Re: [Xen-devel] [PATCH RFC] tools/libxc, xen/x86: Added xc_set_mem_access_sparse()

[Razvan Cojocaru <rcojocaru@xxxxxxxxxxxxxxx>]

On 08/29/2016 03:11 PM, Razvan Cojocaru wrote:
> On 08/26/2016 10:18 AM, Jan Beulich wrote:
>>>>> On 26.08.16 at 08:11, <rcojocaru@xxxxxxxxxxxxxxx> wrote:
>>> +        rc = p2m_set_mem_access(d, _gfn(mao.pfn), arr, mao.nr, start_iter,
>>> +                                MEMOP_CMD_MASK, mao.access, 0);
>>
>> Please don't pass mao.pfn here when it's meant to be ignore by
>> the caller. Use GFN_INVALID instead. And for future extensibility
>> please check that the caller put some pre-defined pattern here
>> (not sure whether zero is appropriate in this case).
> 
> GFN_INVALID has it's own semantics in p2m_set_mem_access():
> 
>     /* If request to set default access. */
>     if ( gfn_eq(gfn, INVALID_GFN) )
>     {
>         p2m->default_access = a;
>         return 0;
>     }
> 
> I'll replace the condition with "if ( !arr && gfn_eq(gfn, INVALID_GFN)
> )" and use GFN_INVALID in the XENMEM_access_op_set_access_multi (renamed
> from XENMEM_access_op_set_access_sparse), as recommended.

Sorry for the reversals, it obviously should say "INVALID_GFN"
everywhere. :)


Thanks,
Razvan

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