[PATCH 08/12] KVM: arm/arm64: implement kvm_io_bus MMIO handling for the VGIC

[Andre Przywara <andre.przywara@arm.com>]

Currently we use a lot of VGIC specific code to do the MMIO
dispatching.
Use the previous reworks to add kvm_io_bus style MMIO handlers.

Those are not yet called by the MMIO abort handler, also the actual
VGIC emulator function do not make use of it yet, but will be enabled
with the following patches.

Signed-off-by: Andre Przywara <andre.przywara@arm.com>
---
 include/kvm/arm_vgic.h |    9 ++++
 virt/kvm/arm/vgic.c    |  111 ++++++++++++++++++++++++++++++++++++++++++++++++
 virt/kvm/arm/vgic.h    |    7 +++
 3 files changed, 127 insertions(+)

diff --git a/include/kvm/arm_vgic.h b/include/kvm/arm_vgic.h
index b81630b..4bfc6a3 100644
--- a/include/kvm/arm_vgic.h
+++ b/include/kvm/arm_vgic.h
@@ -24,6 +24,7 @@
 #include <linux/irqreturn.h>
 #include <linux/spinlock.h>
 #include <linux/types.h>
+#include <kvm/iodev.h>
 
 #define VGIC_NR_IRQS_LEGACY	256
 #define VGIC_NR_SGIS		16
@@ -147,6 +148,14 @@ struct vgic_vm_ops {
 	int	(*map_resources)(struct kvm *, const struct vgic_params *);
 };
 
+struct vgic_io_device {
+	gpa_t addr;
+	int len;
+	const struct vgic_io_range *reg_ranges;
+	struct kvm_vcpu *redist_vcpu;
+	struct kvm_io_device dev;
+};
+
 struct vgic_dist {
 	spinlock_t		lock;
 	bool			in_kernel;
diff --git a/virt/kvm/arm/vgic.c b/virt/kvm/arm/vgic.c
index 7aae19b..71389b8 100644
--- a/virt/kvm/arm/vgic.c
+++ b/virt/kvm/arm/vgic.c
@@ -32,6 +32,8 @@
 #include <asm/kvm_arm.h>
 #include <asm/kvm_mmu.h>
 #include <trace/events/kvm.h>
+#include <asm/kvm.h>
+#include <kvm/iodev.h>
 
 /*
  * How the whole thing works (courtesy of Christoffer Dall):
@@ -774,6 +776,66 @@ bool vgic_handle_mmio_range(struct kvm_vcpu *vcpu, struct kvm_run *run,
 }
 
 /**
+ * vgic_handle_mmio_access - handle an in-kernel MMIO access
+ * This is called by the read/write KVM IO device wrappers below.
+ * @vcpu:	pointer to the vcpu performing the access
+ * @this:	pointer to the KVM IO device in charge
+ * @addr:	guest physical address of the access
+ * @len:	size of the access
+ * @val:	pointer to the data region
+ * @is_write:	read or write access
+ *
+ * returns true if the MMIO access could be performed
+ */
+static int vgic_handle_mmio_access(struct kvm_vcpu *vcpu,
+				   struct kvm_io_device *this, gpa_t addr,
+				   int len, void *val, bool is_write)
+{
+	struct vgic_dist *dist = &vcpu->kvm->arch.vgic;
+	struct vgic_io_device *iodev = container_of(this,
+						    struct vgic_io_device, dev);
+	struct kvm_run *run = vcpu->run;
+	const struct vgic_io_range *range;
+	struct kvm_exit_mmio mmio;
+	bool updated_state;
+	gpa_t offset;
+
+	offset = addr - iodev->addr;
+	range = vgic_find_range(iodev->reg_ranges, len, offset);
+	if (unlikely(!range || !range->handle_mmio)) {
+		pr_warn("Unhandled access %d %08llx %d\n", is_write, addr, len);
+		return -ENXIO;
+	}
+
+	mmio.phys_addr = addr;
+	mmio.len = len;
+	mmio.is_write = is_write;
+	if (is_write)
+		memcpy(mmio.data, val, len);
+	mmio.private = iodev->redist_vcpu;
+
+	spin_lock(&dist->lock);
+	offset -= range->base;
+	if (vgic_validate_access(dist, range, offset)) {
+		updated_state = call_range_handler(vcpu, &mmio, offset, range);
+		if (!is_write)
+			memcpy(val, mmio.data, len);
+	} else {
+		if (!is_write)
+			memset(val, 0, len);
+		updated_state = false;
+	}
+	spin_unlock(&dist->lock);
+	kvm_prepare_mmio(run, &mmio);
+	kvm_handle_mmio_return(vcpu, run);
+
+	if (updated_state)
+		vgic_kick_vcpus(vcpu->kvm);
+
+	return 0;
+}
+
+/**
  * vgic_handle_mmio - handle an in-kernel MMIO access for the GIC emulation
  * @vcpu:      pointer to the vcpu performing the access
  * @run:       pointer to the kvm_run structure
@@ -797,6 +859,55 @@ bool vgic_handle_mmio(struct kvm_vcpu *vcpu, struct kvm_run *run,
 	return vcpu->kvm->arch.vgic.vm_ops.handle_mmio(vcpu, run, mmio);
 }
 
+static int vgic_handle_mmio_read(struct kvm_vcpu *vcpu,
+				 struct kvm_io_device *this,
+				 gpa_t addr, int len, void *val)
+{
+	return vgic_handle_mmio_access(vcpu, this, addr, len, val, false);
+}
+
+static int vgic_handle_mmio_write(struct kvm_vcpu *vcpu,
+				  struct kvm_io_device *this,
+				  gpa_t addr, int len, const void *val)
+{
+	return vgic_handle_mmio_access(vcpu, this, addr, len, (void *)val,
+				       true);
+}
+
+struct kvm_io_device_ops vgic_io_ops = {
+	.read	= vgic_handle_mmio_read,
+	.write	= vgic_handle_mmio_write,
+};
+
+int vgic_register_kvm_io_dev(struct kvm *kvm, gpa_t base, int len,
+			     const struct vgic_io_range *ranges,
+			     int redist_id,
+			     struct vgic_io_device *iodev)
+{
+	struct kvm_vcpu *vcpu = NULL;
+	int ret;
+
+	if (redist_id >= 0)
+		vcpu = kvm_get_vcpu(kvm, redist_id);
+
+	iodev->addr		= base;
+	iodev->len		= len;
+	iodev->reg_ranges	= ranges;
+	iodev->redist_vcpu	= vcpu;
+
+	kvm_iodevice_init(&iodev->dev, &vgic_io_ops);
+
+	mutex_lock(&kvm->slots_lock);
+
+	ret = kvm_io_bus_register_dev(kvm, KVM_MMIO_BUS, base, len,
+				      &iodev->dev);
+	mutex_unlock(&kvm->slots_lock);
+	if (ret < 0)
+		return ret;
+
+	return 0;
+}
+
 static int vgic_nr_shared_irqs(struct vgic_dist *dist)
 {
 	return dist->nr_irqs - VGIC_NR_PRIVATE_IRQS;
diff --git a/virt/kvm/arm/vgic.h b/virt/kvm/arm/vgic.h
index ffafb15..f2063a7 100644
--- a/virt/kvm/arm/vgic.h
+++ b/virt/kvm/arm/vgic.h
@@ -20,6 +20,8 @@
 #ifndef __KVM_VGIC_H__
 #define __KVM_VGIC_H__
 
+#include <kvm/iodev.h>
+
 #define VGIC_ADDR_UNDEF		(-1)
 #define IS_VGIC_ADDR_UNDEF(_x)  ((_x) == VGIC_ADDR_UNDEF)
 
@@ -82,6 +84,11 @@ struct vgic_io_range {
 			    phys_addr_t offset);
 };
 
+int vgic_register_kvm_io_dev(struct kvm *kvm, gpa_t base, int len,
+			     const struct vgic_io_range *ranges,
+			     int redist_id,
+			     struct vgic_io_device *iodev);
+
 static inline bool is_in_range(phys_addr_t addr, unsigned long len,
 			       phys_addr_t baseaddr, unsigned long size)
 {
-- 
1.7.9.5