Re: [Xen-devel] [PATCH v2 4/6] xen/x86: disable global pages for domains with XPTI active

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 09.03.18 at 15:40, <jgross@xxxxxxxx> wrote:
> On 08/03/18 16:06, Jan Beulich wrote:
>>>>> On 02.03.18 at 09:14, <jgross@xxxxxxxx> wrote:
>>> @@ -123,22 +142,14 @@ unsigned int flush_area_local(const void *va, 
>>> unsigned int flags)
>>>              u32 t = pre_flush();
>>>  
>>>              if ( !cpu_has_invpcid )
>>> -            {
>>> -                unsigned long cr4 = read_cr4();
>>> -
>>> -                write_cr4(cr4 & ~X86_CR4_PGE);
>>> -                barrier();
>>> -                write_cr4(cr4);
>>> -            }
>>> +                do_flush_tlb(0);
>>>              else
>>> -            {
>>>                  /*
>>>                   * Using invpcid to flush all mappings works
>>>                   * regardless of whether PCID is enabled or not.
>>>                   * It is faster than read-modify-write CR4.
>>>                   */
>>>                  invpcid_flush_all();
>>> -            }
>> 
>> Btw, this is correct for FLUSH_TLB_GLOBAL, but goes too far for
>> FLUSH_TLB.
> 
> You are aware that my patches didn't change anything in this regard?

Oh, indeed - I've just responded to Wei's patch.

Jan


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