linux-kernel - [RFC 03/55] KVM: arm64: Add KVM nesting feature

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Date:   Mon,  9 Jan 2017 01:23:59 -0500
From:   Jintack Lim <jintack@...columbia.edu>
To:     christoffer.dall@...aro.org, marc.zyngier@....com,
        pbonzini@...hat.com, rkrcmar@...hat.com, linux@...linux.org.uk,
        catalin.marinas@....com, will.deacon@....com,
        vladimir.murzin@....com, suzuki.poulose@....com,
        mark.rutland@....com, james.morse@....com,
        lorenzo.pieralisi@....com, kevin.brodsky@....com,
        wcohen@...hat.com, shankerd@...eaurora.org, geoff@...radead.org,
        andre.przywara@....com, eric.auger@...hat.com,
        anna-maria@...utronix.de, shihwei@...columbia.edu,
        linux-arm-kernel@...ts.infradead.org, kvmarm@...ts.cs.columbia.edu,
        kvm@...r.kernel.org, linux-kernel@...r.kernel.org
Cc:     jintack@...columbia.edu
Subject: [RFC 03/55] KVM: arm64: Add KVM nesting feature

From: Christoffer Dall <christoffer.dall@...aro.org>

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

Signed-off-by: Christoffer Dall <christoffer.dall@...aro.org>
Signed-off-by: Jintack Lim <jintack@...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 e505038..c0c8b02 100644
--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h
@@ -41,7 +41,7 @@
 
 #define KVM_MAX_VCPUS VGIC_V3_MAX_CPUS
 
-#define KVM_VCPU_MAX_FEATURES 4
+#define KVM_VCPU_MAX_FEATURES 5
 
 #define KVM_REQ_VCPU_EXIT	8
 
diff --git a/arch/arm64/include/uapi/asm/kvm.h b/arch/arm64/include/uapi/asm/kvm.h
index 3051f86..78117bf 100644
--- a/arch/arm64/include/uapi/asm/kvm.h
+++ b/arch/arm64/include/uapi/asm/kvm.h
@@ -97,6 +97,7 @@ 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 virtual EL2 */
 
 struct kvm_vcpu_init {
 	__u32 target;
diff --git a/arch/arm64/kvm/reset.c b/arch/arm64/kvm/reset.c
index 74322c2..e6b0b20 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),
@@ -124,6 +129,9 @@ 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