Re: [PATCH v7 6/6] x86/efi: Safely enable unaccepted memory in UEFI

Dave Hansen
2023-04-04T17:57:59Z

On 4/4/23 10:45, Kirill A. Shutemov wrote:
> I still think it is a bad idea.
>
> As I asked before, please include my
>
> Nacked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
>
> into the patch.

I was pretty opposed to this when I first saw it too. But, Tom and
company have worn down my opposition a bit.

The fact is that we have upstream kernels out there with SEV-SNP support
that don't know anything about unaccepted memory. They're either
relegated to using the pre-accepted memory (4GB??) or _some_ entity
needs to accept the memory. That entity obviously can't be the kernel
unless we backport unaccepted memory support.

This both lets the BIOS be the page-accepting entity _and_ allows the
entity to delegate that to the kernel when it needs to.

As much as I want to nak this and pretend that that those existing
kernel's don't exist, my powers of self-delusion do have their limits.

If our AMD friends don't do this, what is their alternative?