Re: [Xen-devel] [PATCH for-4.6] p2m/ept: Set the A bit only if PML is enabled

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 24.09.15 at 11:10, <tim@xxxxxxx> wrote:
> At 01:02 -0600 on 24 Sep (1443056566), Jan Beulich wrote:
>> --- a/xen/arch/x86/mm/p2m-ept.c
>> +++ b/xen/arch/x86/mm/p2m-ept.c
>> @@ -130,14 +130,18 @@ static void ept_p2m_type_to_flags(struct p2m_domain 
>> *p2m, ept_entry_t *entry,
>>              break;
>>          case p2m_ram_rw:
>>              entry->r = entry->w = entry->x = 1;
>> -            entry->a = entry->d = 1;
>> +            entry->a = entry->d = cpu_has_ept_ad;
>>              break;
>>          case p2m_mmio_direct:
>>              entry->r = entry->x = 1;
>>              entry->w = !rangeset_contains_singleton(mmio_ro_ranges,
>>                                                      entry->mfn);
>> -            entry->a = 1;
>> -            entry->d = entry->w;
>> +            entry->a = cpu_has_ept_ad;
>> +            entry->d = entry->w && cpu_has_ept_ad;
>>              break;
>>          case p2m_ram_logdirty:
>>              entry->r = entry->x = 1;
>> 
> 
> Sure, that works.  I still prefer putting the workaround on the CR3
> operation, so all the cost happens on the broken chip, but I'll shut
> up about that now. :)

And I agree to that for post-4.6. For 4.6 the easier to validate
fix still would seem to be a variation of what Ross posted.

Jan


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