BZ: https://bugzilla.tianocore.org/show_bug.cgi?id=2198
After having transitioned from UEFI to the OS, the OS will need to boot the APs. For an SEV-ES guest, the APs will have been parked by UEFI using GHCB pages allocated by UEFI. The hypervisor will write to the GHCB SW_EXITINFO2 field of the GHCB when the AP is booted. As a result, the GHCB pages must be marked reserved so that the OS does not attempt to use them and experience memory corruption because of the hypervisor write. Change the GHCB allocation from the default boot services memory to reserved memory. Cc: Jordan Justen <jordan.l.jus...@intel.com> Cc: Laszlo Ersek <ler...@redhat.com> Cc: Ard Biesheuvel <ard.biesheu...@linaro.org> Reviewed-by: Laszlo Ersek <ler...@redhat.com> Signed-off-by: Tom Lendacky <thomas.lenda...@amd.com> --- OvmfPkg/PlatformPei/AmdSev.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/OvmfPkg/PlatformPei/AmdSev.c b/OvmfPkg/PlatformPei/AmdSev.c index a2b38c591236..4a515a484720 100644 --- a/OvmfPkg/PlatformPei/AmdSev.c +++ b/OvmfPkg/PlatformPei/AmdSev.c @@ -51,9 +51,11 @@ AmdSevEsInitialize ( // // Allocate GHCB and per-CPU variable pages. + // Since the pages must survive across the UEFI to OS transition + // make them reserved. // GhcbPageCount = mMaxCpuCount * 2; - GhcbBase = AllocatePages (GhcbPageCount); + GhcbBase = AllocateReservedPages (GhcbPageCount); ASSERT (GhcbBase != NULL); GhcbBasePa = (PHYSICAL_ADDRESS)(UINTN) GhcbBase; -- 2.17.1 -=-=-=-=-=-=-=-=-=-=-=- Groups.io Links: You receive all messages sent to this group. View/Reply Online (#57907): https://edk2.groups.io/g/devel/message/57907 Mute This Topic: https://groups.io/mt/73212757/21656 Group Owner: devel+ow...@edk2.groups.io Unsubscribe: https://edk2.groups.io/g/devel/unsub [arch...@mail-archive.com] -=-=-=-=-=-=-=-=-=-=-=-
