lkml.org 
[lkml]   [2016]   [Jul]   [30]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
Date
SubjectRe: [RFC PATCH 4/4] KVM: vmx: add support for emulating UMIP
2016-07-14 16:09 GMT+08:00 Paolo Bonzini <pbonzini@redhat.com>:
[...]
>
> This is not necessary because this is how KVM computes
> CPUID[EAX=7,EBX=0].ECX:
>
> unsigned f_umip = kvm_x86_ops->umip_emulated() ? F(UMIP) : 0;
> ...
> const u32 kvm_cpuid_7_0_ecx_x86_features = F(PKU) | F(UMIP);
> ...
> // Mask userspace-provided value against supported features
> entry->ecx &= kvm_cpuid_7_0_ecx_x86_features;
> // Mask userspace-provided value against host features
> cpuid_mask(&entry->ecx, CPUID_7_ECX);
> // Finally add emulated features
> entry->ecx |= f_umip;

I think you mean:

- entry->ecx -> userspace-provided value
- kvm_cpuid_7_0_ecx_x86_features -> supported features
- CPUID_7_ECX -> host features

However, entry->ecx is returned by cpuid instruction
(do_cpuid_1_ent()), so why it is a userspace-provided value?

Regards,
Wanpeng Li

\
 
 \ /
  Last update: 2016-07-31 05:21    [W:0.143 / U:1.460 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site