[PATCH v5 05/13] ARM: KVM: Inject IRQs and FIQs from userspace

[Christoffer Dall <c.dall@virtualopensystems.com>]

Userspace can inject IRQs and FIQs through the KVM_IRQ_LINE VM ioctl.
This ioctl is used since the sematics are in fact two lines that can be
either raised or lowered on the VCPU - the IRQ and FIQ lines.

KVM needs to know which VCPU it must operate on and whether the FIQ or
IRQ line is raised/lowered. Hence both pieces of information is packed
in the kvm_irq_level->irq field. The irq fild value will be:
  IRQ: vcpu_index * 2
  FIQ: (vcpu_index * 2) + 1

This is documented in Documentation/kvm/api.txt.

The effect of the ioctl is simply to simply raise/lower the
corresponding virt_irq field on the VCPU struct, which will cause the
world-switch code to raise/lower virtual interrupts when running the
guest on next switch. The wait_for_interrupt flag is also cleared for
raised IRQs causing an idle VCPU to become active again.

Note: The custom trace_kvm_irq_line is used despite a generic definition of
trace_kvm_set_irq, since the trace-Kvm_set_irq depends on the x86-specific
define of __HAVE_IOAPIC. Either the trace event should be created
regardless of this define or it should depend on another ifdef clause,
common for both x86 and ARM. However, since the arguments don't really
match those used in ARM, I am yet to be convinced why this is necessary.

Signed-off-by: Christoffer Dall <c.dall@virtualopensystems.com>
---
 Documentation/virtual/kvm/api.txt |   10 ++++++-
 arch/arm/include/asm/kvm.h        |    8 ++++++
 arch/arm/include/asm/kvm_arm.h    |    1 +
 arch/arm/kvm/arm.c                |   53 ++++++++++++++++++++++++++++++++++++-
 arch/arm/kvm/trace.h              |   21 +++++++++++++++
 include/linux/kvm.h               |    1 +
 6 files changed, 91 insertions(+), 3 deletions(-)

diff --git a/Documentation/virtual/kvm/api.txt b/Documentation/virtual/kvm/api.txt
index 7945b0b..4abaa67 100644
--- a/Documentation/virtual/kvm/api.txt
+++ b/Documentation/virtual/kvm/api.txt
@@ -572,7 +572,7 @@ only go to the IOAPIC.  On ia64, a IOSAPIC is created.
 4.25 KVM_IRQ_LINE
 
 Capability: KVM_CAP_IRQCHIP
-Architectures: x86, ia64
+Architectures: x86, ia64, arm
 Type: vm ioctl
 Parameters: struct kvm_irq_level
 Returns: 0 on success, -1 on error
@@ -582,6 +582,14 @@ Requires that an interrupt controller model has been previously created with
 KVM_CREATE_IRQCHIP.  Note that edge-triggered interrupts require the level
 to be set to 1 and then back to 0.
 
+KVM_CREATE_IRQCHIP (except for ARM).  Note that edge-triggered interrupts
+require the level to be set to 1 and then back to 0.
+
+ARM uses two types of interrupt lines per CPU, ie. IRQ and FIQ. The value of the
+irq field should be (VCPU_INDEX * 2) for IRQs and ((VCPU_INDEX * 2) + 1) for
+FIQs. Level is used to raise/lower the line. See arch/arm/include/asm/kvm.h for
+convenience macros.
+
 struct kvm_irq_level {
 	union {
 		__u32 irq;     /* GSI */
diff --git a/arch/arm/include/asm/kvm.h b/arch/arm/include/asm/kvm.h
index 87dc33b..8935062 100644
--- a/arch/arm/include/asm/kvm.h
+++ b/arch/arm/include/asm/kvm.h
@@ -20,6 +20,14 @@
 #include <asm/types.h>
 
 /*
+ * KVM_IRQ_LINE macros to set/read IRQ/FIQ for specific VCPU index.
+ */
+enum KVM_ARM_IRQ_LINE_TYPE {
+	KVM_ARM_IRQ_LINE = 0,
+	KVM_ARM_FIQ_LINE = 1,
+};
+
+/*
  * Modes used for short-hand mode determinition in the world-switch code and
  * in emulation code.
  *
diff --git a/arch/arm/include/asm/kvm_arm.h b/arch/arm/include/asm/kvm_arm.h
index 835abd1..e378a37 100644
--- a/arch/arm/include/asm/kvm_arm.h
+++ b/arch/arm/include/asm/kvm_arm.h
@@ -49,6 +49,7 @@
 #define HCR_VM		1
 #define HCR_GUEST_MASK (HCR_TSC | HCR_TWE | HCR_TWI | HCR_VM | HCR_AMO | \
 			HCR_AMO | HCR_IMO | HCR_FMO | HCR_SWIO)
+#define HCR_VIRT_EXCP_MASK (HCR_VA | HCR_VI | HCR_VF)
 
 /* Hyp System Control Register (HSCTLR) bits */
 #define HSCTLR_TE	(1 << 30)
diff --git a/arch/arm/kvm/arm.c b/arch/arm/kvm/arm.c
index 89ba18d..fc0bd6b 100644
--- a/arch/arm/kvm/arm.c
+++ b/arch/arm/kvm/arm.c
@@ -299,6 +299,43 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu, struct kvm_run *run)
 	return -EINVAL;
 }
 
+static int kvm_arch_vm_ioctl_irq_line(struct kvm *kvm,
+				      struct kvm_irq_level *irq_level)
+{
+	u32 mask;
+	unsigned int vcpu_idx;
+	struct kvm_vcpu *vcpu;
+
+	vcpu_idx = irq_level->irq / 2;
+	if (vcpu_idx >= KVM_MAX_VCPUS)
+		return -EINVAL;
+
+	vcpu = kvm_get_vcpu(kvm, vcpu_idx);
+	if (!vcpu)
+		return -EINVAL;
+
+	switch (irq_level->irq % 2) {
+	case KVM_ARM_IRQ_LINE:
+		mask = HCR_VI;
+		break;
+	case KVM_ARM_FIQ_LINE:
+		mask = HCR_VF;
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	trace_kvm_irq_line(irq_level->irq % 2, irq_level->level, vcpu_idx);
+
+	if (irq_level->level) {
+		vcpu->arch.virt_irq |= mask;
+		vcpu->arch.wait_for_interrupts = 0;
+	} else
+		vcpu->arch.virt_irq &= ~mask;
+
+	return 0;
+}
+
 long kvm_arch_vcpu_ioctl(struct file *filp,
 			 unsigned int ioctl, unsigned long arg)
 {
@@ -313,8 +350,20 @@ int kvm_vm_ioctl_get_dirty_log(struct kvm *kvm, struct kvm_dirty_log *log)
 long kvm_arch_vm_ioctl(struct file *filp,
 		       unsigned int ioctl, unsigned long arg)
 {
-	printk(KERN_ERR "kvm_arch_vm_ioctl: Unsupported ioctl (%d)\n", ioctl);
-	return -EINVAL;
+	struct kvm *kvm = filp->private_data;
+	void __user *argp = (void __user *)arg;
+
+	switch (ioctl) {
+	case KVM_IRQ_LINE: {
+		struct kvm_irq_level irq_event;
+
+		if (copy_from_user(&irq_event, argp, sizeof irq_event))
+			return -EFAULT;
+		return kvm_arch_vm_ioctl_irq_line(kvm, &irq_event);
+	}
+	default:
+		return -EINVAL;
+	}
 }
 
 /**
diff --git a/arch/arm/kvm/trace.h b/arch/arm/kvm/trace.h
index f8869c1..ac64e3a 100644
--- a/arch/arm/kvm/trace.h
+++ b/arch/arm/kvm/trace.h
@@ -40,6 +40,27 @@ TRACE_EVENT(kvm_exit,
 );
 
 
+TRACE_EVENT(kvm_irq_line,
+	TP_PROTO(unsigned int type, unsigned int level, unsigned int vcpu_idx),
+	TP_ARGS(type, level, vcpu_idx),
+
+	TP_STRUCT__entry(
+		__field(	unsigned int,	type			)
+		__field(	unsigned int,	level			)
+		__field(	unsigned int,	vcpu_idx		)
+	),
+
+	TP_fast_assign(
+		__entry->type			= type;
+		__entry->level			= level;
+		__entry->vcpu_idx		= vcpu_idx;
+	),
+
+	TP_printk("KVM_IRQ_LINE: type: %s, level: %u, vcpu: %u",
+		(__entry->type == KVM_ARM_IRQ_LINE) ? "IRQ" : "FIQ",
+		__entry->level, __entry->vcpu_idx)
+);
+
 
 #endif /* _TRACE_KVM_H */
 
diff --git a/include/linux/kvm.h b/include/linux/kvm.h
index c3892fc..679abbb 100644
--- a/include/linux/kvm.h
+++ b/include/linux/kvm.h
@@ -111,6 +111,7 @@ struct kvm_irq_level {
 	 * ACPI gsi notion of irq.
 	 * For IA-64 (APIC model) IOAPIC0: irq 0-23; IOAPIC1: irq 24-47..
 	 * For X86 (standard AT mode) PIC0/1: irq 0-15. IOAPIC0: 0-23..
+	 * For ARM: IRQ: irq = (2*vcpu_index). FIQ: irq = (2*vcpu_indx + 1).
 	 */
 	union {
 		__u32 irq;