Re: [Xen-devel] [PATCHv2 for-4.6] p2m/ept: Work around hardware errata setting A bit

[Kai Huang <kaih.linux@xxxxxxxxx>]

On Mon, Sep 28, 2015 at 10:09 PM, Jan Beulich <JBeulich@xxxxxxxx> wrote:
>>>> On 28.09.15 at 14:39, <ross.lagerwall@xxxxxxxxxx> wrote:
>> --- a/xen/arch/x86/mm/p2m-ept.c
>> +++ b/xen/arch/x86/mm/p2m-ept.c
>> @@ -34,6 +34,8 @@
>>
>>  #include "mm-locks.h"
>>
>> +static bool_t __read_mostly cpu_has_ept_ad;
>
> This should be
> #define cpu_has_ept_ad (vmx_ept_vpid_cap & VMX_EPT_AD_BIT)
> put next to the respective other ones in vmx.h.

+1.

>
>> @@ -1150,6 +1152,9 @@ int ept_p2m_init(struct p2m_domain *p2m)
>>      p2m->memory_type_changed = ept_memory_type_changed;
>>      p2m->audit_p2m = NULL;
>>
>> +    /* Work around Errata AVR41 on Avaton processors. */
>> +    cpu_has_ept_ad = boot_cpu_data.x86_model != 0x4d;
>
> And this one then should turn off said flag (i.e. needs to be moved
> elsewhere).

However if cpu_has_ept_ad is going to be a macro definition as
suggested above, looks we need another variable.

>
> Plus PML initialization should get a respective check added.

My first thinking is checking whether cpu_has_ept_ad is set in ept_enable_pml.

Btw sorry I am taking vacation until Oct.8 so please expect slow
response if you need my comments.

Thanks,
-Kai

>
> Jan
>
>
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-- 
Thanks,
-Kai

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