lkml.org 
[lkml]   [2016]   [Jul]   [13]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [RFC PATCH 4/4] KVM: vmx: add support for emulating UMIP
From
Date


On 13/07/2016 11:21, Yang Zhang wrote:
>>
>> + if ((cr4 & X86_CR4_UMIP) && !boot_cpu_has(X86_FEATURE_UMIP)) {
>> + vmcs_set_bits(SECONDARY_VM_EXEC_CONTROL,
>> + SECONDARY_EXEC_DESC);
>> + hw_cr4 &= ~X86_CR4_UMIP;
>> + } else
>> + vmcs_clear_bits(SECONDARY_VM_EXEC_CONTROL,
>> + SECONDARY_EXEC_DESC);
>> +
>
> Since the faults based on privilege level have priority over VM exits.
> So we don't need to enable/disable SECONDARY_EXEC_DESC dynamically.
> Instead, we can set it unconditionally.

I'm setting it dynamically because it slows down LGDT, LLDT, LIDT and LTR.

Paolo

\
 
 \ /
  Last update: 2016-07-13 12:01    [W:0.143 / U:0.032 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site