Move memory acceptance x86 arch code into EFI stub

This is a follow-up to [0].

Move arch_accept_memory(), which is only called by the EFI stub and never by the decompressor on a non-EFI boot, into the EFI stub, and avoid relying directly on decompressor APIs such as error().

Instead, call tdx_panic() on a failure to accept memory in a TDX guest.

This makes the decompressor's implementation of panic() obsolete, and allows it to be removed. This is a prerequisite for dropping the implementation of snprintf() from the EFI stub entirely, which is what the series containing [0] implements.

Changes since v1 [1]:
- Add missing stub for early_is_sevsnp_guest() when SEV support is compiled out but TDX support is built in.
- Use native_cpuid() in EFI stub code so it does not get paravirtualized
- Set __NO_FORTIFY when including tdx-shared.c so the decompressor/stub version does not get instrumented. Needed for the memcpy() in tdx_panic().

[0] http://lore.kernel.org/r/[email protected]
[1] https://lore.kernel.org/all/[email protected]/

Ard Biesheuvel (3):
x86/tdx: Share tdx_panic() with the EFI stub
x86/boot: Move unaccepted memory handling out of the decompressor x86/boot: Drop unused implementation of panic()

 arch/x86/boot/compressed/error.c        | 19 ---------
 arch/x86/boot/compressed/error.h        |  1 -
 arch/x86/boot/compressed/mem.c          | 42 --------------------
 arch/x86/boot/compressed/sev.h          |  2 -
 arch/x86/boot/compressed/tdx-shared.c   |  2 +
 arch/x86/coco/tdx/tdx-shared.c          | 31 +++++++++++++++
 arch/x86/coco/tdx/tdx.c                 | 35 ----------------
 arch/x86/include/asm/sev.h              |  2 +
 arch/x86/include/asm/shared/tdx.h       |  1 +
 drivers/firmware/efi/libstub/x86-stub.c | 39 ++++++++++++++++++
 10 files changed, 75 insertions(+), 99 deletions(-)

2.53.0