1;
+}
+
+static u32 __apic_read(struct kvm_kern_apic *apic,
+				unsigned int offset)
+{
+	u32 val = 0;
+
+	if (offset > APIC_TDCR)
+		return 0;
+
+	switch (offset) {
+	case APIC_ARBPRI:
+		printk(KERN_WARNING "access local APIC ARBPRI register " \
+		       "which is for P6\n");
+		break;
+
+	case APIC_TMCCT:        /* Timer CCR */
+		val = apic_get_tmcct(apic);
+		break;
+
+	case APIC_ESR:
+		apic->err_write_count = 0;
+		/* fall through */
+	default:
+		val = apic_get_reg(apic, offset);
+		break;
+	}
+
+	return val;
+}
+
+static void apic_mmio_read(struct kvm_io_device *this,
+			   gpa_t address,
+			   int len,
+			   void *data)
+{
+	struct kvm_kern_apic *apic = (struct kvm_kern_apic*)this->private;
+	unsigned int          offset = address - apic->base_address;
+	unsigned char         alignment = offset & 0x3;
+	u32                   val;
+
+	if (!validate_mmio(apic, address, len))
+		return;
+
+	spin_lock_bh(&apic->lock);
+	val = __apic_read(apic, offset & ~0x3);
+	spin_unlock_bh(&apic->lock);
+
+	switch (len) {
+	case 1:
+	case 2:
+	case 4:
+		memcpy(data, (char*)((char*)&val + alignment), len);
+		break;
+	default:
+		printk(KERN_ALERT "Local APIC read with len = %x, " \
+		       "should be 1,2, or 4 instead\n", len);
+		inject_gp(apic->vcpu);
+		break;
+	}
+}
+
+static void apic_mmio_write(struct kvm_io_device *this,
+			    gpa_t address,
+			    int len,
+			    const void *data)
+{
+	struct kvm_kern_apic *apic = (struct kvm_kern_apic*)this->private;
+	unsigned int          offset = address - apic->base_address;
+	unsigned char         alignment = offset & 0x3;
+	u32                   val;
+
+	if (!validate_mmio(apic, address, len))
+		return;
+
+	spin_lock_bh(&apic->lock);
+
+	switch (len) {
+	case 1:
+	case 2: {
+		unsigned int tmp;
+
+		/*
+		 * Some kernels will access with byte/word alignment
+		 */
+		apic_debug("Notice: Local APIC write with len = %x\n", len);
+		tmp = __apic_read(apic, offset & ~0x3);
+		switch (len) {
+		case 1:
+			val = *(u8*)data;
+
+			val = (tmp & ~(0xff << (8*alignment))) |
+			      ((val & 0xff) << (8*alignment));
+			break;
+
+		case 2:
+			if (alignment != 0x0 && alignment != 0x2) {
+				printk(KERN_ALERT "alignment error for apic " \
+				       "with len == 2\n");
+				inject_gp(apic->vcpu);
+			}
+
+			/*
+			 * assumes 16 bit alignment on the pointer.
+			 * Mis-alignment is a host-side issue, however, so
+			 * we crash
+			 */
+			BUG_ON(((long)data & 0x1));
+
+			val = *(u16*)data;
+
+			val = (tmp & ~(0xffff << (8*alignment))) |
+			      ((val & 0xffff) << (8*alignment));
+			break;
+		}
+
+		break;
+	}
+	case 4:
+		memcpy(&val, data, 4);
+		break;
+	default:
+		printk(KERN_ALERT "Local APIC write with len = %x, " \
+		       "should be 1,2, or 4 instead\n", len);
+		inject_gp(apic->vcpu);
+		break;
+	}
+
+	/* too common printing */
+	if (offset != APIC_EOI)
+		apic_debug("%s: offset 0x%x with length 0x%x, and value is " \
+			 "0x%lx\n",
+		       __FUNCTION__, offset, len, val);
+
+	offset &= 0xff0;
+
+	switch (offset) {
+	case APIC_ID:   /* Local APIC ID */
+		apic_set_reg(apic, APIC_ID, val);
+		break;
+
+	case APIC_TASKPRI:
+		apic_set_tpr(apic, val & 0xff);
+		break;
+
+	case APIC_EOI:
+		apic_set_eoi(apic);
+		break;
+
+	case APIC_LDR:
+		apic_set_reg(apic, APIC_LDR, val & APIC_LDR_MASK);
+		break;
+
+	case APIC_DFR:
+		apic_set_reg(apic, APIC_DFR, val | 0x0FFFFFFF);
+		break;
+
+	case APIC_SPIV:
+		apic_set_reg(apic, APIC_SPIV, val & 0x3ff);
+		if (!(val & APIC_SPIV_APIC_ENABLED)) {
+			int i;
+			u32 lvt_val;
+
+			apic->status |= APIC_SOFTWARE_DISABLE_MASK;
+			for (i = 0; i < APIC_LVT_NUM; i++) {
+				lvt_val = apic_get_reg(apic,
+							   APIC_LVTT +
+							   0x10 * i);
+				apic_set_reg(apic, APIC_LVTT + 0x10 * i,
+						 lvt_val | APIC_LVT_MASKED);
+			}
+
+			if ((apic_get_reg(apic, APIC_LVT0) &
+			     APIC_MODE_MASK) == APIC_DM_EXTINT)
+				clear_bit(_APIC_BSP_ACCEPT_PIC, &apic->status);
+		} else {
+			apic->status &= ~APIC_SOFTWARE_DISABLE_MASK;
+			if ((apic_get_reg(apic, APIC_LVT0) &
+			     APIC_MODE_MASK) == APIC_DM_EXTINT)
+				set_bit(_APIC_BSP_ACCEPT_PIC, &apic->status);
+		}
+		break;
+
+	case APIC_ESR:
+		apic->err_write_count = !apic->err_write_count;
+		if (!apic->err_write_count)
+			apic->err_status = 0;
+		break;
+
+	case APIC_ICR:
+		/* No delay here, so we always clear the pending bit*/
+		apic_set_reg(apic, APIC_ICR, val & ~(1 << 12));
+		apic_send_ipi(apic);
+		break;
+
+	case APIC_ICR2:
+		apic_set_reg(apic, APIC_ICR2, val & 0xff000000);
+		break;
+
+	case APIC_LVTT:
+	case APIC_LVTTHMR:
+	case APIC_LVTPC:
+	case APIC_LVT0:
+	case APIC_LVT1:
+	case APIC_LVTERR:
+	{
+		if (apic->status & APIC_SOFTWARE_DISABLE_MASK)
+			val |= APIC_LVT_MASKED;
+
+		val &= apic_lvt_mask[(offset - APIC_LVTT) >> 4];
+		apic_set_reg(apic, offset, val);
+
+		/* On hardware, when write vector less than 0x20 will error */
+		if (!(val & APIC_LVT_MASKED))
+			apic_check_vector(apic, apic_lvt_dm(apic, offset),
+					  apic_lvt_vector(apic, offset));
+		if (!apic->vcpu_id && (offset == APIC_LVT0)) {
+			if ((val & APIC_MODE_MASK) == APIC_DM_EXTINT)
+				if (val & APIC_LVT_MASKED)
+					clear_bit(_APIC_BSP_ACCEPT_PIC,
+						  &apic->status);
+				else
+					set_bit(_APIC_BSP_ACCEPT_PIC,
+						&apic->status);
+			else
+				clear_bit(_APIC_BSP_ACCEPT_PIC,
+					  &apic->status);
+		}
+	}
+		break;
+
+	case APIC_TMICT:
+	{
+		ktime_t now = apic->timer.dev.base->get_time();
+		u32 offset;
+
+		apic_set_reg(apic, APIC_TMICT, val);
+		apic_set_reg(apic, APIC_TMCCT, val);
+		apic->timer.last_update = now;
+		offset = APIC_BUS_CYCLE_NS * apic->timer.divide_count * val;
+
+		/* Make sure the lock ordering is coherent */
+		spin_unlock_bh(&apic->lock);
+		hrtimer_cancel(&apic->timer.dev);
+		hrtimer_start(&apic->timer.dev,
+			      ktime_add_ns(now, offset),
+			      HRTIMER_MODE_ABS);
+
+		apic_debug("%s: bus cycle is %"PRId64"ns, now 0x%016"PRIx64", "
+			 "timer initial count 0x%x, offset 0x%x, "
+			 "expire @ 0x%016"PRIx64".\n", __FUNCTION__,
+			 APIC_BUS_CYCLE_NS, ktime_to_ns(now),
+			 apic_get_reg(apic, APIC_TMICT),
+			 offset, ktime_to_ns(ktime_add_ns(now, offset)));
+	}
+		return;
+
+	case APIC_TDCR:
+	{
+		unsigned int tmp1, tmp2;
+
+		tmp1 = val & 0xf;
+		tmp2 = ((tmp1 & 0x3) | ((tmp1 & 0x8) >> 1)) + 1;
+		apic->timer.divide_count = 0x1 << (tmp2 & 0x7);
+
+		apic_set_reg(apic, APIC_TDCR, val);
+
+		apic_debug("timer divide count is 0x%x\n",
+		       apic->timer.divide_count);
+	}
+		break;
+
+	default:
+		printk(KERN_WARNING "Local APIC Write to read-only register\n");
+		break;
+	}
+
+	spin_unlock_bh(&apic->lock);
+}
+
+static int apic_mmio_range(struct kvm_io_device *this, gpa_t addr)
+{
+	struct kvm_kern_apic *apic = (struct kvm_kern_apic*)this->private;
+	int ret = 0;
+
+	spin_lock_bh(&apic->lock);
+
+	if (apic_global_enabled(apic) &&
+	    (addr >= apic->base_address) &&
+	    (addr < (apic->base_address + VLOCAL_APIC_MEM_LENGTH)))
+		ret = 1;
+
+	spin_unlock_bh(&apic->lock);
+
+	return ret;
+}
+
+static void apic_mmio_destructor(struct kvm_io_device *this)
+{
+	struct kvm_kern_apic *apic = (struct kvm_kern_apic*)this->private;
+
+	apic_dropref(apic);
+}
+
+static void apic_mmio_register(struct kvm_kern_apic *apic)
+{
+	/* Register ourselves with the MMIO subsystem */
+	struct kvm_io_device *dev = &apic->mmio_dev;
+
+	dev->read       = apic_mmio_read;
+	dev->write      = apic_mmio_write;
+	dev->in_range   = apic_mmio_range;
+	dev->destructor = apic_mmio_destructor;
+
+	dev->private = apic;
+	atomic_inc(&apic->ref_count);
+
+	apic->vcpu->apic.mmio = dev;
+}
+
+/*
+ *----------------------------------------------------------------------
+ * LAPIC interface
+ *----------------------------------------------------------------------
+ */
+
+void kvm_lapic_set_tpr(struct kvm_vcpu *vcpu, u64 cr8)
+{
+	struct kvm_kern_apic *apic = (struct kvm_kern_apic*)vcpu->apic.dev;
+
+	spin_lock_bh(&apic->lock);
+	apic_set_tpr(apic, ((cr8 & 0x0f) << 4));
+	spin_unlock_bh(&apic->lock);
+}
+
+u64 kvm_lapic_get_tpr(struct kvm_vcpu *vcpu)
+{
+	struct kvm_kern_apic *apic = (struct kvm_kern_apic*)vcpu->apic.dev;
+	u64 tpr;
+
+	spin_lock_bh(&apic->lock);
+	tpr = (u64)apic_get_reg(apic, APIC_TASKPRI);
+	spin_unlock_bh(&apic->lock);
+
+	return (tpr & 0xf0) >> 4;
+}
+EXPORT_SYMBOL_GPL(kvm_lapic_get_tpr);
+
+void kvm_lapic_set_base(struct kvm_vcpu *vcpu, u64 value)
+{
+	struct kvm_kern_apic *apic = (struct kvm_kern_apic*)vcpu->apic.dev;
+
+	spin_lock_bh(&apic->lock);
+	if (apic->vcpu_id)
+		value &= ~MSR_IA32_APICBASE_BSP;
+
+	apic->base_msr = value;
+	apic->base_address = apic->base_msr & MSR_IA32_APICBASE_BASE;
+
+	/* with FSB delivery interrupt, we can restart APIC functionality */
+	if (!(value & MSR_IA32_APICBASE_ENABLE))
+		set_bit(_APIC_GLOB_DISABLE, &apic->status);
+	else
+		clear_bit(_APIC_GLOB_DISABLE, &apic->status);
+
+	apic_debug("apic base msr is 0x%016"PRIx64", and base address is " \
+		 "0x%lx.\n", apic->base_msr, apic->base_address);
+
+	spin_unlock_bh(&apic->lock);
+}
+
+u64 kvm_lapic_get_base(struct kvm_vcpu *vcpu)
+{
+	struct kvm_kern_apic *apic = (struct kvm_kern_apic*)vcpu->apic.dev;
+	u64 base;
+
+	spin_lock_bh(&apic->lock);
+	base = apic->base_msr;
+	spin_unlock_bh(&apic->lock);
+
+	return base;
+}
+EXPORT_SYMBOL_GPL(kvm_lapic_get_base);
+
+void kvm_lapic_save(struct kvm_vcpu *vcpu, struct kvm_sregs *sregs)
+{
+	/*
+	 * FIXME: This needs to support the entire register set when
+	 * enabled
+	 */
+	sregs->cr8       = kvm_lapic_get_tpr(vcpu);
+	sregs->apic_base = kvm_lapic_get_base(vcpu);
+}
+
+void kvm_lapic_restore(struct kvm_vcpu *vcpu, struct kvm_sregs *sregs)
+{
+	/*
+	 * FIXME: This needs to support the entire register set when
+	 * enabled
+	 */
+	kvm_lapic_set_tpr(vcpu, sregs->cr8);
+	kvm_lapic_set_base(vcpu, sregs->apic_base);
+}
+
+void kvm_lapic_reset(struct kvm_vcpu *vcpu)
+{
+	struct kvm_kern_apic *apic;
+	int i;
+
+	apic_debug("%s\n", __FUNCTION__);
+
+	ASSERT(vcpu);
+	apic = vcpu->apic.dev;
+	ASSERT(apic != NULL);
+
+	/* Stop the timer in case it's a reset to an active apic */
+	hrtimer_cancel(&apic->timer.dev);
+
+	spin_lock_bh(&apic->lock);
+
+	apic_set_reg(apic, APIC_ID, vcpu_slot(vcpu) << 24);
+	apic_set_reg(apic, APIC_LVR, APIC_VERSION);
+
+	for (i = 0; i < APIC_LVT_NUM; i++)
+		apic_set_reg(apic, APIC_LVTT + 0x10 * i, APIC_LVT_MASKED);
+
+	apic_set_reg(apic, APIC_DFR, 0xffffffffU);
+	apic_set_reg(apic, APIC_SPIV, 0xff);
+	apic_set_reg(apic, APIC_TASKPRI, 0);
+	apic_set_reg(apic, APIC_LDR, 0);
+	apic_set_reg(apic, APIC_ESR, 0);
+	apic_set_reg(apic, APIC_ICR, 0);
+	apic_set_reg(apic, APIC_ICR2, 0);
+	apic_set_reg(apic, APIC_TDCR, 0);
+	apic_set_reg(apic, APIC_TMICT, 0);
+	memset((void*)(apic->regs + APIC_IRR), 0, KVM_IRQ_BITMAP_SIZE(u8));
+	memset((void*)(apic->regs + APIC_ISR), 0, KVM_IRQ_BITMAP_SIZE(u8));
+	memset((void*)(apic->regs + APIC_TMR), 0, KVM_IRQ_BITMAP_SIZE(u8));
+
+	apic->base_msr =
+		MSR_IA32_APICBASE_ENABLE |
+		APIC_DEFAULT_PHYS_BASE;
+	if (vcpu_slot(vcpu) == 0)
+		apic->base_msr |= MSR_IA32_APICBASE_BSP;
+	apic->base_address = apic->base_msr & MSR_IA32_APICBASE_BASE;
+
+	apic->timer.divide_count = 0;
+	apic->timer.pending = 0;
+	apic->status = 0;
+
+#ifdef APIC_NO_BIOS
+	/*
+	 * XXX According to mp specification, BIOS will enable LVT0/1,
+	 * remove it after BIOS enabled
+	 */
+	if (!vcpu_slot(vcpu)) {
+		apic_set_reg(apic, APIC_LVT0, APIC_MODE_EXTINT << 8);
+		apic_set_reg(apic, APIC_LVT1, APIC_MODE_NMI << 8);
+		set_bit(_APIC_BSP_ACCEPT_PIC, &apic->status);
+	}
+#endif
+
+	spin_unlock_bh(&apic->lock);
+
+	printk(KERN_INFO  "%s: vcpu=%p, id=%d, base_msr=" \
+	       "0x%016"PRIx64", base_address=0x%0lx.\n", __FUNCTION__, vcpu,
+	       GET_APIC_ID(apic_get_reg(apic, APIC_ID)),
+	       apic->base_msr, apic->base_address);
+}
+
+int kvm_lapic_enabled(struct kvm_vcpu *vcpu)
+{
+	struct kvm_kern_apic *apic = (struct kvm_kern_apic*)vcpu->apic.dev;
+	int ret = 0;
+
+	spin_lock_bh(&apic->lock);
+	if (!apic->usermode)
+		ret = apic_enabled(apic);
+	spin_unlock_bh(&apic->lock);
+
+	return ret;
+}
+
+/*
+ *----------------------------------------------------------------------
+ * timer interface
+ *----------------------------------------------------------------------
+ */
+static int __apic_timer_fn(struct kvm_kern_apic *apic)
+{
+	u32 vector;
+	ktime_t now;
+	int result = 0;
+
+	if (unlikely(!apic_enabled(apic) ||
+		     !apic_lvt_enabled(apic, APIC_LVTT))) {
+		apic_debug("%s: time interrupt although apic is down\n",
+			 __FUNCTION__);
+		return 0;
+	}
+
+	vector                  = apic_lvt_vector(apic, APIC_LVTT);
+	now                     = apic->timer.dev.base->get_time();
+	apic->timer.last_update = now;
+	apic->timer.pending++;
+
+	__apic_accept_irq(apic, APIC_DM_FIXED, vector, 1, 0);
+
+	if (apic_lvtt_period(apic)) {
+		u32 offset;
+		u32 tmict = apic_get_reg(apic, APIC_TMICT);
+
+		apic_set_reg(apic, APIC_TMCCT, tmict);
+		offset = APIC_BUS_CYCLE_NS * apic->timer.divide_count * tmict;
+
+		result = 1;
+		apic->timer.dev.expires = ktime_add_ns(now, offset);
+
+		apic_debug("%s: now 0x%016"PRIx64", expire @ 0x%016"PRIx64", "
+		       "timer initial count 0x%x, timer current count 0x%x.\n",
+		       __FUNCTION__,
+		       ktime_to_ns(now), ktime_add_ns(now, offset),
+		       apic_get_reg(apic, APIC_TMICT),
+	               apic_get_reg(apic, APIC_TMCCT));
+	} else {
+		apic_set_reg(apic, APIC_TMCCT, 0);
+		apic_debug("%s: now 0x%016"PRIx64", "
+		       "timer initial count 0x%x, timer current count 0x%x.\n",
+		       __FUNCTION__,
+		       ktime_to_ns(now), apic_get_reg(apic, APIC_TMICT),
+		       apic_get_reg(apic, APIC_TMCCT));
+	}
+
+	return result;
+}
+
+static enum hrtimer_restart apic_timer_fn(struct hrtimer *data)
+{
+	struct kvm_kern_apic *apic;
+	int restart_timer = 0;
+
+	apic = container_of(data, struct kvm_kern_apic, timer.dev);
+
+	spin_lock_bh(&apic->lock);
+	restart_timer = __apic_timer_fn(apic);
+	spin_unlock_bh(&apic->lock);
+
+	if (restart_timer)
+		return HRTIMER_RESTART;
+	else
+		return HRTIMER_NORESTART;
+}
+
+/*
+ *----------------------------------------------------------------------
+ * IRQDEVICE interface
+ *----------------------------------------------------------------------
+ */
+
+static int apic_irqdev_ack(struct kvm_irqdevice *this, int flags,
+			   struct kvm_irqack_data *data)
+{
+	struct kvm_kern_apic *apic = (struct kvm_kern_apic*)this->private;
+	int irq;
+
+	apic_debug("LAPIC ACK attempt\n");
+
+	spin_lock_bh(&apic->lock);
+
+	if (!apic_enabled(apic))
+		goto out;
+
+	if (!(flags & KVM_IRQACK_FLAG_PEEK)) {
+		irq = apic_find_highest_irr(apic);
+		if ((irq & 0xf0) > apic_get_reg(apic, APIC_PROCPRI)) {
+			BUG_ON (irq < 0x10);
+
+			__set_bit(irq, apic->regs + APIC_ISR);
+			__clear_bit(irq, apic->regs + APIC_IRR);
+			apic_update_ppr(apic);
+
+			/*
+			 * We have to special case the timer interrupt
+			 * because we want the vector to stay pending
+			 * for each tick of the clock, even for a backlog.
+			 * Therefore, if this was a timer vector and we
+			 * still have ticks pending, keep IRR set
+			 */
+			if (irq == apic_lvt_vector(apic, APIC_LVTT)) {
+				BUG_ON(!apic->timer.pending);
+				apic->timer.pending--;
+				if (apic->timer.pending)
+					__set_bit(irq, apic->regs + APIC_IRR);
+			}
+
+			data->flags |= KVM_IRQACKDATA_VECTOR_VALID;
+			data->vector = irq;
+		}
+		else
+			data->vector = -1;
+
+		apic_debug("ACK for vector %d\n", data->vector);
+	}
+
+	/*
+	 * See if there is anything still pending.  Don't forget that we may
+	 * have entered this function with vector=NULL just to check pending
+	 * status
+	 */
+	irq = apic_find_highest_irr(apic);
+	if (irq) {
+		/*
+		 * we check TASKPRI (as opposed to PROCPRI) because we
+		 * want to know the threshold against which the CPU is masking
+		 * interrupts, not the APIC itself.  The PROCPRI register
+		 * factors in the ISR in addition to the TPR.  Therefore, we
+		 * would never see a match here if we looked at PPR since
+		 * we just injected the highest ISR during this call
+		 */
+		if ((irq & 0xf0) > apic_get_reg(apic, APIC_TASKPRI))
+			data->flags |= KVM_IRQACKDATA_VECTOR_PENDING;
+	}
+
+ out:
+	spin_unlock_bh(&apic->lock);
+
+	return 0;
+}
+
+static int apic_irqdev_set_pin(struct kvm_irqdevice *this, int irq, int level)
+{
+	struct kvm_kern_apic *apic = (struct kvm_kern_apic*)this->private;
+	int lvt = 0;
+
+	spin_lock_bh(&apic->lock);
+
+	if (!apic_enabled(apic)) {
+		/*
+		 * If the LAPIC is disabled, we simply forward the interrupt
+		 * on to the output line
+		 */
+		__apic_accept_irq(apic, APIC_DM_EXTINT, 0, level, 1);
+		goto out;
+	}
+
+	/*
+	 * pin "0" is LINT0, and "1" is LINT1
+	 */
+	BUG_ON(irq > 1);
+
+	switch(irq) {
+	case 0:
+		lvt = APIC_LVT0;
+		break;
+	case 1:
+		lvt = APIC_LVT1;
+		break;
+	}
+
+	if (apic_lvt_enabled(apic, lvt))
+		__apic_accept_irq(apic,
+				  apic_lvt_dm(apic, lvt),
+				  apic_lvt_vector(apic, lvt),
+				  level,
+				  1);
+
+
+ out:
+	spin_unlock_bh(&apic->lock);
+
+	return 0;
+}
+
+static void apic_irqdev_destructor(struct kvm_irqdevice *this)
+{
+	struct kvm_kern_apic *apic = (struct kvm_kern_apic*)this->private;
+
+	apic_dropref(apic);
+}
+
+static void apic_irqdev_register(struct kvm_kern_apic *apic,
+				 struct kvm_irqdevice *dev)
+{
+	dev->ack         = apic_irqdev_ack;
+	dev->set_pin     = apic_irqdev_set_pin;
+	dev->destructor  = apic_irqdev_destructor;
+
+	dev->private = apic;
+	atomic_inc(&apic->ref_count);
+
+	apic->irq_dev = dev;
+}
+
+int kvm_lapic_init(struct kvm_vcpu *vcpu,
+		   struct kvm_irqdevice *irq_dev, int flags)
+{
+	struct kvm_kern_apic *apic = NULL;
+	struct kvm_io_device *mmio_dev = NULL;
+
+	ASSERT(vcpu != NULL);
+	apic_debug("apic_init %d\n", vcpu_slot(vcpu));
+
+	apic = kzalloc(sizeof(*apic), GFP_KERNEL);
+	if (!apic)
+		goto nomem;
+
+	spin_lock_init(&apic->lock);
+	atomic_inc(&apic->ref_count);
+	apic->vcpu_id = vcpu_slot(vcpu);
+
+	apic->regs_page = alloc_page(GFP_KERNEL);
+	if ( apic->regs_page == NULL ) {
+		printk(KERN_ALERT "malloc apic regs error for vcpu %x\n",
+		       vcpu_slot(vcpu));
+		goto nomem;
+	}
+	apic->regs = page_address(apic->regs_page);
+	memset(apic->regs, 0, PAGE_SIZE);
+
+	apic->vcpu = vcpu;
+	vcpu->apic.dev = apic;
+
+	if (!(flags & KVM_LAPIC_OPTION_USERMODE)) {
+		apic_irqdev_register(apic, irq_dev);
+		apic_mmio_register(apic);
+	} else
+		apic->usermode = 1;
+
+	hrtimer_init(&apic->timer.dev, CLOCK_MONOTONIC, HRTIMER_MODE_ABS);
+	apic->timer.dev.function = apic_timer_fn;
+
+	kvm_lapic_reset(vcpu);
+	return 0;
+
+ nomem:
+	if (mmio_dev)
+		kfree(mmio_dev);
+
+	if (apic)
+		apic_dropref(apic);
+
+	return -ENOMEM;
+}
+
+void kvm_lapic_destroy(struct kvm_vcpu *vcpu)
+{
+	struct kvm_kern_apic *apic = vcpu->apic.dev;
+
+	if (vcpu->apic.mmio)
+		kvm_iodevice_destructor(vcpu->apic.mmio);
+
+	apic_dropref(apic);
+}
diff --git a/drivers/kvm/svm.c b/drivers/kvm/svm.c
index 6c6228d..78b9f8f 100644
--- a/drivers/kvm/svm.c
+++ b/drivers/kvm/svm.c
@@ -570,9 +570,6 @@ static int svm_create_vcpu(struct kvm_vcpu *vcpu)
 
 	fx_init(vcpu);
 	vcpu->fpu_active = 1;
-	vcpu->apic_base = 0xfee00000 |
-			/*for vcpu 0*/ MSR_IA32_APICBASE_BSP |
-			MSR_IA32_APICBASE_ENABLE;
 
 	return 0;
 
@@ -1410,9 +1407,9 @@ static void do_intr_requests(struct kvm_vcpu *vcpu,
 			r = kvm_vcpu_irq_pop(vcpu, &ack);
 			break;
 		case kvm_irqpin_extint:
-			printk(KERN_WARNING "KVM: external-interrupts not " \
-			       "handled yet\n");
-			__clear_bit(pin, &vcpu->irq.pending);
+			r = kvm_irqdevice_ack(&vcpu->kvm->isa_irq, 0, &ack);
+			if (!(ack.flags & KVM_IRQACKDATA_VECTOR_PENDING))
+				__clear_bit(pin, &vcpu->irq.pending);
 			break;
 		case kvm_irqpin_nmi:
 			/*
@@ -1501,8 +1498,8 @@ static void post_kvm_run_save(struct kvm_vcpu *vcpu,
 		(vcpu->interrupt_window_open &&
 		 !kvm_vcpu_irq_pending(vcpu));
 	kvm_run->if_flag = (vcpu->svm->vmcb->save.rflags & X86_EFLAGS_IF) != 0;
-	kvm_run->cr8 = vcpu->cr8;
-	kvm_run->apic_base = vcpu->apic_base;
+	kvm_run->cr8 = kvm_lapic_get_tpr(vcpu);
+	kvm_run->apic_base = kvm_lapic_get_base(vcpu);
 }
 
 /*
diff --git a/drivers/kvm/userint.c b/drivers/kvm/userint.c
index a60707d..c6118b0 100644
--- a/drivers/kvm/userint.c
+++ b/drivers/kvm/userint.c
@@ -218,6 +218,12 @@ int kvm_user_irqdev_restore(struct kvm_irqdevice *this, void *data)
 
 int kvm_userint_init(struct kvm_vcpu *vcpu)
 {
-	return kvm_user_irqdev_init(&vcpu->irq.dev);
+	int ret;
+
+	ret = kvm_user_irqdev_init(&vcpu->irq.dev);
+	if (ret < 0)
+		return ret;
+
+	return kvm_lapic_init(vcpu, NULL, KVM_LAPIC_OPTION_USERMODE);
 }
 
diff --git a/drivers/kvm/vmx.c b/drivers/kvm/vmx.c
index 543c27e..580b99f 100644
--- a/drivers/kvm/vmx.c
+++ b/drivers/kvm/vmx.c
@@ -1196,10 +1196,6 @@ static int vmx_vcpu_setup(struct kvm_vcpu *vcpu)
 
 	memset(vcpu->regs, 0, sizeof(vcpu->regs));
 	vcpu->regs[VCPU_REGS_RDX] = get_rdx_init_val();
-	vcpu->cr8 = 0;
-	vcpu->apic_base = 0xfee00000 |
-			/*for vcpu 0*/ MSR_IA32_APICBASE_BSP |
-			MSR_IA32_APICBASE_ENABLE;
 
 	fx_init(vcpu);
 
@@ -1441,9 +1437,9 @@ static void do_intr_requests(struct kvm_vcpu *vcpu,
 			r = kvm_vcpu_irq_pop(vcpu, &ack);
 			break;
 		case kvm_irqpin_extint:
-			printk(KERN_WARNING "KVM: external-interrupts not " \
-			       "handled yet\n");
-			__clear_bit(pin, &vcpu->irq.pending);
+			r = kvm_irqdevice_ack(&vcpu->kvm->isa_irq, 0, &ack);
+			if (!(ack.flags & KVM_IRQACKDATA_VECTOR_PENDING))
+				__clear_bit(pin, &vcpu->irq.pending);
 			break;
 		case kvm_irqpin_nmi:
 			/*
@@ -1800,7 +1796,7 @@ static int handle_cr(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
 			return 1;
 		case 8:
 			vcpu_load_rsp_rip(vcpu);
-			vcpu->regs[reg] = vcpu->cr8;
+			vcpu->regs[reg] = kvm_lapic_get_tpr(vcpu);
 			vcpu_put_rsp_rip(vcpu);
 			skip_emulated_instruction(vcpu);
 			return 1;
@@ -1897,8 +1893,8 @@ static void post_kvm_run_save(struct kvm_vcpu *vcpu,
 			      struct kvm_run *kvm_run)
 {
 	kvm_run->if_flag = (vmcs_readl(GUEST_RFLAGS) & X86_EFLAGS_IF) != 0;
-	kvm_run->cr8 = vcpu->cr8;
-	kvm_run->apic_base = vcpu->apic_base;
+	kvm_run->cr8 = kvm_lapic_get_tpr(vcpu);
+	kvm_run->apic_base = kvm_lapic_get_base(vcpu);
 	kvm_run->ready_for_interrupt_injection =
 		(vcpu->interrupt_window_open &&
 		 !kvm_vcpu_irq_pending(vcpu));
diff --git a/include/linux/kvm.h b/include/linux/kvm.h
index f13ec8c..300e212 100644
--- a/include/linux/kvm.h
+++ b/include/linux/kvm.h
@@ -231,6 +231,17 @@ struct kvm_dirty_log {
 	};
 };
 
+/* for KVM_APIC */
+struct kvm_apic_msg {
+	/* in */
+	__u32 dest;
+	__u32 trig_mode;
+	__u32 dest_mode;
+	__u32 delivery_mode;
+	__u32 vector;
+	__u32 padding;
+};
+
 struct kvm_cpuid_entry {
 	__u32 function;
 	__u32 eax;
@@ -282,6 +293,9 @@ struct kvm_signal_mask {
 #define KVM_CREATE_VCPU           _IO(KVMIO,  0x41)
 #define KVM_GET_DIRTY_LOG         _IOW(KVMIO, 0x42, struct kvm_dirty_log)
 #define KVM_SET_MEMORY_ALIAS      _IOW(KVMIO, 0x43, struct kvm_memory_alias)
+#define KVM_ENABLE_KERNEL_PIC     _IOW(KVMIO, 0x44, __u32)
+#define KVM_ISA_INTERRUPT         _IOW(KVMIO, 0x45, struct kvm_interrupt)
+#define KVM_APIC_MSG		  _IOW(KVMIO, 0x46, struct kvm_apic_msg)
 
 /*
  * ioctls for vcpu fds
@@ -301,5 +315,6 @@ struct kvm_signal_mask {
 #define KVM_GET_FPU               _IOR(KVMIO,  0x8c, struct kvm_fpu)
 #define KVM_SET_FPU               _IOW(KVMIO,  0x8d, struct kvm_fpu)
 #define KVM_SET_EVENTFD           _IO(KVMIO,   0x8e)
+#define KVM_APIC_RESET		  _IO(KVMIO,   0x8f)
 
 #endif


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[PATCH 7/9] KVM: Adds support for real NMI injection on VMX processors

[Gregory Haskins]

Signed-off-by: Gregory Haskins <ghaskins-Et1tbQHTxzrQT0dZR+AlfA@public.gmane.org>
---

 drivers/kvm/vmx.c |   57 ++++++++++++++++++++++++++++++++++++++++++++++++-----
 drivers/kvm/vmx.h |    3 +++
 2 files changed, 55 insertions(+), 5 deletions(-)

diff --git a/drivers/kvm/vmx.c b/drivers/kvm/vmx.c
index 580b99f..26c6dc6 100644
--- a/drivers/kvm/vmx.c
+++ b/drivers/kvm/vmx.c
@@ -1261,7 +1261,14 @@ static int vmx_vcpu_setup(struct kvm_vcpu *vcpu)
 			       PIN_BASED_VM_EXEC_CONTROL,
 			       PIN_BASED_EXT_INTR_MASK   /* 20.6.1 */
 			       | PIN_BASED_NMI_EXITING   /* 20.6.1 */
+			       | PIN_BASED_VIRTUAL_NMI   /* 20.6.1 */
 			);
+
+	if (!(vmcs_read32(PIN_BASED_VM_EXEC_CONTROL) & PIN_BASED_VIRTUAL_NMI))
+		printk(KERN_DEBUG "KVM: Warning - Host processor does " \
+		       "not support virtual-NMI injection.  Using IRQ " \
+		       "method\n");
+ 
 	vmcs_write32_fixedbits(MSR_IA32_VMX_PROCBASED_CTLS,
 			       CPU_BASED_VM_EXEC_CONTROL,
 			       CPU_BASED_HLT_EXITING         /* 20.6.2 */
@@ -1411,6 +1418,37 @@ static void inject_rmode_irq(struct kvm_vcpu *vcpu, int irq)
 	vmcs_writel(GUEST_RSP, (vmcs_readl(GUEST_RSP) & ~0xffff) | (sp - 6));
 }
 
+static void do_nmi_requests(struct kvm_vcpu *vcpu)
+{
+	int nmi_window = 0;
+
+	BUG_ON(!(test_bit(kvm_irqpin_nmi, &vcpu->irq.pending)));
+
+	nmi_window =
+		(((vmcs_read32(GUEST_INTERRUPTIBILITY_INFO) & 0xb) == 0)
+		 && (vmcs_read32(VM_ENTRY_INTR_INFO_FIELD)
+		     & INTR_INFO_VALID_MASK));
+
+	if (nmi_window) {
+		if (vcpu->rmode.active)
+			inject_rmode_irq(vcpu, 2);
+		else
+			vmcs_write32(VM_ENTRY_INTR_INFO_FIELD,
+				     2 |
+				     INTR_TYPE_NMI |
+				     INTR_INFO_VALID_MASK);
+
+		__clear_bit(kvm_irqpin_nmi, &vcpu->irq.pending);
+	} else {
+		/*
+		 * NMIs blocked.  Wait for unblock.
+		 */
+		u32 cbvec = vmcs_read32(CPU_BASED_VM_EXEC_CONTROL);
+		cbvec |= CPU_BASED_NMI_EXITING;
+		vmcs_write32(CPU_BASED_VM_EXEC_CONTROL, cbvec);	
+	}
+}
+
 static void do_intr_requests(struct kvm_vcpu *vcpu,
 			    struct kvm_run *kvm_run,
 			    kvm_irqpin_t pin)
@@ -1443,9 +1481,11 @@ static void do_intr_requests(struct kvm_vcpu *vcpu,
 			break;
 		case kvm_irqpin_nmi:
 			/*
-			 * FIXME: Someday we will handle this using the
-			 * specific VMX NMI features.  For now, just inject
-			 * the NMI as a standard interrupt on vector 2
+			 * We should only get here if the processor does
+			 * not support virtual NMIs.  Inject the NMI as a
+			 * standard interrupt on vector 2.  The implication is
+			 * that NMIs are going to be subject to RFLAGS.IF
+			 * masking, unfortunately.
 			 */
 			ack.flags |= KVM_IRQACKDATA_VECTOR_VALID;
 			ack.vector = 2;
@@ -1488,7 +1528,8 @@ static void do_intr_requests(struct kvm_vcpu *vcpu,
 static void clear_pending_controls(struct kvm_vcpu *vcpu)
 {
 	u32 cbvec = vmcs_read32(CPU_BASED_VM_EXEC_CONTROL);
-	cbvec &= ~CPU_BASED_VIRTUAL_INTR_PENDING;
+	cbvec &= ~(CPU_BASED_VIRTUAL_INTR_PENDING
+		   | CPU_BASED_NMI_EXITING);
 	vmcs_write32(CPU_BASED_VM_EXEC_CONTROL, cbvec);
 }
 
@@ -1505,7 +1546,6 @@ static void do_interrupt_requests(struct kvm_vcpu *vcpu,
 		switch (pin) {
 		case kvm_irqpin_localint:
 		case kvm_irqpin_extint:
-		case kvm_irqpin_nmi:
 			do_intr_requests(vcpu, kvm_run, pin);
 			break;
 		case kvm_irqpin_smi:
@@ -1513,6 +1553,13 @@ static void do_interrupt_requests(struct kvm_vcpu *vcpu,
 			printk(KERN_WARNING "KVM: dropping unhandled SMI\n");
 			__clear_bit(pin, &vcpu->irq.pending);
 			break;
+		case kvm_irqpin_nmi:
+			if (vmcs_read32(PIN_BASED_VM_EXEC_CONTROL)
+			    & PIN_BASED_VIRTUAL_NMI)
+				do_nmi_requests(vcpu);
+			else
+				do_intr_requests(vcpu, kvm_run, pin);	
+			break;
 		case kvm_irqpin_invalid:
 			/* drop */
 			break;
diff --git a/drivers/kvm/vmx.h b/drivers/kvm/vmx.h
index d0dc93d..d3fe017 100644
--- a/drivers/kvm/vmx.h
+++ b/drivers/kvm/vmx.h
@@ -35,6 +35,7 @@
 #define CPU_BASED_CR8_LOAD_EXITING      0x00080000
 #define CPU_BASED_CR8_STORE_EXITING     0x00100000
 #define CPU_BASED_TPR_SHADOW            0x00200000
+#define CPU_BASED_NMI_EXITING           0x00400000
 #define CPU_BASED_MOV_DR_EXITING        0x00800000
 #define CPU_BASED_UNCOND_IO_EXITING     0x01000000
 #define CPU_BASED_ACTIVATE_IO_BITMAP    0x02000000
@@ -44,6 +45,7 @@
 
 #define PIN_BASED_EXT_INTR_MASK 0x1
 #define PIN_BASED_NMI_EXITING   0x8
+#define PIN_BASED_VIRTUAL_NMI   0x20
 
 #define VM_EXIT_ACK_INTR_ON_EXIT        0x00008000
 #define VM_EXIT_HOST_ADD_SPACE_SIZE     0x00000200
@@ -221,6 +223,7 @@ enum vmcs_field {
 #define VECTORING_INFO_VALID_MASK       	INTR_INFO_VALID_MASK
 
 #define INTR_TYPE_EXT_INTR              (0 << 8) /* external interrupt */
+#define INTR_TYPE_NMI                   (2 << 8) /* non-maskable interrupt */
 #define INTR_TYPE_EXCEPTION             (3 << 8) /* processor exception */
 
 /*


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[PATCH 8/9] KVM: Adds basic plumbing to support TPR shadow features

[Gregory Haskins]

Signed-off-by: Gregory Haskins <ghaskins-Et1tbQHTxzrQT0dZR+AlfA@public.gmane.org>
---

 drivers/kvm/irqdevice.h |    3 +++
 drivers/kvm/kvm.h       |    1 +
 drivers/kvm/lapic.c     |   15 +++++++++++++++
 3 files changed, 19 insertions(+), 0 deletions(-)

diff --git a/drivers/kvm/irqdevice.h b/drivers/kvm/irqdevice.h
index 097d179..173313d 100644
--- a/drivers/kvm/irqdevice.h
+++ b/drivers/kvm/irqdevice.h
@@ -45,12 +45,14 @@ struct kvm_irqsink {
 
 #define KVM_IRQACKDATA_VECTOR_VALID   (1 << 0)
 #define KVM_IRQACKDATA_VECTOR_PENDING (1 << 1)
+#define KVM_IRQACKDATA_NEXT_VALID     (1 << 2)
 
 #define KVM_IRQACK_FLAG_PEEK          (1 << 0)
 
 struct kvm_irqack_data {
 	int flags;
 	int vector;
+	int next;
 };
 
 struct kvm_irqdevice {
@@ -92,6 +94,7 @@ static inline void kvm_irqdevice_init(struct kvm_irqdevice *dev)
  *               data.flags -
  *                  [KVM_IRQACKDATA_VECTOR_VALID - data.vector is valid]
  *                  [KVM_IRQACKDATA_VECTOR_PENDING - more vectors are pending]
+ *                  [KVM_IRQACKDATA_NEXT_VALID - next-vector is valid]
  *
  * Returns: (int)
  *   [-1 = failure]
diff --git a/drivers/kvm/kvm.h b/drivers/kvm/kvm.h
index 573ae2f..a48e833 100644
--- a/drivers/kvm/kvm.h
+++ b/drivers/kvm/kvm.h
@@ -180,6 +180,7 @@ void kvm_lapic_save(struct kvm_vcpu *vcpu, struct kvm_sregs *sregs);
 void kvm_lapic_restore(struct kvm_vcpu *vcpu, struct kvm_sregs *sregs);
 void kvm_lapic_reset(struct kvm_vcpu *vcpu);
 int  kvm_lapic_enabled(struct kvm_vcpu *vcpu);
+void *kvm_lapic_get_regs(struct kvm_vcpu *vcpu);
 
 /*
  * x86 supports 3 paging modes (4-level 64-bit, 3-level 64-bit, and 2-level
diff --git a/drivers/kvm/lapic.c b/drivers/kvm/lapic.c
index d62f56f..ec7cb41 100644
--- a/drivers/kvm/lapic.c
+++ b/drivers/kvm/lapic.c
@@ -1149,6 +1149,13 @@ int kvm_lapic_enabled(struct kvm_vcpu *vcpu)
 	return ret;
 }
 
+void *kvm_lapic_get_regs(struct kvm_vcpu *vcpu)
+{
+	struct kvm_kern_apic *apic = (struct kvm_kern_apic*)vcpu->apic.dev;
+	return apic->regs;
+}
+EXPORT_SYMBOL_GPL(kvm_lapic_get_regs);
+
 /*
  *----------------------------------------------------------------------
  * timer interface
@@ -1287,6 +1294,14 @@ static int apic_irqdev_ack(struct kvm_irqdevice *this, int flags,
 		 */
 		if ((irq & 0xf0) > apic_get_reg(apic, APIC_TASKPRI))
 			data->flags |= KVM_IRQACKDATA_VECTOR_PENDING;
+
+		/*
+		 * We report the next pending vector here so that the system
+		 * can asses TPR thresholds for TPR-shadowing purposes
+		 * (if applicable)
+		 */
+		data->next   = irq;
+		data->flags |= KVM_IRQACKDATA_NEXT_VALID;
 	}
 
  out:


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[PATCH 9/9] KVM: Add statistics from interrupt subsystem

[Gregory Haskins]

Signed-off-by: Gregory Haskins <ghaskins-Et1tbQHTxzrQT0dZR+AlfA@public.gmane.org>
---

 drivers/kvm/kvm.h      |    5 +++++
 drivers/kvm/kvm_main.c |   17 +++++++++++++++--
 drivers/kvm/vmx.c      |    2 ++
 3 files changed, 22 insertions(+), 2 deletions(-)

diff --git a/drivers/kvm/kvm.h b/drivers/kvm/kvm.h
index a48e833..2c10952 100644
--- a/drivers/kvm/kvm.h
+++ b/drivers/kvm/kvm.h
@@ -276,6 +276,11 @@ struct kvm_stat {
 	u32 request_irq_exits;
 	u32 irq_exits;
 	u32 light_exits;
+	u32 irq_posted;
+	u32 irq_accepted;
+	u32 guest_preempt;
+	u32 apic_mmio;
+	u32 local_mmio;
 };
 
 struct kvm_io_device {
diff --git a/drivers/kvm/kvm_main.c b/drivers/kvm/kvm_main.c
index ee87f62..aeacadf 100644
--- a/drivers/kvm/kvm_main.c
+++ b/drivers/kvm/kvm_main.c
@@ -73,6 +73,11 @@ static struct kvm_stats_debugfs_item {
 	{ "request_irq", STAT_OFFSET(request_irq_exits) },
 	{ "irq_exits", STAT_OFFSET(irq_exits) },
 	{ "light_exits", STAT_OFFSET(light_exits) },
+	{ "irq_posted", STAT_OFFSET(irq_posted) },
+	{ "irq_accepted", STAT_OFFSET(irq_accepted) },
+	{ "guest_preempt", STAT_OFFSET(guest_preempt) },
+	{ "apic_mmio", STAT_OFFSET(apic_mmio) },
+	{ "local_mmio", STAT_OFFSET(local_mmio) },
 	{ NULL }
 };
 
@@ -1138,13 +1143,19 @@ static struct kvm_io_device *vcpu_find_mmio_dev(struct kvm_vcpu *vcpu,
 	/*
 	 * First check if the LAPIC will snarf this request
 	 */
-	if (dev && dev->in_range(dev, addr))
+	if (dev && dev->in_range(dev, addr)) {
+		++vcpu->stat.apic_mmio;
 		return dev;
+	}
 
 	/*
 	 * And then fallback to allow any device to participate
 	 */
-	return kvm_io_bus_find_dev(&vcpu->kvm->mmio_bus, addr);
+	dev = kvm_io_bus_find_dev(&vcpu->kvm->mmio_bus, addr);
+	if (dev)
+		++vcpu->stat.local_mmio;
+
+	return dev;
 }
 
 static int emulator_read_emulated(unsigned long addr,
@@ -2459,6 +2470,7 @@ static void kvm_vcpu_intr(struct kvm_irqsink *this,
 		 * Record the change..
 		 */
 		__set_bit(pin, &vcpu->irq.pending);
+		++vcpu->stat.irq_posted;
 
 		/*
 		 * then wake up the vcpu (if necessary)
@@ -2472,6 +2484,7 @@ static void kvm_vcpu_intr(struct kvm_irqsink *this,
 				 */
 				direct_ipi = vcpu->irq.guest_cpu;
 				BUG_ON(direct_ipi == smp_processor_id());
+				++vcpu->stat.guest_preempt;
 			} else
 				/*
 				 * otherwise, we must assume that we could be
diff --git a/drivers/kvm/vmx.c b/drivers/kvm/vmx.c
index 26c6dc6..8cfadaf 100644
--- a/drivers/kvm/vmx.c
+++ b/drivers/kvm/vmx.c
@@ -1506,6 +1506,8 @@ static void do_intr_requests(struct kvm_vcpu *vcpu,
 					     ack.vector |
 					     INTR_TYPE_EXT_INTR |
 					     INTR_INFO_VALID_MASK);
+
+			++vcpu->stat.irq_accepted;
 		}
 	}
 


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[PATCH 0/9] in-kernel APIC v4 (kernel side)

[Gregory Haskins]

This release incorporates v3, plus the following:

1) Avi's review comments have been added
2) Minor cleanup to the interrupt handling code
3) Conversion to eventfd userspace signaling mechanism

Has been tested on 

A) 32 bit Windows XP w/ACPI
B) 64 bit Linux (2.6.16 based)

Userspace will follow after this.

Regards,
-Greg

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[PATCH 5/9] KVM: Adds ability to signal userspace using a file-descriptor

[Gregory Haskins]

Signed-off-by: Gregory Haskins <ghaskins-Et1tbQHTxzrQT0dZR+AlfA@public.gmane.org>
---

 drivers/kvm/kvm.h      |    1 +
 drivers/kvm/kvm_main.c |   52 ++++++++++++++++++++++++++++++++++++++++++------
 include/linux/kvm.h    |    1 +
 3 files changed, 48 insertions(+), 6 deletions(-)

diff --git a/drivers/kvm/kvm.h b/drivers/kvm/kvm.h
index 7b5d5e6..f5731c4 100644
--- a/drivers/kvm/kvm.h
+++ b/drivers/kvm/kvm.h
@@ -333,6 +333,7 @@ struct kvm_vcpu_irq {
 	int                  deferred;
 	struct task_struct  *task;
 	int                  guest_mode;
+	int                  eventfd;
 };
 
 struct kvm_vcpu {
diff --git a/drivers/kvm/kvm_main.c b/drivers/kvm/kvm_main.c
index cb73763..86e4262 100644
--- a/drivers/kvm/kvm_main.c
+++ b/drivers/kvm/kvm_main.c
@@ -40,6 +40,7 @@
 #include <linux/file.h>
 #include <linux/fs.h>
 #include <linux/mount.h>
+#include <linux/eventfd.h>
 
 #include "x86_emulate.h"
 #include "segment_descriptor.h"
@@ -326,6 +327,7 @@ static struct kvm *kvm_create_vm(void)
 		memset(&vcpu->irq, 0, sizeof(vcpu->irq));
 		spin_lock_init(&vcpu->irq.lock);
 		vcpu->irq.deferred = -1;
+		vcpu->irq.eventfd   = -1;
 
 		vcpu->cpu = -1;
 		vcpu->kvm = kvm;
@@ -2358,6 +2360,7 @@ static void kvm_vcpu_intr(struct kvm_irqsink *this,
 {
 	struct kvm_vcpu *vcpu = (struct kvm_vcpu*)this->private;
 	int direct_ipi = -1;
+	int eventfd = -1;
 
 	spin_lock_irq(&vcpu->irq.lock);
 
@@ -2379,7 +2382,14 @@ static void kvm_vcpu_intr(struct kvm_irqsink *this,
 				 */
 				direct_ipi = task_cpu(vcpu->irq.task);
 				BUG_ON(direct_ipi == smp_processor_id());
-			}
+			} else
+				/*
+				 * otherwise, we must assume that we could be
+				 * blocked anywhere, including userspace. Send
+				 * a signal to give everyone a chance to get
+				 * notification
+				 */
+				eventfd = vcpu->irq.eventfd;
 		}
 	}
 
@@ -2401,6 +2411,12 @@ static void kvm_vcpu_intr(struct kvm_irqsink *this,
 		smp_call_function_single(direct_ipi,
 					 kvm_vcpu_guest_intr,
 					 vcpu, 0, 0);
+
+	if (eventfd != -1) {
+		struct file *filp = eventfd_fget(eventfd);
+		if (!IS_ERR(filp))
+			eventfd_signal(filp, 1);
+	}
 }
 
 static void kvm_vcpu_irqsink_init(struct kvm_vcpu *vcpu)
@@ -2584,6 +2600,14 @@ static int kvm_vcpu_ioctl_set_fpu(struct kvm_vcpu *vcpu, struct kvm_fpu *fpu)
 	return 0;
 }
 
+static int kvm_vcpu_ioctl_set_eventfd(struct kvm_vcpu *vcpu, int fd)
+{
+	vcpu->irq.eventfd = fd;
+	smp_wmb();
+
+	return 0;
+}
+
 static long kvm_vcpu_ioctl(struct file *filp,
 			   unsigned int ioctl, unsigned long arg)
 {
@@ -2753,6 +2777,15 @@ static long kvm_vcpu_ioctl(struct file *filp,
 		r = 0;
 		break;
 	}
+	case KVM_SET_EVENTFD: {
+		int eventfd = (long)argp;
+
+		r = kvm_vcpu_ioctl_set_eventfd(vcpu, eventfd);
+		if (r)
+			goto out;
+		r = 0;
+		break;
+	}
 	default:
 		;
 	}
@@ -2937,12 +2970,19 @@ static long kvm_dev_ioctl(struct file *filp,
 		r = 0;
 		break;
 	}
-	case KVM_CHECK_EXTENSION:
-		/*
-		 * No extensions defined at present.
-		 */
-		r = 0;
+	case KVM_CHECK_EXTENSION: {
+		int ext = (long)argp;
+
+		switch (ext) {
+		case KVM_SET_EVENTFD:
+			r = 1;
+			break;
+		default:
+			r = 0;
+			break;
+		}
 		break;
+	}
 	case KVM_GET_VCPU_MMAP_SIZE:
 		r = -EINVAL;
 		if (arg)
diff --git a/include/linux/kvm.h b/include/linux/kvm.h
index e6edca8..f13ec8c 100644
--- a/include/linux/kvm.h
+++ b/include/linux/kvm.h
@@ -300,5 +300,6 @@ struct kvm_signal_mask {
 #define KVM_SET_SIGNAL_MASK       _IOW(KVMIO,  0x8b, struct kvm_signal_mask)
 #define KVM_GET_FPU               _IOR(KVMIO,  0x8c, struct kvm_fpu)
 #define KVM_SET_FPU               _IOW(KVMIO,  0x8d, struct kvm_fpu)
+#define KVM_SET_EVENTFD           _IO(KVMIO,   0x8e)
 
 #endif


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Re: [PATCH 5/9] KVM: Adds ability to signal userspace using a file-descriptor

[Avi Kivity]

Gregory Haskins wrote:
> Signed-off-by: Gregory Haskins <ghaskins-Et1tbQHTxzrQT0dZR+AlfA@public.gmane.org>
> ---
>
>  drivers/kvm/kvm.h      |    1 +
>  drivers/kvm/kvm_main.c |   52 ++++++++++++++++++++++++++++++++++++++++++------
>  include/linux/kvm.h    |    1 +
>  3 files changed, 48 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/kvm/kvm.h b/drivers/kvm/kvm.h
> index 7b5d5e6..f5731c4 100644
> --- a/drivers/kvm/kvm.h
> +++ b/drivers/kvm/kvm.h
> @@ -333,6 +333,7 @@ struct kvm_vcpu_irq {
>  	int                  deferred;
>  	struct task_struct  *task;
>  	int                  guest_mode;
> +	int                  eventfd;
>   

Best to convert the fd to a filp when you install it.  This avoids the
conversion during runtime and allows you to do error checking earlier.

-- 
Do not meddle in the internals of kernels, for they are subtle and quick to panic.


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Re: [PATCH 5/9] KVM: Adds ability to signal userspace using a file-descriptor

[Gregory Haskins]

>>> On Tue, May 15, 2007 at  3:45 AM, in message <4649650E.2070102-atKUWr5tajBWk0Htik3J/w@public.gmane.org>,
Avi Kivity <avi-atKUWr5tajBWk0Htik3J/w@public.gmane.org> wrote: 
> Gregory Haskins wrote:
>> Signed- off- by: Gregory Haskins <ghaskins-Et1tbQHTxzrQT0dZR+AlfA@public.gmane.org>
>> ---
>>
>>  drivers/kvm/kvm.h      |    1 +
>>  drivers/kvm/kvm_main.c |   52 ++++++++++++++++++++++++++++++++++++++++++------
>>  include/linux/kvm.h    |    1 +
>>  3 files changed, 48 insertions(+), 6 deletions(- )
>>
>> diff -- git a/drivers/kvm/kvm.h b/drivers/kvm/kvm.h
>> index 7b5d5e6..f5731c4 100644
>> ---  a/drivers/kvm/kvm.h
>> +++ b/drivers/kvm/kvm.h
>> @@ - 333,6 +333,7 @@ struct kvm_vcpu_irq {
>>  	int                  deferred;
>>  	struct task_struct  *task;
>>  	int                  guest_mode;
>> +	int                  eventfd;
>>   
> 
> Best to convert the fd to a filp when you install it.  This avoids the
> conversion during runtime and allows you to do error checking earlier.


That was my initial impression also, but then I realized there was a problem with that:  Eventfd doesnt appear to have any way to notify other entities when the fd is closed.  Therefore the filp could be left dangling in this case.  By using the fd instead, I can validate the pointer each time I need it.  Perhaps Davide will have a suggestion here.

Regardless, I do like the idea of checking the fd on assignment.  I will put an eventfd_fget() check into the ioctl too just to catch it early.  I might also add logic to invalidate irq.eventfd if the eventfd_fget() ever fails at runtime because userspace neglects to explicitly unregister (so we don't keep checking an invalid fd over and over).

-Greg

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Re: [PATCH 5/9] KVM: Adds ability to signal userspace using a file-descriptor

[Davide Libenzi]

On Tue, 15 May 2007, Gregory Haskins wrote:

> >>> On Tue, May 15, 2007 at  3:45 AM, in message <4649650E.2070102-atKUWr5tajBWk0Htik3J/w@public.gmane.org>,
> Avi Kivity <avi-atKUWr5tajBWk0Htik3J/w@public.gmane.org> wrote: 
> > Gregory Haskins wrote:
> >> Signed- off- by: Gregory Haskins <ghaskins-Et1tbQHTxzrQT0dZR+AlfA@public.gmane.org>
> >> ---
> >>
> >>  drivers/kvm/kvm.h      |    1 +
> >>  drivers/kvm/kvm_main.c |   52 ++++++++++++++++++++++++++++++++++++++++++------
> >>  include/linux/kvm.h    |    1 +
> >>  3 files changed, 48 insertions(+), 6 deletions(- )
> >>
> >> diff -- git a/drivers/kvm/kvm.h b/drivers/kvm/kvm.h
> >> index 7b5d5e6..f5731c4 100644
> >> ---  a/drivers/kvm/kvm.h
> >> +++ b/drivers/kvm/kvm.h
> >> @@ - 333,6 +333,7 @@ struct kvm_vcpu_irq {
> >>  	int                  deferred;
> >>  	struct task_struct  *task;
> >>  	int                  guest_mode;
> >> +	int                  eventfd;
> >>   
> > 
> > Best to convert the fd to a filp when you install it.  This avoids the
> > conversion during runtime and allows you to do error checking earlier.
> 
> That was my initial impression also, but then I realized there was a 
> problem with that:  Eventfd doesnt appear to have any way to notify 
> other entities when the fd is closed.  Therefore the filp could be left 
> dangling in this case.  By using the fd instead, I can validate the 
> pointer each time I need it.  Perhaps Davide will have a suggestion 
> here.

I don't know how critical is the path where you will be doing check. The 
eventfd_fget() is pretty fast, so if you're not looking at a performance 
critical path, I'd suggest that. Otherwise you can do an early 
eventfd_get, and keep the file*. If you have no the ways to know if the 
userspace disconnected, an atomic_read(&file->f_count)==1 will tell you 
that you're the only owner of the file* (that is, userspace closed the 
eventfd descriptor). I'd give preference to the former option though.
Avi, as you may have read from lkml, Andrew prefers the eventfd symbols 
export to come through the kvm tree, since they do not want to export 
symbols that so far has no module users.


- Davide



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Re: [PATCH 5/9] KVM: Adds ability to signal userspace using a file-descriptor

[Gregory Haskins]

>>> On Tue, May 15, 2007 at 11:40 AM, in message
<Pine.LNX.4.64.0705150832130.30085-GPJ85BhbkB8RepQJljzAVbITYcZ0+W3JAL8bYrjMMd8@public.gmane.org>, Davide Libenzi
<davidel-AhlLAIvw+VEjIGhXcJzhZg@public.gmane.org> wrote: 
>
> I don't know how critical is the path where you will be doing check. The 
> eventfd_fget() is pretty fast, so if you're not looking at a performance 
> critical path, I'd suggest that. Otherwise you can do an early 
> eventfd_get, and keep the file*. If you have no the ways to know if the 
> userspace disconnected, an atomic_read(&file- >f_count)==1 will tell you 
> that you're the only owner of the file* (that is, userspace closed the 
> eventfd descriptor). I'd give preference to the former option though.

Thanks for the insight, Davide.  It sounds like we can probably stay with the way I have it for now, and keep the file->f_count idea in our back pocket should a performance problem arise.

> Avi, as you may have read from lkml, Andrew prefers the eventfd symbols 
> export to come through the kvm tree, since they do not want to export 
> symbols that so far has no module users.

I can create a patch and add it to my series for this work.

Thanks again,
-Greg


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Re: [PATCH 5/9] KVM: Adds ability to signal userspace using a file-descriptor

[Christoph Hellwig]

On Tue, May 15, 2007 at 12:18:17PM -0400, Gregory Haskins wrote:
> >>> On Tue, May 15, 2007 at 11:40 AM, in message
> <Pine.LNX.4.64.0705150832130.30085-GPJ85BhbkB8RepQJljzAVbITYcZ0+W3JAL8bYrjMMd8@public.gmane.org>, Davide Libenzi
> <davidel-AhlLAIvw+VEjIGhXcJzhZg@public.gmane.org> wrote: 
> >
> > I don't know how critical is the path where you will be doing check. The 
> > eventfd_fget() is pretty fast, so if you're not looking at a performance 
> > critical path, I'd suggest that. Otherwise you can do an early 
> > eventfd_get, and keep the file*. If you have no the ways to know if the 
> > userspace disconnected, an atomic_read(&file- >f_count)==1 will tell you 
> > that you're the only owner of the file* (that is, userspace closed the 
> > eventfd descriptor). I'd give preference to the former option though.
> 
> Thanks for the insight, Davide.  It sounds like we can probably stay with the way I have it for now, and keep the file->f_count idea in our back pocket should a performance problem arise.

accessing file->f_count is not allowed for drivers.  It took us quite a
bit of effort to clean up all users a while ago, and it turned out most
of them were rather buggy.


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Re: [PATCH 5/9] KVM: Adds ability to signal userspace using a file-descriptor

[Gregory Haskins]

>>> On Tue, May 15, 2007 at 12:22 PM, in message
<20070515162249.GA19238-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org>, Christoph Hellwig <hch-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org>
wrote: 
> On Tue, May 15, 2007 at 12:18:17PM - 0400, Gregory Haskins wrote:
>> >>> On Tue, May 15, 2007 at 11:40 AM, in message
>> <Pine.LNX.4.64.0705150832130.30085-GPJ85BhbkB8RepQJljzAVbITYcZ0+W3JAL8bYrjMMd8@public.gmane.org>, Davide Libenzi
>> <davidel-AhlLAIvw+VEjIGhXcJzhZg@public.gmane.org> wrote: 
>> >
>> > I don't know how critical is the path where you will be doing check. The 
>> > eventfd_fget() is pretty fast, so if you're not looking at a performance 
>> > critical path, I'd suggest that. Otherwise you can do an early 
>> > eventfd_get, and keep the file*. If you have no the ways to know if the 
>> > userspace disconnected, an atomic_read(&file-  >f_count)==1 will tell you 
>> > that you're the only owner of the file* (that is, userspace closed the 
>> > eventfd descriptor). I'd give preference to the former option though.
>> 
>> Thanks for the insight, Davide.  It sounds like we can probably stay with 
> the way I have it for now, and keep the file- >f_count idea in our back pocket 
> should a performance problem arise.
> 
> accessing file- >f_count is not allowed for drivers.  It took us quite a
> bit of effort to clean up all users a while ago, and it turned out most
> of them were rather buggy.

Ack.

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Re: [PATCH 5/9] KVM: Adds ability to signal userspace using a file-descriptor

[Davide Libenzi]

On Tue, 15 May 2007, Christoph Hellwig wrote:

> On Tue, May 15, 2007 at 12:18:17PM -0400, Gregory Haskins wrote:
> > >>> On Tue, May 15, 2007 at 11:40 AM, in message
> > <Pine.LNX.4.64.0705150832130.30085-GPJ85BhbkB8RepQJljzAVbITYcZ0+W3JAL8bYrjMMd8@public.gmane.org>, Davide Libenzi
> > <davidel-AhlLAIvw+VEjIGhXcJzhZg@public.gmane.org> wrote: 
> > >
> > > I don't know how critical is the path where you will be doing check. The 
> > > eventfd_fget() is pretty fast, so if you're not looking at a performance 
> > > critical path, I'd suggest that. Otherwise you can do an early 
> > > eventfd_get, and keep the file*. If you have no the ways to know if the 
> > > userspace disconnected, an atomic_read(&file- >f_count)==1 will tell you 
> > > that you're the only owner of the file* (that is, userspace closed the 
> > > eventfd descriptor). I'd give preference to the former option though.
> > 
> > Thanks for the insight, Davide.  It sounds like we can probably stay with the way I have it for now, and keep the file->f_count idea in our back pocket should a performance problem arise.
> 
> accessing file->f_count is not allowed for drivers.  It took us quite a
> bit of effort to clean up all users a while ago, and it turned out most
> of them were rather buggy.

Right, you could use the file_count() macro :)
Seriuosly, if this (doing an eventfd_fget+fput) becomes a problem, I can
have the check done in eventfd_signal() and return a proper error code.



- Davide



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Re: [PATCH 5/9] KVM: Adds ability to signal userspace using a file-descriptor

[Avi Kivity]

Davide Libenzi wrote:
> On Tue, 15 May 2007, Christoph Hellwig wrote:
>
>   
>> On Tue, May 15, 2007 at 12:18:17PM -0400, Gregory Haskins wrote:
>>     
>>>>>> On Tue, May 15, 2007 at 11:40 AM, in message
>>>>>>             
>>> <Pine.LNX.4.64.0705150832130.30085-GPJ85BhbkB8RepQJljzAVbITYcZ0+W3JAL8bYrjMMd8@public.gmane.org>, Davide Libenzi
>>> <davidel-AhlLAIvw+VEjIGhXcJzhZg@public.gmane.org> wrote: 
>>>       
>>>> I don't know how critical is the path where you will be doing check. The 
>>>> eventfd_fget() is pretty fast, so if you're not looking at a performance 
>>>> critical path, I'd suggest that. Otherwise you can do an early 
>>>> eventfd_get, and keep the file*. If you have no the ways to know if the 
>>>> userspace disconnected, an atomic_read(&file- >f_count)==1 will tell you 
>>>> that you're the only owner of the file* (that is, userspace closed the 
>>>> eventfd descriptor). I'd give preference to the former option though.
>>>>         
>>> Thanks for the insight, Davide.  It sounds like we can probably stay with the way I have it for now, and keep the file->f_count idea in our back pocket should a performance problem arise.
>>>       
>> accessing file->f_count is not allowed for drivers.  It took us quite a
>> bit of effort to clean up all users a while ago, and it turned out most
>> of them were rather buggy.
>>     
>
> Right, you could use the file_count() macro :)
> Seriuosly, if this (doing an eventfd_fget+fput) becomes a problem, I can
> have the check done in eventfd_signal() and return a proper error code.
>
>   

IMO doing eventfd_fget() asap is best.  I much prefer refcounted 
pointers to handles in the kernel: it's easier to see what things point 
to, and there is to context needed for dereferencing.

-- 
error compiling committee.c: too many arguments to function


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Re: [PATCH 5/9] KVM: Adds ability to signal userspace using a file-descriptor

[Davide Libenzi]

On Wed, 16 May 2007, Avi Kivity wrote:

> IMO doing eventfd_fget() asap is best.  I much prefer refcounted pointers to
> handles in the kernel: it's easier to see what things point to, and there is
> to context needed for dereferencing.

There are concerns (from Al and Christoph) about file lifetime tracking of 
an fd passed down to the kernel.
Avi, how about you go the other way around? I expose you something like:

long eventfd_create(unsigned int count, void (*release)(void *),
                    void *priv);

This returns you an eventfd (or error), and lets you install a callback to 
be used when the file_operations->release is called (basically, userspace 
closed the last file instance).
Can KVM pass back an fd to userspace instead of the other way around?



- Davide



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Re: [PATCH 5/9] KVM: Adds ability to signal userspace using a file-descriptor

[Avi Kivity]

Davide Libenzi wrote:
> On Wed, 16 May 2007, Avi Kivity wrote:
>
>   
>> IMO doing eventfd_fget() asap is best.  I much prefer refcounted pointers to
>> handles in the kernel: it's easier to see what things point to, and there is
>> to context needed for dereferencing.
>>     
>
> There are concerns (from Al and Christoph) about file lifetime tracking of 
> an fd passed down to the kernel.
>   

What concerns are these?

I have my own concerns about bare fds, which can change their backing 
file, and which are dependent on the context.  The kernel appears to be 
moving away from handles to pointers, as seen by the pid -> 
task_struck/struct pid conversion.

> Avi, how about you go the other way around? I expose you something like:
>
> long eventfd_create(unsigned int count, void (*release)(void *),
>                     void *priv);
>
> This returns you an eventfd (or error), and lets you install a callback to 
> be used when the file_operations->release is called (basically, userspace 
> closed the last file instance).
> Can KVM pass back an fd to userspace instead of the other way around?
>   

That was my original thought, but when I saw your proposal I preferred 
that as more flexible.

If we go this way, I prefer to have a struct file * and do away with the 
callback, but that brings us back to the file lifetime concerns.

-- 
error compiling committee.c: too many arguments to function


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Re: [PATCH 5/9] KVM: Adds ability to signal userspace using a file-descriptor

[Davide Libenzi]

On Thu, 17 May 2007, Avi Kivity wrote:

> Davide Libenzi wrote:
> > On Wed, 16 May 2007, Avi Kivity wrote:
> > 
> >   
> > > IMO doing eventfd_fget() asap is best.  I much prefer refcounted pointers
> > > to
> > > handles in the kernel: it's easier to see what things point to, and there
> > > is
> > > to context needed for dereferencing.
> > >     
> > 
> > There are concerns (from Al and Christoph) about file lifetime tracking of
> > an fd passed down to the kernel.
> >   
> 
> What concerns are these?
> 
> I have my own concerns about bare fds, which can change their backing file,
> and which are dependent on the context.  The kernel appears to be moving away
> from handles to pointers, as seen by the pid -> task_struck/struct pid
> conversion.

The concern is that by keeping a reference to the file* you may end up 
with a file that has no more userspace links. Although the file_count()==1 
will tell you that you've the only reference left, this relies on you 
doing the check. I really don't know how this will be used in KVM, so I 
can't really say how well these concerns applies.




> > Avi, how about you go the other way around? I expose you something like:
> > 
> > long eventfd_create(unsigned int count, void (*release)(void *),
> >                     void *priv);
> > 
> > This returns you an eventfd (or error), and lets you install a callback to
> > be used when the file_operations->release is called (basically, userspace
> > closed the last file instance).
> > Can KVM pass back an fd to userspace instead of the other way around?
> >   
> 
> That was my original thought, but when I saw your proposal I preferred that as
> more flexible.
> 
> If we go this way, I prefer to have a struct file * and do away with the
> callback, but that brings us back to the file lifetime concerns.

Doing the above requires some care too. Access to your copy of the file* 
must be protected by a lock (you can sleep from inside the callback, so a 
mutex is fine too). I'll sketch you some code:


/* Defined in linux/eventfd.h */
struct eventfd_relcb {
	struct list_head lnk;
	void (*proc)(struct eventfd_relcb *);
};

/* Your context data */
struct your_ctx {
	whatever_lock your_lock;
	...
	struct eventfd_relcb rcb;
	struct file *evfile;
};

/* Your eventfd release callback */
void rcb_callback(struct eventfd_relcb *rcb) {
	struct your_ctx *c = container_of(rcb, struct your_ctx, rcb);

	whatever_lock_lock(&c->your_lock);
	...
	c->evfile = NULL;
	whatever_lock_unlock(&c->your_lock);
}

/* Your notify userspace function */
void notify_userspace(struct your_ctx *c) {

	whatever_lock_lock(&c->your_lock);
	if (c->evfile != NULL)
		eventfd_signal(c->evfile, 1);
	whatever_lock_unlock(&c->your_lock);
}

/* Your eventfd create/setup function (modulo error checks) */
void setup_eventfd(struct your_ctx *c) {
	int fd;

	c->rcb.proc = rcb_callback;
	fd = eventfd_create(0, &c->rcb);
	c->evfile = eventfd_fget(fd);
	/* Then return fd to userspace in some way */
	...
}



If, by any chance, you need to detach yourself from the eventfd:

void detach_eventfd(struct your_ctx *c) {

	whatever_lock_lock(&c->your_lock);
	if (c->evfile != NULL) {
		eventfd_del_release_cb(c->evfile, &c->rcb);
		/* And, optionally ... */
		eventfd_set_shutdown(c->evfile);
	}
	whatever_lock_unlock(&c->your_lock);
}


The eventfd_set_shutdown() function will make a POLLIN signaled to 
userspace, and a read(2) on the eventfd will return 0 (like peer 
disconnected sockets). Then userspace will know that no more eventfs will 
show up in there.
Tentative patch below (builds, not tested yet).




- Davide



Index: linux-2.6.22-rc1-git1.mod/fs/eventfd.c
===================================================================
--- linux-2.6.22-rc1-git1.mod.orig/fs/eventfd.c	2007-05-16 15:10:26.000000000 -0700
+++ linux-2.6.22-rc1-git1.mod/fs/eventfd.c	2007-05-17 10:53:38.000000000 -0700
@@ -16,9 +16,15 @@
 #include <linux/anon_inodes.h>
 #include <linux/eventfd.h>
 
+#define EVENTFD_FLG_SHUTDOWN	(1 << 0)
+
+#define EVENTFD_FILE(f)		((f)->f_op == &eventfd_fops)
+
 struct eventfd_ctx {
 	spinlock_t lock;
 	wait_queue_head_t wqh;
+	unsigned long flags;
+
 	/*
 	 * Every time that a write(2) is performed on an eventfd, the
 	 * value of the __u64 being written is added to "count" and a
@@ -28,37 +34,72 @@
 	 * issue a wakeup.
 	 */
 	__u64 count;
+
+	/*
+	 * List of callbacks to be invoked when the eventfd file
+	 * in going away.
+	 */
+	struct list_head rcb_list;
 };
 
-/*
- * Adds "n" to the eventfd counter "count". Returns "n" in case of
- * success, or a value lower then "n" in case of coutner overflow.
- * This function is supposed to be called by the kernel in paths
- * that do not allow sleeping. In this function we allow the counter
- * to reach the ULLONG_MAX value, and we signal this as overflow
- * condition by returining a POLLERR to poll(2).
+/**
+ * eventfd_signal - Adds @count to the eventfd counter "count"
+ *
+ * @file:    [in]  Pointer to the eventfd file
+ * @count:   [in]  Value to be added to the eventfd counter
+ *
+ * Returns @count in case of success, or a value lower then @count in case of
+ * coutner overflow. In this function we allow the counter to reach the
+ * ULLONG_MAX value, and we signal this as overflow condition by returining
+ * a POLLERR to poll(2). This function can be called from any context.
  */
-int eventfd_signal(struct file *file, int n)
+int eventfd_signal(struct file *file, int count)
 {
 	struct eventfd_ctx *ctx = file->private_data;
 	unsigned long flags;
 
-	if (n < 0)
+	if (count < 0)
 		return -EINVAL;
 	spin_lock_irqsave(&ctx->lock, flags);
-	if (ULLONG_MAX - ctx->count < n)
-		n = (int) (ULLONG_MAX - ctx->count);
-	ctx->count += n;
+	if (ULLONG_MAX - ctx->count < count)
+		count = (int) (ULLONG_MAX - ctx->count);
+	ctx->count += count;
 	if (waitqueue_active(&ctx->wqh))
 		wake_up_locked(&ctx->wqh);
 	spin_unlock_irqrestore(&ctx->lock, flags);
 
-	return n;
+	return count;
 }
 
 static int eventfd_release(struct inode *inode, struct file *file)
 {
-	kfree(file->private_data);
+	struct eventfd_ctx *ctx = file->private_data;
+	unsigned long flags;
+	struct eventfd_relcb *rcb;
+
+next:
+	spin_lock_irqsave(&ctx->lock, flags);
+	if (!list_empty(&ctx->rcb_list)) {
+		rcb = list_first_entry(&ctx->rcb_list, struct eventfd_relcb, lnk);
+		list_del_init(&rcb->lnk);
+		spin_unlock_irqrestore(&ctx->lock, flags);
+
+		/*
+		 * We need to call the callback w/out the lock being held.
+		 * When the eventfd kernel user calls us, it is probably holding
+		 * its own lock, and then we lock ctx->lock to operate with our
+		 * data. Here we would be calling the callback with our lock held,
+		 * and the kernel user might be trying to grab its own lock from
+		 * inside the callback. So we would end up with a nice AB-BA
+		 * deadlock.
+		 */
+		(*rcb->proc)(rcb);
+
+		goto next;
+	}
+	spin_unlock_irqrestore(&ctx->lock, flags);
+
+	kfree(ctx);
 	return 0;
 }
 
@@ -73,7 +114,9 @@
 	spin_lock_irqsave(&ctx->lock, flags);
 	if (ctx->count > 0)
 		events |= POLLIN;
-	if (ctx->count == ULLONG_MAX)
+	if (unlikely(ctx->flags & EVENTFD_FLG_SHUTDOWN))
+		events |= POLLIN;
+	if (unlikely(ctx->count == ULLONG_MAX))
 		events |= POLLERR;
 	if (ULLONG_MAX - 1 > ctx->count)
 		events |= POLLOUT;
@@ -86,13 +129,15 @@
 			    loff_t *ppos)
 {
 	struct eventfd_ctx *ctx = file->private_data;
-	ssize_t res;
+	ssize_t res = 0;
 	__u64 ucnt;
 	DECLARE_WAITQUEUE(wait, current);
 
 	if (count < sizeof(ucnt))
 		return -EINVAL;
 	spin_lock_irq(&ctx->lock);
+	if (unlikely(ctx->flags & EVENTFD_FLG_SHUTDOWN))
+		goto out_unlock;
 	res = -EAGAIN;
 	ucnt = ctx->count;
 	if (ucnt > 0)
@@ -122,6 +167,7 @@
 		if (waitqueue_active(&ctx->wqh))
 			wake_up_locked(&ctx->wqh);
 	}
+out_unlock:
 	spin_unlock_irq(&ctx->lock);
 	if (res > 0 && put_user(ucnt, (__u64 __user *) buf))
 		return -EFAULT;
@@ -183,6 +229,15 @@
 	.write		= eventfd_write,
 };
 
+/**
+ * eventfd_fget - Gets a reference of an eventfd file from an eventfd
+ *                file descriptor
+ *
+ * @fd:   [in]   Eventfd file descriptor
+ *
+ * Returns the eventfd file pointer, or error in case the passed file
+ * descriptor is not a valid eventfd file.
+ */
 struct file *eventfd_fget(int fd)
 {
 	struct file *file;
@@ -190,7 +245,7 @@
 	file = fget(fd);
 	if (!file)
 		return ERR_PTR(-EBADF);
-	if (file->f_op != &eventfd_fops) {
+	if (!EVENTFD_FILE(file)) {
 		fput(file);
 		return ERR_PTR(-EINVAL);
 	}
@@ -198,7 +253,95 @@
 	return file;
 }
 
-asmlinkage long sys_eventfd(unsigned int count)
+/**
+ * eventfd_set_shutdown - Sets the shutdown flag in the eventfd, so that the
+ *                        userspace can notice it with a POLLIN from poll(2)
+ *                        and a zero bytes read(2)
+ *
+ * @file:   [in]   Pointer to the eventfd file
+ *
+ * Returns zero in case of success, or -EINVAL if the @file is not an eventfd
+ * file pointer. This function can be called from any context.
+ */
+int eventfd_set_shutdown(struct file *file)
+{
+	struct eventfd_ctx *ctx = file->private_data;
+	unsigned long flags;
+
+	if (unlikely(!EVENTFD_FILE(file)))
+		return -EINVAL;
+	spin_lock_irqsave(&ctx->lock, flags);
+	ctx->flags |= EVENTFD_FLG_SHUTDOWN;
+	if (waitqueue_active(&ctx->wqh))
+		wake_up_locked(&ctx->wqh);
+	spin_unlock_irqrestore(&ctx->lock, flags);
+
+	return 0;
+}
+
+/**
+ * eventfd_add_release_cb - Install a callback function to be invoked when
+ *                          the file_operations->release function is called
+ *                          (that is, right before the eventfd file is going away)
+ *
+ * @file:   [in]   Pointer to the eventfd file
+ * @rcb:    [in]   Pointer to the callabck structure
+ *
+ * Returns zero in case of success, or -EINVAL if the @file is not an eventfd
+ * file pointer. This function can be called from any context.
+ */
+int eventfd_add_release_cb(struct file *file, struct eventfd_relcb *rcb)
+{
+	struct eventfd_ctx *ctx = file->private_data;
+	unsigned long flags;
+
+	if (unlikely(!EVENTFD_FILE(file)))
+		return -EINVAL;
+	spin_lock_irqsave(&ctx->lock, flags);
+	list_add_tail(&rcb->lnk, &ctx->rcb_list);
+	spin_unlock_irqrestore(&ctx->lock, flags);
+
+	return 0;
+}
+
+/**
+ * eventfd_del_release_cb - Deletes a previously installed callback function
+ *                          from the eventfd release callback list
+ *
+ * @file:   [in]   Pointer to the eventfd file
+ * @rcb:    [in]   Pointer to the callabck structure
+ *
+ * Returns zero in case of success, or -EINVAL if the @file is not an eventfd
+ * file pointer. This function can be called from any context.
+ */
+int eventfd_del_release_cb(struct file *file, struct eventfd_relcb *rcb)
+{
+	struct eventfd_ctx *ctx = file->private_data;
+	unsigned long flags;
+
+	if (unlikely(!EVENTFD_FILE(file)))
+		return -EINVAL;
+	spin_lock_irqsave(&ctx->lock, flags);
+	list_del_init(&rcb->lnk);
+	spin_unlock_irqrestore(&ctx->lock, flags);
+
+	return 0;
+}
+
+/**
+ * eventfd_create - Creates an eventfd file and returns its descriptor.
+ *                  It also allows the caller to specify a callback
+ *                  (struct eventfd_relcb) to be invoked when the last
+ *                  instance of this eventfd file goes away. If @rcb is
+ *                  NULL, no callback will be installed
+ *
+ * @count:  [in]   Initial count for the eventfd
+ * @rcb:    [in]   Pointer to the callabck structure, or NULL
+ *
+ * Returns the newly created eventfd file descriptor, or a negative value
+ * in case of error.
+ */
+int eventfd_create(unsigned int count, struct eventfd_relcb *rcb)
 {
 	int error, fd;
 	struct eventfd_ctx *ctx;
@@ -212,6 +355,10 @@
 	init_waitqueue_head(&ctx->wqh);
 	spin_lock_init(&ctx->lock);
 	ctx->count = count;
+	ctx->flags = 0;
+	INIT_LIST_HEAD(&ctx->rcb_list);
+	if (rcb)
+		list_add_tail(&rcb->lnk, &ctx->rcb_list);
 
 	/*
 	 * When we call this, the initialization must be complete, since
@@ -226,3 +373,8 @@
 	return error;
 }
 
+asmlinkage long sys_eventfd(unsigned int count)
+{
+	return eventfd_create(count, NULL);
+}
+
Index: linux-2.6.22-rc1-git1.mod/include/linux/eventfd.h
===================================================================
--- linux-2.6.22-rc1-git1.mod.orig/include/linux/eventfd.h	2007-05-16 15:10:34.000000000 -0700
+++ linux-2.6.22-rc1-git1.mod/include/linux/eventfd.h	2007-05-17 10:48:11.000000000 -0700
@@ -11,15 +11,50 @@
 
 #ifdef __KERNEL__
 
+#include <linux/list.h>
+
+struct eventfd_relcb {
+	struct list_head lnk;
+	void (*proc)(struct eventfd_relcb *);
+};
+
 #ifdef CONFIG_EVENTFD
 
 struct file *eventfd_fget(int fd);
-int eventfd_signal(struct file *file, int n);
+int eventfd_signal(struct file *file, int count);
+int eventfd_add_release_cb(struct file *file, struct eventfd_relcb *rcb);
+int eventfd_del_release_cb(struct file *file, struct eventfd_relcb *rcb);
+int eventfd_set_shutdown(struct file *file);
+int eventfd_create(unsigned int count, struct eventfd_relcb *rcb);
 
 #else /* CONFIG_EVENTFD */
 
-#define eventfd_fget(fd) ERR_PTR(-ENOSYS)
-#define eventfd_signal(f, n) 0
+static inline struct file *eventfd_fget(int fd)
+{
+	return ERR_PTR(-ENOSYS);
+}
+static inline int eventfd_signal(struct file *file, int count)
+{
+	return 0;
+}
+static inline int eventfd_add_release_cb(struct file *file,
+					 struct eventfd_relcb *rcb)
+{
+	return -ENOSYS;
+}
+static inline int eventfd_del_release_cb(struct file *file,
+					 struct eventfd_relcb *rcb)
+{
+	return -ENOSYS;
+}
+static inline int eventfd_set_shutdown(struct file *file)
+{
+	return -ENOSYS;
+}
+static inline int eventfd_create(unsigned int count, struct eventfd_relcb *rcb)
+{
+	return -ENOSYS;
+}
 
 #endif /* CONFIG_EVENTFD */
 

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Re: [PATCH 5/9] KVM: Adds ability to signal userspace using a file-descriptor

[Davide Libenzi]

On Thu, 17 May 2007, Davide Libenzi wrote:

> /* Your eventfd create/setup function (modulo error checks) */
> void setup_eventfd(struct your_ctx *c) {
> 	int fd;
> 
> 	c->rcb.proc = rcb_callback;
> 	fd = eventfd_create(0, &c->rcb);
> 	c->evfile = eventfd_fget(fd);

+	fput(c->evfile);

> 	/* Then return fd to userspace in some way */
> 	...
> }

You need an fput() there, to bring f_count back to 1, of course ;)


- Davide



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Re: [PATCH 5/9] KVM: Adds ability to signal userspace using a file-descriptor

[Avi Kivity]

Davide Libenzi wrote:
> On Thu, 17 May 2007, Avi Kivity wrote:
>
>   
>> Davide Libenzi wrote:
>>     
>>> On Wed, 16 May 2007, Avi Kivity wrote:
>>>
>>>   
>>>       
>>>> IMO doing eventfd_fget() asap is best.  I much prefer refcounted pointers
>>>> to
>>>> handles in the kernel: it's easier to see what things point to, and there
>>>> is
>>>> to context needed for dereferencing.
>>>>     
>>>>         
>>> There are concerns (from Al and Christoph) about file lifetime tracking of
>>> an fd passed down to the kernel.
>>>   
>>>       
>> What concerns are these?
>>
>> I have my own concerns about bare fds, which can change their backing file,
>> and which are dependent on the context.  The kernel appears to be moving away
>> from handles to pointers, as seen by the pid -> task_struck/struct pid
>> conversion.
>>     
>
> The concern is that by keeping a reference to the file* you may end up 
> with a file that has no more userspace links. Although the file_count()==1 
> will tell you that you've the only reference left, this relies on you 
> doing the check. I really don't know how this will be used in KVM, so I 
> can't really say how well these concerns applies.
>
>   

That's perfectly fine for kvm (and as far as I can see, any other 
application: the user losing their eventfd reference is equivalent to 
the user ignoring any events, which should be survivable by the kernel).

>
>
>   
>>> Avi, how about you go the other way around? I expose you something like:
>>>
>>> long eventfd_create(unsigned int count, void (*release)(void *),
>>>                     void *priv);
>>>
>>> This returns you an eventfd (or error), and lets you install a callback to
>>> be used when the file_operations->release is called (basically, userspace
>>> closed the last file instance).
>>> Can KVM pass back an fd to userspace instead of the other way around?
>>>   
>>>       
>> That was my original thought, but when I saw your proposal I preferred that as
>> more flexible.
>>
>> If we go this way, I prefer to have a struct file * and do away with the
>> callback, but that brings us back to the file lifetime concerns.
>>     
>
> Doing the above requires some care too. Access to your copy of the file* 
> must be protected by a lock (you can sleep from inside the callback, so a 
> mutex is fine too). I'll sketch you some code:
>
>
> /* Defined in linux/eventfd.h */
> struct eventfd_relcb {
> 	struct list_head lnk;
> 	void (*proc)(struct eventfd_relcb *);
> };
>
> /* Your context data */
> struct your_ctx {
> 	whatever_lock your_lock;
> 	...
> 	struct eventfd_relcb rcb;
> 	struct file *evfile;
> };
>
> /* Your eventfd release callback */
> void rcb_callback(struct eventfd_relcb *rcb) {
> 	struct your_ctx *c = container_of(rcb, struct your_ctx, rcb);
>
> 	whatever_lock_lock(&c->your_lock);
> 	...
> 	c->evfile = NULL;
> 	whatever_lock_unlock(&c->your_lock);
> }
>
> /* Your notify userspace function */
> void notify_userspace(struct your_ctx *c) {
>
> 	whatever_lock_lock(&c->your_lock);
> 	if (c->evfile != NULL)
> 		eventfd_signal(c->evfile, 1);
> 	whatever_lock_unlock(&c->your_lock);
> }
>
> /* Your eventfd create/setup function (modulo error checks) */
> void setup_eventfd(struct your_ctx *c) {
> 	int fd;
>
> 	c->rcb.proc = rcb_callback;
> 	fd = eventfd_create(0, &c->rcb);
> 	c->evfile = eventfd_fget(fd);
> 	/* Then return fd to userspace in some way */
> 	...
> }
>
>
>
> If, by any chance, you need to detach yourself from the eventfd:
>
> void detach_eventfd(struct your_ctx *c) {
>
> 	whatever_lock_lock(&c->your_lock);
> 	if (c->evfile != NULL) {
> 		eventfd_del_release_cb(c->evfile, &c->rcb);
> 		/* And, optionally ... */
> 		eventfd_set_shutdown(c->evfile);
> 	}
> 	whatever_lock_unlock(&c->your_lock);
> }
>
>
> The eventfd_set_shutdown() function will make a POLLIN signaled to 
> userspace, and a read(2) on the eventfd will return 0 (like peer 
> disconnected sockets). Then userspace will know that no more eventfs will 
> show up in there.
> Tentative patch below (builds, not tested yet).
>
>
>   

Looks like a lot of code for what was supposed to be a code reduction... 
I think I'll look at Gregory's notification-free suggestion instead.


-- 
error compiling committee.c: too many arguments to function


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Re: [PATCH 5/9] KVM: Adds ability to signal userspace using a file-descriptor

[Avi Kivity]

Davide Libenzi wrote:
> On Tue, 15 May 2007, Gregory Haskins wrote:
>
>   
>>>>> On Tue, May 15, 2007 at  3:45 AM, in message <4649650E.2070102-atKUWr5tajBWk0Htik3J/w@public.gmane.org>,
>>>>>           
>> Avi Kivity <avi-atKUWr5tajBWk0Htik3J/w@public.gmane.org> wrote: 
>>     
>>> Gregory Haskins wrote:
>>>       
>>>> Signed- off- by: Gregory Haskins <ghaskins-Et1tbQHTxzrQT0dZR+AlfA@public.gmane.org>
>>>> ---
>>>>
>>>>  drivers/kvm/kvm.h      |    1 +
>>>>  drivers/kvm/kvm_main.c |   52 ++++++++++++++++++++++++++++++++++++++++++------
>>>>  include/linux/kvm.h    |    1 +
>>>>  3 files changed, 48 insertions(+), 6 deletions(- )
>>>>
>>>> diff -- git a/drivers/kvm/kvm.h b/drivers/kvm/kvm.h
>>>> index 7b5d5e6..f5731c4 100644
>>>> ---  a/drivers/kvm/kvm.h
>>>> +++ b/drivers/kvm/kvm.h
>>>> @@ - 333,6 +333,7 @@ struct kvm_vcpu_irq {
>>>>  	int                  deferred;
>>>>  	struct task_struct  *task;
>>>>  	int                  guest_mode;
>>>> +	int                  eventfd;
>>>>   
>>>>         
>>> Best to convert the fd to a filp when you install it.  This avoids the
>>> conversion during runtime and allows you to do error checking earlier.
>>>       
>> That was my initial impression also, but then I realized there was a 
>> problem with that:  Eventfd doesnt appear to have any way to notify 
>> other entities when the fd is closed.  Therefore the filp could be left 
>> dangling in this case.  By using the fd instead, I can validate the 
>> pointer each time I need it.  Perhaps Davide will have a suggestion 
>> here.
>>     
>
> I don't know how critical is the path where you will be doing check. The 
> eventfd_fget() is pretty fast, so if you're not looking at a performance 
> critical path, I'd suggest that. Otherwise you can do an early 
> eventfd_get, and keep the file*. If you have no the ways to know if the 
> userspace disconnected, an atomic_read(&file->f_count)==1 will tell you 
> that you're the only owner of the file* (that is, userspace closed the 
> eventfd descriptor). I'd give preference to the former option though.
>   

We aren't really interested whether userspace is looking or not.  After 
all, it installed the eventfd, so it must be interested in the events.

> Avi, as you may have read from lkml, Andrew prefers the eventfd symbols 
> export to come through the kvm tree, since they do not want to export 
> symbols that so far has no module users.
>
>   

Yes, I'll pick up the patch from lkml.


-- 
error compiling committee.c: too many arguments to function


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Re: [PATCH 5/9] KVM: Adds ability to signal userspace using a file-descriptor

[Avi Kivity]

Gregory Haskins wrote:
>>>> On Tue, May 15, 2007 at  3:45 AM, in message <4649650E.2070102-atKUWr5tajBWk0Htik3J/w@public.gmane.org>,
>>>>         
> Avi Kivity <avi-atKUWr5tajBWk0Htik3J/w@public.gmane.org> wrote: 
>   
>> Gregory Haskins wrote:
>>     
>>> Signed- off- by: Gregory Haskins <ghaskins-Et1tbQHTxzrQT0dZR+AlfA@public.gmane.org>
>>> ---
>>>
>>>  drivers/kvm/kvm.h      |    1 +
>>>  drivers/kvm/kvm_main.c |   52 ++++++++++++++++++++++++++++++++++++++++++------
>>>  include/linux/kvm.h    |    1 +
>>>  3 files changed, 48 insertions(+), 6 deletions(- )
>>>
>>> diff -- git a/drivers/kvm/kvm.h b/drivers/kvm/kvm.h
>>> index 7b5d5e6..f5731c4 100644
>>> ---  a/drivers/kvm/kvm.h
>>> +++ b/drivers/kvm/kvm.h
>>> @@ - 333,6 +333,7 @@ struct kvm_vcpu_irq {
>>>  	int                  deferred;
>>>  	struct task_struct  *task;
>>>  	int                  guest_mode;
>>> +	int                  eventfd;
>>>   
>>>       
>> Best to convert the fd to a filp when you install it.  This avoids the
>> conversion during runtime and allows you to do error checking earlier.
>>     
>
>
> That was my initial impression also, but then I realized there was a problem with that:  Eventfd doesnt appear to have any way to notify other entities when the fd is closed.  Therefore the filp could be left dangling in this case.  By using the fd instead, I can validate the pointer each time I need it.  Perhaps Davide will have a suggestion here.
>   

eventfd_fget() will bump the reference count.

-- 
error compiling committee.c: too many arguments to function


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[PATCH 0/9] in-kernel APIC v2

[Gregory Haskins]

This release fixes two critical issues:

1) Performance was bad in previous versions (QEMU would stay at 80% + even
   when the guest was idle).  Root cause was a latent KVM bug that was not
   exposed with the original interrupt model.  Namely, interrupts were not
   checked during light-exit (see Patch #2).  The behavior we were seeing was
   caused by the system continuously halting, only to determine that there
   were interrupts pending and executing a light-exit.  However, the
   interrupts were never injected so the guest would just tight loop on HLT.

2) Fixed corruption issue were signal reception in the new interrupt code
   could cause us to return to userspace without restoring the host state
   properly.

Regards,
-Greg

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[PATCH 5/9] KVM: Adds ability to signal userspace using a file-descriptor

[Gregory Haskins]

Signed-off-by: Gregory Haskins <ghaskins-Et1tbQHTxzrQT0dZR+AlfA@public.gmane.org>
---

 drivers/kvm/kvm.h      |    2 +
 drivers/kvm/kvm_main.c |   82 ++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 84 insertions(+), 0 deletions(-)

diff --git a/drivers/kvm/kvm.h b/drivers/kvm/kvm.h
index 0f6cc32..b5bfc91 100644
--- a/drivers/kvm/kvm.h
+++ b/drivers/kvm/kvm.h
@@ -331,6 +331,8 @@ struct kvm_vcpu_irq {
 	int                  deferred;
 	struct task_struct  *task;
 	int                  guest_mode;
+	wait_queue_head_t    wq;
+	int                  usignal;
 };
 
 struct kvm_vcpu {
diff --git a/drivers/kvm/kvm_main.c b/drivers/kvm/kvm_main.c
index a160638..6b40c18 100644
--- a/drivers/kvm/kvm_main.c
+++ b/drivers/kvm/kvm_main.c
@@ -40,6 +40,7 @@
 #include <linux/file.h>
 #include <linux/fs.h>
 #include <linux/mount.h>
+#include <linux/poll.h>
 
 #include "x86_emulate.h"
 #include "segment_descriptor.h"
@@ -304,6 +305,7 @@ static struct kvm *kvm_create_vm(void)
 		memset(&vcpu->irq, 0, sizeof(vcpu->irq));
 		spin_lock_init(&vcpu->irq.lock);
 		vcpu->irq.deferred = -1;
+		init_waitqueue_head(&vcpu->irq.wq);
 
 		vcpu->cpu = -1;
 		vcpu->kvm = kvm;
@@ -2265,11 +2267,78 @@ static int kvm_vcpu_release(struct inode *inode, struct file *filp)
 	return 0;
 }
 
+static unsigned int kvm_vcpu_poll(struct file *filp, poll_table *wait)
+{
+	struct kvm_vcpu *vcpu = filp->private_data;
+	unsigned int events = 0;
+	unsigned long flags;
+
+	poll_wait(filp, &vcpu->irq.wq, wait);
+
+	spin_lock_irqsave(&vcpu->irq.lock, flags);
+	if (vcpu->irq.usignal)
+		events |= POLLIN;
+	spin_unlock_irqrestore(&vcpu->irq.lock, flags);
+
+	return events;
+}
+
+static ssize_t kvm_vcpu_read(struct file *filp, char __user *buf, size_t count,
+			     loff_t *ppos)
+{
+	struct kvm_vcpu *vcpu = filp->private_data;
+	ssize_t res = -EAGAIN;
+	DECLARE_WAITQUEUE(wait, current);
+	unsigned long flags;
+	int val;
+
+	if (count < sizeof(vcpu->irq.usignal))
+		return -EINVAL;
+
+	spin_lock_irqsave(&vcpu->irq.lock, flags);
+
+	val = vcpu->irq.usignal;
+
+	if (val > 0)
+		res = sizeof(val);
+	else if (!(filp->f_flags & O_NONBLOCK)) {
+		__add_wait_queue(&vcpu->irq.wq, &wait);
+		for (res = 0;;) {
+			set_current_state(TASK_INTERRUPTIBLE);
+			if (val > 0) {
+				res = sizeof(val);
+				break;
+			}
+			if (signal_pending(current)) {
+				res = -ERESTARTSYS;
+				break;
+			}
+			spin_unlock_irqrestore(&vcpu->irq.lock, flags);
+			schedule();
+			spin_lock_irqsave(&vcpu->irq.lock, flags);
+		}
+		__remove_wait_queue(&vcpu->irq.wq, &wait);
+		__set_current_state(TASK_RUNNING);
+	}
+
+	if (res > 0)
+		vcpu->irq.usignal = 0;
+
+	spin_unlock_irqrestore(&vcpu->irq.lock, flags);
+
+	if (res > 0 && put_user(val, (int __user *) buf))
+		return -EFAULT;
+
+	return res;
+}
+
 static struct file_operations kvm_vcpu_fops = {
 	.release        = kvm_vcpu_release,
 	.unlocked_ioctl = kvm_vcpu_ioctl,
 	.compat_ioctl   = kvm_vcpu_ioctl,
 	.mmap           = kvm_vcpu_mmap,
+	.poll           = kvm_vcpu_poll,
+	.read           = kvm_vcpu_read,
 };
 
 /*
@@ -2336,6 +2405,7 @@ static void kvm_vcpu_intr(struct kvm_irqsink *this,
 	struct kvm_vcpu *vcpu = (struct kvm_vcpu*)this->private;
 	unsigned long flags;
 	int direct_ipi = -1;
+	int indirect_sig = 0;
 
 	spin_lock_irqsave(&vcpu->irq.lock, flags);
 
@@ -2357,6 +2427,15 @@ static void kvm_vcpu_intr(struct kvm_irqsink *this,
 				 */
 				direct_ipi = task_cpu(vcpu->irq.task);
 				BUG_ON(direct_ipi == smp_processor_id());
+			} else {
+				/*
+				 * otherwise, we must assume that we could be
+				 * blocked anywhere, including userspace. Send
+				 * a signal to give everyone a chance to get
+				 * notification
+				 */
+				vcpu->irq.usignal++;
+				indirect_sig = 1;
 			}
 		}
 	}
@@ -2379,6 +2458,9 @@ static void kvm_vcpu_intr(struct kvm_irqsink *this,
 		smp_call_function_single(direct_ipi,
 					 kvm_vcpu_guest_intr,
 					 vcpu, 0, 0);
+
+	if (indirect_sig && waitqueue_active(&vcpu->irq.wq))
+		wake_up(&vcpu->irq.wq);
 }
 
 static void kvm_vcpu_irqsink_init(struct kvm_vcpu *vcpu)


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