linux-kernel - [PATCH] x86/kvm/nVMX: don't skip emulated instruction twice when vmptr address is not backed

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Date:   Wed,  9 Jan 2019 18:22:56 +0100
From:   Vitaly Kuznetsov <vkuznets@...hat.com>
To:     kvm@...r.kernel.org
Cc:     Paolo Bonzini <pbonzini@...hat.com>,
        Radim Krčmář <rkrcmar@...hat.com>,
        linux-kernel@...r.kernel.org, Andrew Jones <drjones@...hat.com>,
        Cornelia Huck <cohuck@...hat.com>,
        Jim Mattson <jmattson@...gle.com>,
        Sean Christopherson <sean.j.christopherson@...el.com>
Subject: [PATCH] x86/kvm/nVMX: don't skip emulated instruction twice when vmptr address is not backed

Since commit 09abb5e3e5e50 ("KVM: nVMX: call kvm_skip_emulated_instruction
in nested_vmx_{fail,succeed}") nested_vmx_failValid() results in
kvm_skip_emulated_instruction() so doing it again in handle_vmptrld() when
vmptr address is not backed is wrong, we end up advancing RIP twice.

Fixes: fca91f6d60b6e ("kvm: nVMX: Set VM instruction error for VMPTRLD of unbacked page")
Reported-by: Cornelia Huck <cohuck@...hat.com>
Signed-off-by: Vitaly Kuznetsov <vkuznets@...hat.com>
---
 arch/x86/kvm/vmx/nested.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
index 3170e291215d..2616bd2c7f2c 100644
--- a/arch/x86/kvm/vmx/nested.c
+++ b/arch/x86/kvm/vmx/nested.c
@@ -4540,9 +4540,8 @@ static int handle_vmptrld(struct kvm_vcpu *vcpu)
 			 * given physical address won't match the required
 			 * VMCS12_REVISION identifier.
 			 */
-			nested_vmx_failValid(vcpu,
+			return nested_vmx_failValid(vcpu,
 				VMXERR_VMPTRLD_INCORRECT_VMCS_REVISION_ID);
-			return kvm_skip_emulated_instruction(vcpu);
 		}
 		new_vmcs12 = kmap(page);
 		if (new_vmcs12->hdr.revision_id != VMCS12_REVISION ||
-- 
2.20.1