* [PATCH stable-5.4] KVM: x86: don't expose MSR_IA32_UMWAIT_CONTROL unconditionally
@ 2020-11-11 13:20 Jack Wang
2020-11-11 13:51 ` Paolo Bonzini
0 siblings, 1 reply; 3+ messages in thread
From: Jack Wang @ 2020-11-11 13:20 UTC (permalink / raw)
To: gregkh, sashal, stable; +Cc: Maxim Levitsky, Sean Christopherson, Paolo Bonzini
From: Maxim Levitsky <mlevitsk@redhat.com>
This msr is only available when the host supports WAITPKG feature.
This breaks a nested guest, if the L1 hypervisor is set to ignore
unknown msrs, because the only other safety check that the
kernel does is that it attempts to read the msr and
rejects it if it gets an exception.
Cc: stable@vger.kernel.org
Fixes: 6e3ba4abce ("KVM: vmx: Emulate MSR IA32_UMWAIT_CONTROL")
Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
Message-Id: <20200523161455.3940-3-mlevitsk@redhat.com>
Reviewed-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
(cherry picked from commit f4cfcd2d5aea4e96c5d483c476f3057b6b7baf6a
use boot_cpu_has for checking the feature)
Signed-off-by: Jack Wang <jinpu.wang@cloud.ionos.com>
---
arch/x86/kvm/x86.c | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 708b37274cb5..4cacf4669235 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -5226,6 +5226,10 @@ static void kvm_init_msr_list(void)
if (!kvm_x86_ops->rdtscp_supported())
continue;
break;
+ case MSR_IA32_UMWAIT_CONTROL:
+ if (!boot_cpu_has(X86_FEATURE_WAITPKG))
+ continue;
+ break;
case MSR_IA32_RTIT_CTL:
case MSR_IA32_RTIT_STATUS:
if (!kvm_x86_ops->pt_supported())
--
2.25.1
^ permalink raw reply related [flat|nested] 3+ messages in thread* Re: [PATCH stable-5.4] KVM: x86: don't expose MSR_IA32_UMWAIT_CONTROL unconditionally
2020-11-11 13:20 [PATCH stable-5.4] KVM: x86: don't expose MSR_IA32_UMWAIT_CONTROL unconditionally Jack Wang
@ 2020-11-11 13:51 ` Paolo Bonzini
2020-11-12 16:15 ` Sasha Levin
0 siblings, 1 reply; 3+ messages in thread
From: Paolo Bonzini @ 2020-11-11 13:51 UTC (permalink / raw)
To: Jack Wang, gregkh, sashal, stable; +Cc: Maxim Levitsky, Sean Christopherson
On 11/11/20 14:20, Jack Wang wrote:
> From: Maxim Levitsky <mlevitsk@redhat.com>
>
> This msr is only available when the host supports WAITPKG feature.
>
> This breaks a nested guest, if the L1 hypervisor is set to ignore
> unknown msrs, because the only other safety check that the
> kernel does is that it attempts to read the msr and
> rejects it if it gets an exception.
>
> Cc: stable@vger.kernel.org
> Fixes: 6e3ba4abce ("KVM: vmx: Emulate MSR IA32_UMWAIT_CONTROL")
> Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
> Message-Id: <20200523161455.3940-3-mlevitsk@redhat.com>
> Reviewed-by: Sean Christopherson <sean.j.christopherson@intel.com>
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
> (cherry picked from commit f4cfcd2d5aea4e96c5d483c476f3057b6b7baf6a
> use boot_cpu_has for checking the feature)
> Signed-off-by: Jack Wang <jinpu.wang@cloud.ionos.com>
> ---
> arch/x86/kvm/x86.c | 4 ++++
> 1 file changed, 4 insertions(+)
>
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index 708b37274cb5..4cacf4669235 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -5226,6 +5226,10 @@ static void kvm_init_msr_list(void)
> if (!kvm_x86_ops->rdtscp_supported())
> continue;
> break;
> + case MSR_IA32_UMWAIT_CONTROL:
> + if (!boot_cpu_has(X86_FEATURE_WAITPKG))
> + continue;
> + break;
> case MSR_IA32_RTIT_CTL:
> case MSR_IA32_RTIT_STATUS:
> if (!kvm_x86_ops->pt_supported())
>
Acked-by: Paolo Bonzini <pbonzini@redhat.com>
Thanks,
Paolo
^ permalink raw reply [flat|nested] 3+ messages in thread* Re: [PATCH stable-5.4] KVM: x86: don't expose MSR_IA32_UMWAIT_CONTROL unconditionally
2020-11-11 13:51 ` Paolo Bonzini
@ 2020-11-12 16:15 ` Sasha Levin
0 siblings, 0 replies; 3+ messages in thread
From: Sasha Levin @ 2020-11-12 16:15 UTC (permalink / raw)
To: Paolo Bonzini
Cc: Jack Wang, gregkh, stable, Maxim Levitsky, Sean Christopherson
On Wed, Nov 11, 2020 at 02:51:12PM +0100, Paolo Bonzini wrote:
>On 11/11/20 14:20, Jack Wang wrote:
>>From: Maxim Levitsky <mlevitsk@redhat.com>
>>
>>This msr is only available when the host supports WAITPKG feature.
>>
>>This breaks a nested guest, if the L1 hypervisor is set to ignore
>>unknown msrs, because the only other safety check that the
>>kernel does is that it attempts to read the msr and
>>rejects it if it gets an exception.
>>
>>Cc: stable@vger.kernel.org
>>Fixes: 6e3ba4abce ("KVM: vmx: Emulate MSR IA32_UMWAIT_CONTROL")
>>Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
>>Message-Id: <20200523161455.3940-3-mlevitsk@redhat.com>
>>Reviewed-by: Sean Christopherson <sean.j.christopherson@intel.com>
>>Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
>>(cherry picked from commit f4cfcd2d5aea4e96c5d483c476f3057b6b7baf6a
>>use boot_cpu_has for checking the feature)
>>Signed-off-by: Jack Wang <jinpu.wang@cloud.ionos.com>
>>---
>> arch/x86/kvm/x86.c | 4 ++++
>> 1 file changed, 4 insertions(+)
>>
>>diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
>>index 708b37274cb5..4cacf4669235 100644
>>--- a/arch/x86/kvm/x86.c
>>+++ b/arch/x86/kvm/x86.c
>>@@ -5226,6 +5226,10 @@ static void kvm_init_msr_list(void)
>> if (!kvm_x86_ops->rdtscp_supported())
>> continue;
>> break;
>>+ case MSR_IA32_UMWAIT_CONTROL:
>>+ if (!boot_cpu_has(X86_FEATURE_WAITPKG))
>>+ continue;
>>+ break;
>> case MSR_IA32_RTIT_CTL:
>> case MSR_IA32_RTIT_STATUS:
>> if (!kvm_x86_ops->pt_supported())
>>
>
>Acked-by: Paolo Bonzini <pbonzini@redhat.com>
Queued up, thanks!
--
Thanks,
Sasha
^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2020-11-12 16:15 UTC | newest]
Thread overview: 3+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2020-11-11 13:20 [PATCH stable-5.4] KVM: x86: don't expose MSR_IA32_UMWAIT_CONTROL unconditionally Jack Wang
2020-11-11 13:51 ` Paolo Bonzini
2020-11-12 16:15 ` Sasha Levin
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox