linux-kernel - [PATCH] x86/kvm/nVMX: set exit_qualification correctly when nested_vmx_load

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Date:   Thu, 12 Jul 2018 13:35:05 +0200
From:   Vitaly Kuznetsov <vkuznets@...hat.com>
To:     kvm@...r.kernel.org
Cc:     Paolo Bonzini <pbonzini@...hat.com>,
        Radim Krčmář <rkrcmar@...hat.com>,
        x86@...nel.org, Wanpeng Li <kernellwp@...il.com>,
        KarimAllah Ahmed <karahmed@...zon.de>,
        linux-kernel@...r.kernel.org
Subject: [PATCH] x86/kvm/nVMX: set exit_qualification correctly when nested_vmx_load_msr() fails

Commit e79f245ddec1 ("X86/KVM: Properly update 'tsc_offset' to represent
the running guest") introduced a regression in enter_vmx_non_root_mode():
when nested_vmx_load_msr() fails exit_qualification needs to point to the
entry number we failed to validate. Intel's SDM states:

"VM-entry failure due to MSR loading. The exit qualification is loaded to
indicate which entry in the VM-entry MSR-load area caused the problem (1
for the first entry, 2 for the second, etc.)."

Fixes: e79f245ddec1 ("X86/KVM: Properly update 'tsc_offset' to represent the running guest")
Reported-by: Wanpeng Li <kernellwp@...il.com>
Signed-off-by: Vitaly Kuznetsov <vkuznets@...hat.com>
---
 arch/x86/kvm/vmx.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 65968649b365..be468c822892 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -11720,8 +11720,10 @@ static int enter_vmx_non_root_mode(struct kvm_vcpu *vcpu)
 	msr_entry_idx = nested_vmx_load_msr(vcpu,
 					    vmcs12->vm_entry_msr_load_addr,
 					    vmcs12->vm_entry_msr_load_count);
-	if (msr_entry_idx)
+	if (msr_entry_idx) {
+		exit_qual = msr_entry_idx;
 		goto fail;
+	}
 
 	/*
 	 * Note no nested_vmx_succeed or nested_vmx_fail here. At this point
-- 
2.14.4