linux-kernel - [PATCH v2 4/7] KVM: nVMX: Force enlightened VMCS sync from nested_vmx

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Message-Id: <20210517135054.1914802-5-vkuznets@redhat.com>
Date:   Mon, 17 May 2021 15:50:51 +0200
From:   Vitaly Kuznetsov <vkuznets@...hat.com>
To:     kvm@...r.kernel.org, Paolo Bonzini <pbonzini@...hat.com>
Cc:     Sean Christopherson <seanjc@...gle.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Maxim Levitsky <mlevitsk@...hat.com>,
        linux-kernel@...r.kernel.org
Subject: [PATCH v2 4/7] KVM: nVMX: Force enlightened VMCS sync from nested_vmx_failValid()

'need_vmcs12_to_shadow_sync' is used for both shadow and enlightened
VMCS sync when we exit to L1. The comment in nested_vmx_failValid()
validly states why shadow vmcs sync can be omitted but this doesn't
apply to enlightened VMCS as it 'shadows' all VMCS12 fields.

Signed-off-by: Vitaly Kuznetsov <vkuznets@...hat.com>
---
 arch/x86/kvm/vmx/nested.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
index ec476f64df73..eb2d25a93356 100644
--- a/arch/x86/kvm/vmx/nested.c
+++ b/arch/x86/kvm/vmx/nested.c
@@ -194,9 +194,13 @@ static int nested_vmx_failValid(struct kvm_vcpu *vcpu,
 			| X86_EFLAGS_ZF);
 	get_vmcs12(vcpu)->vm_instruction_error = vm_instruction_error;
 	/*
-	 * We don't need to force a shadow sync because
-	 * VM_INSTRUCTION_ERROR is not shadowed
+	 * We don't need to force sync to shadow VMCS because
+	 * VM_INSTRUCTION_ERROR is not shadowed. Enlightened VMCS 'shadows' all
+	 * fields and thus must be synced.
 	 */
+	if (nested_evmcs_is_used(to_vmx(vcpu)))
+		to_vmx(vcpu)->nested.need_vmcs12_to_shadow_sync = true;
+
 	return kvm_skip_emulated_instruction(vcpu);
 }
 
-- 
2.31.1