lkml.org 
[lkml]   [2018]   [Jan]   [9]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [PATCH 1/7] KVM: x86: add SPEC_CTRL and IBPB_SUPPORT accessors
From
Date
On 09/01/2018 12:14, David Hildenbrand wrote:
>>
>> +/* These are scattered features in cpufeatures.h. */
>> +#define KVM_CPUID_BIT_AVX512_4VNNIW 2
>> +#define KVM_CPUID_BIT_AVX512_4FMAPS 3
>> +#define KVM_CPUID_BIT_SPEC_CTRL 26
>> +#define KVM_CPUID_BIT_STIBP 27
> I can see that STIBP is never checked in KVM code but only forwarded to
> the guest if available.
>
> I am wondering if we would have to check against that, too, before
> issuing a FEATURE_SET_IBPB.

STIBP is "single-threaded indirect branch prediction". SPEC_CTRL always
implies that FEATURE_SET_IBPB is available.

Paolo

\
 
 \ /
  Last update: 2018-01-14 23:19    [W:0.162 / U:0.996 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site