Re: [PATCH 11/12] x86/sev: Handle CLFLUSH MMIO events

[Joerg Roedel]

Hi Sean,

On Fri, Jul 30, 2021 at 10:42:30PM +0000, Sean Christopherson wrote:
> On Wed, Jul 21, 2021, Joerg Roedel wrote:
> This wording can be misread as "the hypervisor is responsible for _all_ cache
> management".  Maybe just:
> 
> 		/*
> 		 * Ignore CLFLUSHes - the hyperivsor is responsible for cache
> 		 * management of emulated MMIO.
> 		 */

Right, will update the comment, thanks.

> Side topic, out of curisoity, what's mapping/accessing emulated MMIO as non-UC?

The CLFLUSHes happen when the kexec'ed kernel maps the VGA framebuffer
as unencrypted. Initially it is mapped encrypted and before re-mapping
the kernel flushes the range from the caches.

I have not investigated why this doesn't happen on the first boot,
though.

Regards,

	Joerg