[PATCH v3 19/19] arm/arm64: KVM: allow userland to request a virtual GICv3

[Andre Przywara]

With everything in place we allow userland to request the kernel
using a virtual GICv3 in the guest, which finally lifts the 8 vCPU
limit for a guest.
Also we provide the necessary support for guests setting the memory
addresses for the virtual distributor and redistributors.
This requires some userland code to make use of that feature and
explicitly ask for a virtual GICv3.

Signed-off-by: Andre Przywara <andre.przywara at arm.com>
---
 arch/arm64/include/uapi/asm/kvm.h |    7 ++++++
 include/kvm/arm_vgic.h            |    4 ++--
 virt/kvm/arm/vgic-v3-emul.c       |    3 +++
 virt/kvm/arm/vgic.c               |   46 ++++++++++++++++++++++++++-----------
 4 files changed, 45 insertions(+), 15 deletions(-)

diff --git a/arch/arm64/include/uapi/asm/kvm.h b/arch/arm64/include/uapi/asm/kvm.h
index 8e38878..2ed873a 100644
--- a/arch/arm64/include/uapi/asm/kvm.h
+++ b/arch/arm64/include/uapi/asm/kvm.h
@@ -78,6 +78,13 @@ struct kvm_regs {
 #define KVM_VGIC_V2_DIST_SIZE		0x1000
 #define KVM_VGIC_V2_CPU_SIZE		0x2000
 
+/* Supported VGICv3 address types  */
+#define KVM_VGIC_V3_ADDR_TYPE_DIST	2
+#define KVM_VGIC_V3_ADDR_TYPE_REDIST	3
+
+#define KVM_VGIC_V3_DIST_SIZE		SZ_64K
+#define KVM_VGIC_V3_REDIST_SIZE		(2 * SZ_64K)
+
 #define KVM_ARM_VCPU_POWER_OFF		0 /* CPU is started in OFF state */
 #define KVM_ARM_VCPU_EL1_32BIT		1 /* CPU running a 32bit VM */
 #define KVM_ARM_VCPU_PSCI_0_2		2 /* CPU uses PSCI v0.2 */
diff --git a/include/kvm/arm_vgic.h b/include/kvm/arm_vgic.h
index c303083..e2e432c 100644
--- a/include/kvm/arm_vgic.h
+++ b/include/kvm/arm_vgic.h
@@ -35,8 +35,8 @@
 #define VGIC_MAX_IRQS		1024
 
 /* Sanity checks... */
-#if (KVM_MAX_VCPUS > 8)
-#error	Invalid number of CPU interfaces
+#if (KVM_MAX_VCPUS > 255)
+#error Too many KVM VCPUs, the VGIC only supports up to 255 VCPUs for now
 #endif
 
 #if (VGIC_NR_IRQS_LEGACY & 31)
diff --git a/virt/kvm/arm/vgic-v3-emul.c b/virt/kvm/arm/vgic-v3-emul.c
index bcb5374..ba6b0b5 100644
--- a/virt/kvm/arm/vgic-v3-emul.c
+++ b/virt/kvm/arm/vgic-v3-emul.c
@@ -870,6 +870,9 @@ static int vgic_v3_has_attr(struct kvm_device *dev,
 		case KVM_VGIC_V2_ADDR_TYPE_DIST:
 		case KVM_VGIC_V2_ADDR_TYPE_CPU:
 			return -ENXIO;
+		case KVM_VGIC_V3_ADDR_TYPE_DIST:
+		case KVM_VGIC_V3_ADDR_TYPE_REDIST:
+			return 0;
 		}
 		break;
 	case KVM_DEV_ARM_VGIC_GRP_DIST_REGS:
diff --git a/virt/kvm/arm/vgic.c b/virt/kvm/arm/vgic.c
index 16d7c9d..a5abef1 100644
--- a/virt/kvm/arm/vgic.c
+++ b/virt/kvm/arm/vgic.c
@@ -1647,7 +1647,7 @@ static int vgic_ioaddr_assign(struct kvm *kvm, phys_addr_t *ioaddr,
 /**
  * kvm_vgic_addr - set or get vgic VM base addresses
  * @kvm:   pointer to the vm struct
- * @type:  the VGIC addr type, one of KVM_VGIC_V2_ADDR_TYPE_XXX
+ * @type:  the VGIC addr type, one of KVM_VGIC_V[23]_ADDR_TYPE_XXX
  * @addr:  pointer to address value
  * @write: if true set the address in the VM address space, if false read the
  *          address
@@ -1661,29 +1661,49 @@ int kvm_vgic_addr(struct kvm *kvm, unsigned long type, u64 *addr, bool write)
 {
 	int r = 0;
 	struct vgic_dist *vgic = &kvm->arch.vgic;
+	int type_needed;
+	phys_addr_t *addr_ptr, block_size;
 
 	mutex_lock(&kvm->lock);
 	switch (type) {
 	case KVM_VGIC_V2_ADDR_TYPE_DIST:
-		if (write) {
-			r = vgic_ioaddr_assign(kvm, &vgic->vgic_dist_base,
-					       *addr, KVM_VGIC_V2_DIST_SIZE);
-		} else {
-			*addr = vgic->vgic_dist_base;
-		}
+		type_needed = KVM_DEV_TYPE_ARM_VGIC_V2;
+		addr_ptr = &vgic->vgic_dist_base;
+		block_size = KVM_VGIC_V2_DIST_SIZE;
 		break;
 	case KVM_VGIC_V2_ADDR_TYPE_CPU:
-		if (write) {
-			r = vgic_ioaddr_assign(kvm, &vgic->vgic_cpu_base,
-					       *addr, KVM_VGIC_V2_CPU_SIZE);
-		} else {
-			*addr = vgic->vgic_cpu_base;
-		}
+		type_needed = KVM_DEV_TYPE_ARM_VGIC_V2;
+		addr_ptr = &vgic->vgic_cpu_base;
+		block_size = KVM_VGIC_V2_CPU_SIZE;
 		break;
+#ifdef CONFIG_ARM_GIC_V3
+	case KVM_VGIC_V3_ADDR_TYPE_DIST:
+		type_needed = KVM_DEV_TYPE_ARM_VGIC_V3;
+		addr_ptr = &vgic->vgic_dist_base;
+		block_size = KVM_VGIC_V3_DIST_SIZE;
+		break;
+	case KVM_VGIC_V3_ADDR_TYPE_REDIST:
+		type_needed = KVM_DEV_TYPE_ARM_VGIC_V3;
+		addr_ptr = &vgic->vgic_redist_base;
+		block_size = KVM_VGIC_V3_REDIST_SIZE;
+		break;
+#endif
 	default:
 		r = -ENODEV;
+		goto out;
+	}
+
+	if (vgic->vgic_model != type_needed) {
+		r = -ENODEV;
+		goto out;
 	}
 
+	if (write)
+		r = vgic_ioaddr_assign(kvm, addr_ptr, *addr, block_size);
+	else
+		*addr = *addr_ptr;
+
+out:
 	mutex_unlock(&kvm->lock);
 	return r;
 }
-- 
1.7.9.5