x86/efistub: Perform SNP feature test while running in the firmware

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Before refactoring the EFI stub boot flow to avoid the legacy bare metal
decompressor, duplicate the SNP feature check in the EFI stub before
handing over to the kernel proper.

The SNP feature check can be performed while running under the EFI boot
services, which means it can force the boot to fail gracefully and
return an error to the bootloader if the loaded kernel does not
implement support for all the features that the hypervisor enabled.

Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/r/20230807162720.545787-23-ardb@kernel.org

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This commit is contained in:

Ard Biesheuvel 2023-08-07 18:27:19 +02:00 • committed by Borislav Petkov (AMD)

parent bc5ddceff4

commit 31c77a5099

3 changed files with 87 additions and 46 deletions

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112

arch/x86/boot/compressed/sev.c

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4

arch/x86/include/asm/sev.h

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17

drivers/firmware/efi/libstub/x86-stub.c

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