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SubjectRe: [PATCH Part2 v6 07/49] x86/sev: Invalid pages from direct map when adding it to RMP table
Hello Boris,

On 12/29/2022 11:09 AM, Borislav Petkov wrote:
> On Tue, Dec 27, 2022 at 03:49:39PM -0600, Kalra, Ashish wrote:
>> Milan onward,
> And before ML there's no SNP, right?

Yes, that's correct.

>> there is H/W support for coherency between mappings of the
>> same physical page with different encryption keys, so AFAIK, there should be
>> no need to flush during page state transitions, where we invoke these direct
>> map interface functions for re-mapping/invalidating pages.
> Yah, that rings a bell.
> In any case, the fact that flushing is not needed should be stated
> somewhere in text so that it is clear why.
>> I don't know if there is any other reason to flush after modifying
>> the direct map ?
> There's
> /*
> * No need to flush, when we did not set any of the caching
> * attributes:
> */
> cache = !!pgprot2cachemode(mask_set);
> Does the above HW cover this case too?

Actually, as both set_memory_p() and set_memory_np() are only
setting/clearing the _PAGE_PRESENT flag and not changing any of the page
caching attributes so this flush won't be required anyway.


> Thx.

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