Subject: [PATCH v2 04/94] KVM: arm64: nv: Reset VCPU to EL2 registers if VCPU nested virt is set

From: Marc Zyngier <[email-masked]>
Date: Tue, 11 Feb 2020 17:48:08 +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 | 32 ++++++++++++++++++++------------
 1 file changed, 20 insertions(+), 12 deletions(-)

diff --git a/arch/arm64/kvm/reset.c b/arch/arm64/kvm/reset.c
index 30b7ea680f66..5c50df274239 100644
--- a/arch/arm64/kvm/reset.c
+++ b/arch/arm64/kvm/reset.c
@@ -28,6 +28,7 @@
 #include <asm/kvm_coproc.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 */
@@ -36,15 +37,14 @@ static u32 kvm_ipa_limit;
 /*
  * ARMv8 Reset Values
  */
-static const struct kvm_regs default_regs_reset = {
-	.regs.pstate = (PSR_MODE_EL1h | PSR_A_BIT | PSR_I_BIT |
-			PSR_F_BIT | PSR_D_BIT),
-};
+#define VCPU_RESET_PSTATE_EL1	(PSR_MODE_EL1h | PSR_A_BIT | PSR_I_BIT | \
+				 PSR_F_BIT | PSR_D_BIT)
 
-static const struct kvm_regs default_regs_reset32 = {
-	.regs.pstate = (PSR_AA32_MODE_SVC | PSR_AA32_A_BIT |
-			PSR_AA32_I_BIT | PSR_AA32_F_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)
 
 static bool cpu_has_32bit_el1(void)
 {
@@ -260,6 +260,7 @@ int kvm_reset_vcpu(struct kvm_vcpu *vcpu)
 	const struct kvm_regs *cpu_reset;
 	int ret = -EINVAL;
 	bool loaded;
+	u32 pstate;
 
 	/* Reset PMU outside of the non-preemptible section */
 	kvm_pmu_vcpu_reset(vcpu);
@@ -288,18 +289,25 @@ 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 (!cpu_has_32bit_el1())
+			/*
+			 * The CPU must support 32bit EL1, and 32bit
+			 * NV is just not a thing...
+			 */
+			if (!cpu_has_32bit_el1() || nested_virt_in_use(vcpu))
 				goto out;
-			cpu_reset = &default_regs_reset32;
+			pstate = VCPU_RESET_PSTATE_SVC;
+		} else if (nested_virt_in_use(vcpu)) {
+			pstate = VCPU_RESET_PSTATE_EL2;
 		} else {
-			cpu_reset = &default_regs_reset;
+			pstate = VCPU_RESET_PSTATE_EL1;
 		}
 
 		break;
 	}
 
 	/* Reset core registers */
-	memcpy(vcpu_gp_regs(vcpu), cpu_reset, sizeof(*cpu_reset));
+	memset(vcpu_gp_regs(vcpu), 0, sizeof(*cpu_reset));
+	vcpu_gp_regs(vcpu)->regs.pstate = pstate;
 
 	/* Reset system registers */
 	kvm_reset_sys_regs(vcpu);
-- 
2.20.1

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