[PATCH v5 18/19] arm/arm64: KVM: enable kernel side of GICv3 emulation

[Andre Przywara]

With all the necessary GICv3 emulation code in place, we can now
connect the code to the GICv3 backend in the kernel.
The LR register handling is different depending on the emulated GIC
model, so provide different implementations for each.
Also allow non-v2-compatible GICv3 implementations (which don't
provide MMIO regions for the virtual CPU interface in the DT), but
restrict those hosts to support GICv3 guests only.

Signed-off-by: Andre Przywara <andre.przywara at arm.com>
---
Changelog v4...v5:
- minor whitespace and comments fixes

Changelog v3...v4:
- handle differences between GICv2-on-v3 and GICv3-on-v3 in existing functions
- remove init_*_emul() functions
- remove max_vcpus setting (done in earlier patches now)
- adapt to new vgic_v<n>_init_emulation behaviour

 virt/kvm/arm/vgic-v3.c |   84 ++++++++++++++++++++++++++++++++----------------
 virt/kvm/arm/vgic.c    |    5 +++
 2 files changed, 61 insertions(+), 28 deletions(-)

diff --git a/virt/kvm/arm/vgic-v3.c b/virt/kvm/arm/vgic-v3.c
index 5249048..88e2ed8 100644
--- a/virt/kvm/arm/vgic-v3.c
+++ b/virt/kvm/arm/vgic-v3.c
@@ -34,6 +34,7 @@
 #define GICH_LR_VIRTUALID		(0x3ffUL << 0)
 #define GICH_LR_PHYSID_CPUID_SHIFT	(10)
 #define GICH_LR_PHYSID_CPUID		(7UL << GICH_LR_PHYSID_CPUID_SHIFT)
+#define ICH_LR_VIRTUALID_MASK		(BIT_ULL(32) - 1)
 
 /*
  * LRs are stored in reverse order in memory. make sure we index them
@@ -48,12 +49,17 @@ static struct vgic_lr vgic_v3_get_lr(const struct kvm_vcpu *vcpu, int lr)
 	struct vgic_lr lr_desc;
 	u64 val = vcpu->arch.vgic_cpu.vgic_v3.vgic_lr[LR_INDEX(lr)];
 
-	lr_desc.irq	= val & GICH_LR_VIRTUALID;
-	if (lr_desc.irq <= 15)
-		lr_desc.source	= (val >> GICH_LR_PHYSID_CPUID_SHIFT) & 0x7;
+	if (vcpu->kvm->arch.vgic.vgic_model == KVM_DEV_TYPE_ARM_VGIC_V3)
+		lr_desc.irq = val & ICH_LR_VIRTUALID_MASK;
 	else
-		lr_desc.source = 0;
-	lr_desc.state	= 0;
+		lr_desc.irq = val & GICH_LR_VIRTUALID;
+
+	lr_desc.source = 0;
+	if (lr_desc.irq <= 15 &&
+	    vcpu->kvm->arch.vgic.vgic_model == KVM_DEV_TYPE_ARM_VGIC_V2)
+		lr_desc.source = (val >> GICH_LR_PHYSID_CPUID_SHIFT) & 0x7;
+
+	lr_desc.state = 0;
 
 	if (val & ICH_LR_PENDING_BIT)
 		lr_desc.state |= LR_STATE_PENDING;
@@ -68,8 +74,20 @@ static struct vgic_lr vgic_v3_get_lr(const struct kvm_vcpu *vcpu, int lr)
 static void vgic_v3_set_lr(struct kvm_vcpu *vcpu, int lr,
 			   struct vgic_lr lr_desc)
 {
-	u64 lr_val = (((u32)lr_desc.source << GICH_LR_PHYSID_CPUID_SHIFT) |
-		      lr_desc.irq);
+	u64 lr_val;
+
+	lr_val = lr_desc.irq;
+
+	/*
+	 * Currently all guest IRQs are Group1, as Group0 would result
+	 * in a FIQ in the guest, which it wouldn't expect.
+	 * Eventually we want to make this configurable, so we may revisit
+	 * this in the future.
+	 */
+	if (vcpu->kvm->arch.vgic.vgic_model == KVM_DEV_TYPE_ARM_VGIC_V3)
+		lr_val |= ICH_LR_GROUP;
+	else
+		lr_val |= (u32)lr_desc.source << GICH_LR_PHYSID_CPUID_SHIFT;
 
 	if (lr_desc.state & LR_STATE_PENDING)
 		lr_val |= ICH_LR_PENDING_BIT;
@@ -154,7 +172,15 @@ static void vgic_v3_enable(struct kvm_vcpu *vcpu)
 	 */
 	vgic_v3->vgic_vmcr = 0;
 
-	vgic_v3->vgic_sre = 0;
+	/*
+	 * If we are emulating a GICv3, we do it in an non-GICv2-compatible
+	 * way, so we force SRE to 1 to demonstrate this to the guest.
+	 * This goes with the spec allowing the value to be RAO/WI.
+	 */
+	if (vcpu->kvm->arch.vgic.vgic_model == KVM_DEV_TYPE_ARM_VGIC_V3)
+		vgic_v3->vgic_sre = ICC_SRE_EL1_SRE;
+	else
+		vgic_v3->vgic_sre = 0;
 
 	/* Get the show on the road... */
 	vgic_v3->vgic_hcr = ICH_HCR_EN;
@@ -215,28 +241,30 @@ int vgic_v3_probe(struct device_node *vgic_node,
 
 	gicv_idx += 3; /* Also skip GICD, GICC, GICH */
 	if (of_address_to_resource(vgic_node, gicv_idx, &vcpu_res)) {
-		kvm_err("Cannot obtain GICV region\n");
-		ret = -ENXIO;
-		goto out;
-	}
-
-	if (!PAGE_ALIGNED(vcpu_res.start)) {
-		kvm_err("GICV physical address 0x%llx not page aligned\n",
-			(unsigned long long)vcpu_res.start);
-		ret = -ENXIO;
-		goto out;
-	}
-
-	if (!PAGE_ALIGNED(resource_size(&vcpu_res))) {
-		kvm_err("GICV size 0x%llx not a multiple of page size 0x%lx\n",
-			(unsigned long long)resource_size(&vcpu_res),
-			PAGE_SIZE);
-		ret = -ENXIO;
-		goto out;
+		kvm_info("GICv3: GICv2 emulation not available\n");
+		vgic->vcpu_base = 0;
+	} else {
+		if (!PAGE_ALIGNED(vcpu_res.start)) {
+			kvm_err("GICV physical address 0x%llx not page aligned\n",
+				(unsigned long long)vcpu_res.start);
+			ret = -ENXIO;
+			goto out;
+		}
+
+		if (!PAGE_ALIGNED(resource_size(&vcpu_res))) {
+			kvm_err("GICV size 0x%llx not a multiple of page size 0x%lx\n",
+				(unsigned long long)resource_size(&vcpu_res),
+				PAGE_SIZE);
+			ret = -ENXIO;
+			goto out;
+		}
+
+		vgic->vcpu_base = vcpu_res.start;
+		kvm_register_device_ops(&kvm_arm_vgic_v2_ops,
+					KVM_DEV_TYPE_ARM_VGIC_V2);
 	}
-	kvm_register_device_ops(&kvm_arm_vgic_v2_ops, KVM_DEV_TYPE_ARM_VGIC_V2);
+	kvm_register_device_ops(&kvm_arm_vgic_v3_ops, KVM_DEV_TYPE_ARM_VGIC_V3);
 
-	vgic->vcpu_base = vcpu_res.start;
 	vgic->vctrl_base = NULL;
 	vgic->type = VGIC_V3;
 	vgic->max_gic_vcpus = KVM_MAX_VCPUS;
diff --git a/virt/kvm/arm/vgic.c b/virt/kvm/arm/vgic.c
index d7d9258..a57d139 100644
--- a/virt/kvm/arm/vgic.c
+++ b/virt/kvm/arm/vgic.c
@@ -1584,6 +1584,11 @@ static int init_vgic_model(struct kvm *kvm, int type)
 	case KVM_DEV_TYPE_ARM_VGIC_V2:
 		ret = vgic_v2_init_emulation(kvm);
 		break;
+#ifdef CONFIG_ARM_GIC_V3
+	case KVM_DEV_TYPE_ARM_VGIC_V3:
+		ret = vgic_v3_init_emulation(kvm);
+		break;
+#endif
 	default:
 		ret = -ENODEV;
 		break;
-- 
1.7.9.5