linux-kernel - [PATCH v2 1/3] KVM: nVMX: Always call sync_vmcs02_to_vmcs12

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Date:   Thu, 14 Jan 2021 22:54:47 +0200
From:   Maxim Levitsky <mlevitsk@...hat.com>
To:     kvm@...r.kernel.org
Cc:     Thomas Gleixner <tglx@...utronix.de>, x86@...nel.org,
        Borislav Petkov <bp@...en8.de>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Ingo Molnar <mingo@...hat.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Joerg Roedel <joro@...tes.org>,
        Wanpeng Li <wanpengli@...cent.com>,
        "H. Peter Anvin" <hpa@...or.com>,
        Sean Christopherson <seanjc@...gle.com>,
        linux-kernel@...r.kernel.org, Jim Mattson <jmattson@...gle.com>,
        Maxim Levitsky <mlevitsk@...hat.com>
Subject: [PATCH v2 1/3] KVM: nVMX: Always call sync_vmcs02_to_vmcs12_rare on migration

Even when we are outside the nested guest, some vmcs02 fields
are not in sync vs vmcs12.

However during the migration, the vmcs12 has to be up to date
to be able to load it later after the migration.

To fix that, call that function.

Fixes: 7952d769c29ca ("KVM: nVMX: Sync rarely accessed guest fields only when needed")

Signed-off-by: Maxim Levitsky <mlevitsk@...hat.com>
---
 arch/x86/kvm/vmx/nested.c | 13 ++++++++-----
 1 file changed, 8 insertions(+), 5 deletions(-)

diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
index 0fbb46990dfce..776688f9d1017 100644
--- a/arch/x86/kvm/vmx/nested.c
+++ b/arch/x86/kvm/vmx/nested.c
@@ -6077,11 +6077,14 @@ static int vmx_get_nested_state(struct kvm_vcpu *vcpu,
 	if (is_guest_mode(vcpu)) {
 		sync_vmcs02_to_vmcs12(vcpu, vmcs12);
 		sync_vmcs02_to_vmcs12_rare(vcpu, vmcs12);
-	} else if (!vmx->nested.need_vmcs12_to_shadow_sync) {
-		if (vmx->nested.hv_evmcs)
-			copy_enlightened_to_vmcs12(vmx);
-		else if (enable_shadow_vmcs)
-			copy_shadow_to_vmcs12(vmx);
+	} else  {
+		copy_vmcs02_to_vmcs12_rare(vcpu, get_vmcs12(vcpu));
+		if (!vmx->nested.need_vmcs12_to_shadow_sync) {
+			if (vmx->nested.hv_evmcs)
+				copy_enlightened_to_vmcs12(vmx);
+			else if (enable_shadow_vmcs)
+				copy_shadow_to_vmcs12(vmx);
+		}
 	}
 
 	BUILD_BUG_ON(sizeof(user_vmx_nested_state->vmcs12) < VMCS12_SIZE);
-- 
2.26.2