Re: [PATCH v6 5/5] x86/sev: Add SNP-specific unaccepted memory support

[Tom Lendacky]

On 12/8/22 16:12, Kirill A. Shutemov wrote:
> On Thu, Dec 08, 2022 at 09:29:13AM -0600, Tom Lendacky 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.
> >
> > Since the boot path and the core kernel paths perform similar operations,
> > move the pvalidate_pages() and vmgexit_psc() functions into sev-shared.c
> > to avoid code duplication.
> >
> > Create the new header file arch/x86/boot/compressed/sev.h because adding
> > the function declaration to any of the existing SEV related header files
> > pulls in too many other header files, causing the build to fail.
> >
> > Signed-off-by: Tom Lendacky <thomas.lendacky@xxxxxxx>
> > ---
> >   arch/x86/Kconfig                |   1 +
> >   arch/x86/boot/compressed/mem.c  |   3 +
> >   arch/x86/boot/compressed/sev.c  |  54 ++++++++++++++-
> >   arch/x86/boot/compressed/sev.h  |  23 +++++++
> >   arch/x86/include/asm/sev.h      |   3 +
> >   arch/x86/kernel/sev-shared.c    | 103 +++++++++++++++++++++++++++++
> >   arch/x86/kernel/sev.c           | 112 ++++----------------------------
> >   arch/x86/mm/unaccepted_memory.c |   4 ++
> >   8 files changed, 204 insertions(+), 99 deletions(-)
> >   create mode 100644 arch/x86/boot/compressed/sev.h
> >
> > diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
> > index d88f61940aa7..0704d4795919 100644
> > --- a/arch/x86/Kconfig
> > +++ b/arch/x86/Kconfig
> > @@ -1549,6 +1549,7 @@ config AMD_MEM_ENCRYPT
> >   	select INSTRUCTION_DECODER
> >   	select ARCH_HAS_CC_PLATFORM
> >   	select X86_MEM_ENCRYPT
> > +	select UNACCEPTED_MEMORY
> >   	help
> >   	  Say yes to enable support for the encryption of system memory.
> >   	  This requires an AMD processor that supports Secure Memory
>
> I think it misses "depends on EFI_STUB".

Ah, good catch, thanks. I'll update the series to add that.

Thanks,
Tom

> The code I've submitted contains "select EFI_STUB", but it causes build
> issues for some configurations. I've changed it to "depends on" in git.