* [PATCH] KVM: x86: svm: report MSR_IA32_MCG_EXT_CTL as unsupported
@ 2018-12-19 11:06 Vitaly Kuznetsov
2018-12-20 20:06 ` Radim Krčmář
0 siblings, 1 reply; 4+ messages in thread
From: Vitaly Kuznetsov @ 2018-12-19 11:06 UTC (permalink / raw)
To: kvm
Cc: Paolo Bonzini, Radim Krčmář,
linux-kernel, Tom Lendacky, Joerg Roedel, x86
AMD doesn't seem to implement MSR_IA32_MCG_EXT_CTL and svm code in kvm
knows nothing about it, however, this MSR is among emulated_msrs and
thus returned with KVM_GET_MSR_INDEX_LIST. The consequent KVM_GET_MSRS,
of course, fails.
Report the MSR as unsupported to not confuse userspace.
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
---
arch/x86/kvm/svm.c | 7 +++++++
1 file changed, 7 insertions(+)
diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index 2acb42b74a51..dfdf7d0b7f88 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -5845,6 +5845,13 @@ static bool svm_cpu_has_accelerated_tpr(void)
static bool svm_has_emulated_msr(int index)
{
+ switch (index) {
+ case MSR_IA32_MCG_EXT_CTL:
+ return false;
+ default:
+ break;
+ }
+
return true;
}
--
2.19.2
^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [PATCH] KVM: x86: svm: report MSR_IA32_MCG_EXT_CTL as unsupported
2018-12-19 11:06 [PATCH] KVM: x86: svm: report MSR_IA32_MCG_EXT_CTL as unsupported Vitaly Kuznetsov
@ 2018-12-20 20:06 ` Radim Krčmář
2018-12-21 10:06 ` Vitaly Kuznetsov
0 siblings, 1 reply; 4+ messages in thread
From: Radim Krčmář @ 2018-12-20 20:06 UTC (permalink / raw)
To: Vitaly Kuznetsov
Cc: kvm, Paolo Bonzini, linux-kernel, Tom Lendacky, Joerg Roedel, x86
2018-12-19 12:06+0100, Vitaly Kuznetsov:
> AMD doesn't seem to implement MSR_IA32_MCG_EXT_CTL and svm code in kvm
> knows nothing about it, however, this MSR is among emulated_msrs and
> thus returned with KVM_GET_MSR_INDEX_LIST. The consequent KVM_GET_MSRS,
> of course, fails.
>
> Report the MSR as unsupported to not confuse userspace.
>
> Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
> ---
> arch/x86/kvm/svm.c | 7 +++++++
> 1 file changed, 7 insertions(+)
>
> diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
> index 2acb42b74a51..dfdf7d0b7f88 100644
> --- a/arch/x86/kvm/svm.c
> +++ b/arch/x86/kvm/svm.c
> @@ -5845,6 +5845,13 @@ static bool svm_cpu_has_accelerated_tpr(void)
>
> static bool svm_has_emulated_msr(int index)
> {
> + switch (index) {
> + case MSR_IA32_MCG_EXT_CTL:
> + return false;
> + default:
> + break;
Queued, thanks.
Btw, I would prefer this without the
default: break;
as I don't think we'll ever add something there.
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] KVM: x86: svm: report MSR_IA32_MCG_EXT_CTL as unsupported
2018-12-20 20:06 ` Radim Krčmář
@ 2018-12-21 10:06 ` Vitaly Kuznetsov
2018-12-21 11:18 ` Paolo Bonzini
0 siblings, 1 reply; 4+ messages in thread
From: Vitaly Kuznetsov @ 2018-12-21 10:06 UTC (permalink / raw)
To: Radim Krčmář
Cc: kvm, Paolo Bonzini, linux-kernel, Tom Lendacky, Joerg Roedel, x86
Radim Krčmář <rkrcmar@redhat.com> writes:
> 2018-12-19 12:06+0100, Vitaly Kuznetsov:
>> AMD doesn't seem to implement MSR_IA32_MCG_EXT_CTL and svm code in kvm
>> knows nothing about it, however, this MSR is among emulated_msrs and
>> thus returned with KVM_GET_MSR_INDEX_LIST. The consequent KVM_GET_MSRS,
>> of course, fails.
>>
>> Report the MSR as unsupported to not confuse userspace.
>>
>> Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
>> ---
>> arch/x86/kvm/svm.c | 7 +++++++
>> 1 file changed, 7 insertions(+)
>>
>> diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
>> index 2acb42b74a51..dfdf7d0b7f88 100644
>> --- a/arch/x86/kvm/svm.c
>> +++ b/arch/x86/kvm/svm.c
>> @@ -5845,6 +5845,13 @@ static bool svm_cpu_has_accelerated_tpr(void)
>>
>> static bool svm_has_emulated_msr(int index)
>> {
>> + switch (index) {
>> + case MSR_IA32_MCG_EXT_CTL:
>> + return false;
>> + default:
>> + break;
>
> Queued, thanks.
>
> Btw, I would prefer this without the
>
> default: break;
>
> as I don't think we'll ever add something there.
"640K ought to be enough for anybody" :-)
But in case you commit it as
return index != MSR_IA32_MCG_EXT_CTL;
I won't object. Thanks,
--
Vitaly
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] KVM: x86: svm: report MSR_IA32_MCG_EXT_CTL as unsupported
2018-12-21 10:06 ` Vitaly Kuznetsov
@ 2018-12-21 11:18 ` Paolo Bonzini
0 siblings, 0 replies; 4+ messages in thread
From: Paolo Bonzini @ 2018-12-21 11:18 UTC (permalink / raw)
To: Vitaly Kuznetsov, Radim Krčmář
Cc: kvm, linux-kernel, Tom Lendacky, Joerg Roedel, x86
On 21/12/18 11:06, Vitaly Kuznetsov wrote:
>> Btw, I would prefer this without the
>>
>> default: break;
>>
>> as I don't think we'll ever add something there.
>
> "640K ought to be enough for anybody" :-)
>
> But in case you commit it as
>
> return index != MSR_IA32_MCG_EXT_CTL;
>
> I won't object. Thanks,
Radim committed it as it, but I think he did want the switch statement
(hey, vmx_has_emulated_msr has *two* cases!). It's just the "default:
break;" that is unnecessary or could be "default: return true;".
Paolo
^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2018-12-21 11:18 UTC | newest]
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2018-12-19 11:06 [PATCH] KVM: x86: svm: report MSR_IA32_MCG_EXT_CTL as unsupported Vitaly Kuznetsov
2018-12-20 20:06 ` Radim Krčmář
2018-12-21 10:06 ` Vitaly Kuznetsov
2018-12-21 11:18 ` Paolo Bonzini
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