Re: [PATCH v4 4/4] x86/sev: Add SNP-specific unaccepted memory support

[Tom Lendacky]

On 8/25/22 17:10, Dionna Amalie Glaze wrote:
> > Add SNP-specific hooks to the unaccepted memory support in the boot
> > path (__accept_memory()) and the core kernel (accept_memory()) in order
> > to support booting SNP guests when unaccepted memory is present. Without
> > this support, SNP guests will fail to boot and/or panic() when unaccepted
> > memory is present in the EFI memory map.
> >
> > The process of accepting memory under SNP involves invoking the hypervisor
> > to perform a page state change for the page to private memory and then
> > issuing a PVALIDATE instruction to accept the page.
>
> Thanks for this update! Tests show the boot performance shaves off a
> good few seconds over eager acceptance, and it'll get better when we
> have on-demand pinning.
>
> The uncaught #VC exception is still there for 256GB machines and larger though.

Any chance of getting a stack trace when this occurs, e.g. adding a 
WARN_ON() in vc_handle_exitcode() (assuming it happens when logging is 
enabled)?

Thanks,
Tom

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