Subject: [PATCH v3 03/66] KVM: arm64: nv: Reset VCPU to EL2 registers if VCPU nested virt is set

From: Marc Zyngier <[email-masked]>
Date: Thu, 10 Dec 2020 15:58:59 +0000

From: Christoffer Dall <[email-masked]>

Reset the VCPU with PSTATE.M = EL2h when the nested virtualization
feature is enabled on the VCPU.

Signed-off-by: Christoffer Dall <[email-masked]>
[maz: rework register reset not to use empty data structures]
Signed-off-by: Marc Zyngier <[email-masked]>
---
 arch/arm64/kvm/reset.c | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/kvm/reset.c b/arch/arm64/kvm/reset.c
index 47f3f035f3ea..2d2c780e6c69 100644
--- a/arch/arm64/kvm/reset.c
+++ b/arch/arm64/kvm/reset.c
@@ -27,6 +27,7 @@
 #include <asm/kvm_asm.h>
 #include <asm/kvm_emulate.h>
 #include <asm/kvm_mmu.h>
+#include <asm/kvm_nested.h>
 #include <asm/virt.h>
 
 /* Maximum phys_shift supported for any VM on this host */
@@ -38,6 +39,9 @@ static u32 kvm_ipa_limit;
 #define VCPU_RESET_PSTATE_EL1	(PSR_MODE_EL1h | PSR_A_BIT | PSR_I_BIT | \
 				 PSR_F_BIT | PSR_D_BIT)
 
+#define VCPU_RESET_PSTATE_EL2	(PSR_MODE_EL2h | PSR_A_BIT | PSR_I_BIT | \
+				 PSR_F_BIT | PSR_D_BIT)
+
 #define VCPU_RESET_PSTATE_SVC	(PSR_AA32_MODE_SVC | PSR_AA32_A_BIT | \
 				 PSR_AA32_I_BIT | PSR_AA32_F_BIT)
 
@@ -224,11 +228,18 @@ int kvm_reset_vcpu(struct kvm_vcpu *vcpu)
 	switch (vcpu->arch.target) {
 	default:
 		if (test_bit(KVM_ARM_VCPU_EL1_32BIT, vcpu->arch.features)) {
-			if (!cpus_have_const_cap(ARM64_HAS_32BIT_EL1)) {
+			/*
+			 * The CPU must support 32bit EL1, and 32bit
+			 * NV is just not a thing...
+			 */
+			if (!cpus_have_const_cap(ARM64_HAS_32BIT_EL1) ||
+			    nested_virt_in_use(vcpu)) {
 				ret = -EINVAL;
 				goto out;
 			}
 			pstate = VCPU_RESET_PSTATE_SVC;
+		} else if (nested_virt_in_use(vcpu)) {
+			pstate = VCPU_RESET_PSTATE_EL2;
 		} else {
 			pstate = VCPU_RESET_PSTATE_EL1;
 		}
-- 
2.29.2

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