On Thu, Jul 4, 2013 at 3:10 PM, Gleb Natapov <gleb@xxxxxxxxxx> wrote:
> On Thu, Jul 04, 2013 at 09:00:09AM +0200, Paolo Bonzini wrote:
>> Il 03/07/2013 15:41, Arthur Chunqi Li ha scritto:
>> > Fix read/write to IA32_FEATURE_CONTROL MSR in nested environment.
>> > Simply return 0x5 when read and generate #GP(0) when write.
>> > Delete handling codes in vmx_set_vmx_msr() and generate #GP(0) in
>> > handle_wrmsr().
>> >
>> > Signed-off-by: Arthur Chunqi Li <yzt356@xxxxxxxxx>
>> > ---
>> > arch/x86/kvm/vmx.c | 5 +----
>> > 1 file changed, 1 insertion(+), 4 deletions(-)
>> >
>> > diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
>> > index 260a919..e125f94 100644
>> > --- a/arch/x86/kvm/vmx.c
>> > +++ b/arch/x86/kvm/vmx.c
>> > @@ -2277,7 +2277,7 @@ static int vmx_get_vmx_msr(struct kvm_vcpu *vcpu, u32 msr_index, u64 *pdata)
>> >
>> > switch (msr_index) {
>> > case MSR_IA32_FEATURE_CONTROL:
>> > - *pdata = 0;
>> > + *pdata = 0x5;
>> > break;
>>
>> This is not in the MSR_IA32_VMX_BASIC..MSR_IA32_VMX_TRUE_ENTRY_CTLS
>> range, so you must check nested_vmx_allowed and return 0 if it is false.
>>
> Or 1?
I think 1 is better here because this may return LOCK message when
query and tell OS not to write (if OS does such logical check)
>
>> Otherwise looks good.
>>
>> Paolo
>>
>> > case MSR_IA32_VMX_BASIC:
>> > /*
>> > @@ -2356,9 +2356,6 @@ static int vmx_set_vmx_msr(struct kvm_vcpu *vcpu, u32 msr_index, u64 data)
> Also this function is no longer needed. You can drop it.
>
> And what about Nadav's patch Bandan pointed too? It is not entirely
> correct, but it is close to real HW.
I think Nadav's patch is much closer to the HW scenario. However, I
think we don't need make things complex since KVM doen't support SMX
now and this MSR is always set to 0x5.
Arthur
>
>> > if (!nested_vmx_allowed(vcpu))
>> > return 0;
>> >
>> > - if (msr_index == MSR_IA32_FEATURE_CONTROL)
>> > - /* TODO: the right thing. */
>> > - return 1;
>> > /*
>> > * No need to treat VMX capability MSRs specially: If we don't handle
>> > * them, handle_wrmsr will #GP(0), which is correct (they are readonly)
>> >
>
> --
> Gleb.
--
To unsubscribe from this list: send the line "unsubscribe kvm" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
