x86/efi: Add GHCB mappings when SEV-ES is active

Calling down to EFI runtime services can result in the firmware performing
VMGEXIT calls. The firmware is likely to use the GHCB of the OS (e.g., for
setting EFI variables), so each GHCB in the system needs to be identity
mapped in the EFI page tables, as unencrypted, to avoid page faults.

Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
[ jroedel@suse.de: Moved GHCB mapping loop to sev-es.c ]
Signed-off-by: Joerg Roedel <jroedel@suse.de>
4 files changed