[RFC PATCH v2 03/38] KVM: arm64: Add KVM nesting feature

[Jintack Lim]

From: Christoffer Dall <christoffer.dall at linaro.org>

Set the initial exception level of the guest to EL2 if nested
virtualization feature is enabled.

Signed-off-by: Christoffer Dall <christoffer.dall at linaro.org>
Signed-off-by: Jintack Lim <jintack at cs.columbia.edu>
---
 arch/arm64/include/asm/kvm_host.h | 2 +-
 arch/arm64/include/uapi/asm/kvm.h | 1 +
 arch/arm64/kvm/reset.c            | 8 ++++++++
 3 files changed, 10 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
index dcc4df8..6df0c7c 100644
--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h
@@ -39,7 +39,7 @@
 
 #define KVM_MAX_VCPUS VGIC_V3_MAX_CPUS
 
-#define KVM_VCPU_MAX_FEATURES 4
+#define KVM_VCPU_MAX_FEATURES 5
 
 #define KVM_REQ_SLEEP \
 	KVM_ARCH_REQ_FLAGS(0, KVM_REQUEST_WAIT | KVM_REQUEST_NO_WAKEUP)
diff --git a/arch/arm64/include/uapi/asm/kvm.h b/arch/arm64/include/uapi/asm/kvm.h
index 9f3ca24..4a71a72 100644
--- a/arch/arm64/include/uapi/asm/kvm.h
+++ b/arch/arm64/include/uapi/asm/kvm.h
@@ -99,6 +99,7 @@ struct kvm_regs {
 #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 */
 #define KVM_ARM_VCPU_PMU_V3		3 /* Support guest PMUv3 */
+#define KVM_ARM_VCPU_NESTED_VIRT	4 /* Support nested virtualization */
 
 struct kvm_vcpu_init {
 	__u32 target;
diff --git a/arch/arm64/kvm/reset.c b/arch/arm64/kvm/reset.c
index 3256b92..1353516 100644
--- a/arch/arm64/kvm/reset.c
+++ b/arch/arm64/kvm/reset.c
@@ -41,6 +41,11 @@
 			PSR_F_BIT | PSR_D_BIT),
 };
 
+static const struct kvm_regs default_regs_reset_el2 = {
+	.regs.pstate = (PSR_MODE_EL2h | PSR_A_BIT | PSR_I_BIT |
+			PSR_F_BIT | PSR_D_BIT),
+};
+
 static const struct kvm_regs default_regs_reset32 = {
 	.regs.pstate = (COMPAT_PSR_MODE_SVC | COMPAT_PSR_A_BIT |
 			COMPAT_PSR_I_BIT | COMPAT_PSR_F_BIT),
@@ -106,6 +111,9 @@ int kvm_reset_vcpu(struct kvm_vcpu *vcpu)
 			if (!cpu_has_32bit_el1())
 				return -EINVAL;
 			cpu_reset = &default_regs_reset32;
+		} else if (test_bit(KVM_ARM_VCPU_NESTED_VIRT,
+				    vcpu->arch.features)) {
+			cpu_reset = &default_regs_reset_el2;
 		} else {
 			cpu_reset = &default_regs_reset;
 		}
-- 
1.9.1