[PATCH] x86/kvm/nVMX: set exit_qualification correctly when nested_vmx_load_msr() fails

[PATCH] x86/kvm/nVMX: set exit_qualification correctly when nested_vmx_load_msr() fails

[Vitaly Kuznetsov]

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@gmail.com>
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.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

Re: [PATCH] x86/kvm/nVMX: set exit_qualification correctly when nested_vmx_load_msr() fails

[Jim Mattson]

This looks similar to my "[PATCH] kvm: nVMX: Restore exit qual for
VM-entry failure due to MSR loading"

On Thu, Jul 12, 2018 at 4:35 AM, Vitaly Kuznetsov <vkuznets@redhat.com> wrote:
> 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@gmail.com>
> Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.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
>

Re: [PATCH] x86/kvm/nVMX: set exit_qualification correctly when nested_vmx_load_msr() fails

[Vitaly Kuznetsov]

Jim Mattson <jmattson@google.com> writes:

> This looks similar to my "[PATCH] kvm: nVMX: Restore exit qual for
> VM-entry failure due to MSR loading"
>

... which is still not in kvm/queue. Missed that, sorry! Let this one just
be a gentle ping then :-)

-- 
  Vitaly

Re: [PATCH] x86/kvm/nVMX: set exit_qualification correctly when nested_vmx_load_msr() fails

[Paolo Bonzini]

On 12/07/2018 18:57, Vitaly Kuznetsov wrote:
> Jim Mattson <jmattson@google.com> writes:
> 
>> This looks similar to my "[PATCH] kvm: nVMX: Restore exit qual for
>> VM-entry failure due to MSR loading"
>>
> 
> ... which is still not in kvm/queue. Missed that, sorry! Let this one just
> be a gentle ping then :-)
> 

I queued Jim's patch, thanks.

Paolo