On 11/01/2018 03:47, Tim Chen wrote:
> On 01/08/2018 10:08 AM, Paolo Bonzini wrote:
>
>> @@ -9597,6 +9620,9 @@ static void __noclone vmx_vcpu_run(struct kvm_vcpu
>> *vcpu)
>>
>> pt_guest_enter(vmx);
>>
>> +if (have_spec_ctrl && vmx->spec_ctrl != 0)
>> +wrmsrl(MSR_IA32_SPE
On 01/08/2018 10:08 AM, Paolo Bonzini wrote:
> @@ -9597,6 +9620,9 @@ static void __noclone vmx_vcpu_run(struct kvm_vcpu
> *vcpu)
>
> pt_guest_enter(vmx);
>
> + if (have_spec_ctrl && vmx->spec_ctrl != 0)
> + wrmsrl(MSR_IA32_SPEC_CTRL, vmx->spec_ctrl);
> +
Say host uses I
On 09/01/2018 00:19, Jim Mattson wrote:
+ vmx_disable_intercept_for_msr(MSR_IA32_SPEC_CTRL, false);
+ vmx_disable_intercept_for_msr(MSR_IA32_PRED_CMD, false);
>>> I have a lot of changes to MSR permission bitmap handling, but these
>>> intercepts should only be disabled when g
: jmatt...@google.com, aligu...@amazon.com, "thomas lendacky"
>> , b...@alien8.de
>>> Sent: Monday, January 8, 2018 8:41:07 PM
>>> Subject: Re: [PATCH 3/7] kvm: vmx: pass MSR_IA32_SPEC_CTRL and
>> MSR_IA32_PRED_CMD down to the guest
>>>
&g
> , b...@alien8.de
> > Sent: Monday, January 8, 2018 8:41:07 PM
> > Subject: Re: [PATCH 3/7] kvm: vmx: pass MSR_IA32_SPEC_CTRL and
> MSR_IA32_PRED_CMD down to the guest
> >
> > On Mon, 2018-01-08 at 19:08 +0100, Paolo Bonzini wrote:
> > >
> > > +
On Mon, Jan 8, 2018 at 2:32 PM, Paolo Bonzini wrote:
>
>> I have:
>>
>> if (!have_spec_ctrl ||
>> (!msr_info->host_initiated &&
>> !guest_cpuid_has(vcpu, X86_FEATURE_SPEC_CTRL)))
>> return 1;
>> msr_info->data = to_vmx(vcpu)->msr_ia32_spec_ctrl;
>> break;
>
>> I have:
>>
>> if (!have_spec
, 2018 8:41:07 PM
> Subject: Re: [PATCH 3/7] kvm: vmx: pass MSR_IA32_SPEC_CTRL and
> MSR_IA32_PRED_CMD down to the guest
>
> On Mon, 2018-01-08 at 19:08 +0100, Paolo Bonzini wrote:
> >
> > + if (have_spec_ctrl && vmx->spec_ctrl != 0)
> > +
> I have:
>
> if (!have_spec_ctrl ||
> (!msr_info->host_initiated &&
> !guest_cpuid_has(vcpu, X86_FEATURE_SPEC_CTRL)))
> return 1;
> msr_info->data = to_vmx(vcpu)->msr_ia32_spec_ctrl;
> break;
> I have:
>
> if (!have_spec_ctrl ||
> (!msr_info->host_initiated &&
> !guest_cpuid_
j"
>
> Sent: Monday, January 8, 2018 11:09:53 PM
> Subject: Re: [PATCH 3/7] kvm: vmx: pass MSR_IA32_SPEC_CTRL and
> MSR_IA32_PRED_CMD down to the guest
>
> Hi Paolo
>
> Do you assume that host isn't using IBRS and only guest uses it?
For now, yes.
Patches to
Hi Paolo
Do you assume that host isn't using IBRS and only guest uses it?
On Mon, Jan 8, 2018 at 10:08 AM, Paolo Bonzini wrote:
> Direct access to MSR_IA32_SPEC_CTRL and MSR_IA32_PRED_CMD is important
> for performance. Allow load/store of MSR_IA32_SPEC_CTRL, restore guest
> IBRS on VM entry
On 08/01/18 21:18, Jim Mattson wrote:
Guest usage of MSR_IA32_SPEC_CTRL and MSR_IA32_PRED_CMD should be
predicated on guest_cpuid_has(vcpu, X86_FEATURE_SPEC_CTRL).
On Mon, Jan 8, 2018 at 10:08 AM, Paolo Bonzini wrote:
Direct access to MSR_IA32_SPEC_CTRL and MSR_IA32_PRED_CMD is important
for
On Mon, 2018-01-08 at 19:08 +0100, Paolo Bonzini wrote:
>
> + if (have_spec_ctrl && vmx->spec_ctrl != 0)
> + wrmsrl(MSR_IA32_SPEC_CTRL, vmx->spec_ctrl);
> +
I think this one probably *is* safe even without an 'else lfence',
which means that the CPU can speculate around it, but
On 08/01/18 20:08, Paolo Bonzini wrote:
Direct access to MSR_IA32_SPEC_CTRL and MSR_IA32_PRED_CMD is important
for performance. Allow load/store of MSR_IA32_SPEC_CTRL, restore guest
IBRS on VM entry and set it to 0 on VM exit (because Linux does not use
it yet).
Signed-off-by: Paolo Bonzini
Guest usage of MSR_IA32_SPEC_CTRL and MSR_IA32_PRED_CMD should be
predicated on guest_cpuid_has(vcpu, X86_FEATURE_SPEC_CTRL).
On Mon, Jan 8, 2018 at 10:08 AM, Paolo Bonzini wrote:
> Direct access to MSR_IA32_SPEC_CTRL and MSR_IA32_PRED_CMD is important
> for performance. Allow load/store of MSR_
On Mon, Jan 08, 2018 at 07:08:41PM +0100, Paolo Bonzini wrote:
> Direct access to MSR_IA32_SPEC_CTRL and MSR_IA32_PRED_CMD is important
> for performance. Allow load/store of MSR_IA32_SPEC_CTRL, restore guest
> IBRS on VM entry and set it to 0 on VM exit (because Linux does not use
> it yet).
>
>
Direct access to MSR_IA32_SPEC_CTRL and MSR_IA32_PRED_CMD is important
for performance. Allow load/store of MSR_IA32_SPEC_CTRL, restore guest
IBRS on VM entry and set it to 0 on VM exit (because Linux does not use
it yet).
Signed-off-by: Paolo Bonzini
---
arch/x86/kvm/vmx.c | 32 +++
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