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

Borislav Petkov
2022-12-29T17:09:49Z

On Tue, Dec 27, 2022 at 03:49:39PM -0600, Kalra, Ashish wrote:
> Milan onward,

And before ML there's no SNP, right?

> 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?

Thx.

--
Regards/Gruss,
Boris.