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

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From: Ard Biesheuvel <ardb@kernel.org>

[ Commit 31c77a5099 upstream ]

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
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

...

This commit is contained in:

Ard Biesheuvel 2024-03-04 12:19:50 +01:00 • committed by Greg Kroah-Hartman

parent 77330c123d

commit fff7614f57

3 changed files with 88 additions and 46 deletions

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112

arch/x86/boot/compressed/sev.c

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5

arch/x86/include/asm/sev.h

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17

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

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