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| author | Tom Lendacky <thomas.lendacky@amd.com> | 2020-08-12 15:21:40 -0500 |
|---|---|---|
| committer | mergify[bot] <37929162+mergify[bot]@users.noreply.github.com> | 2020-08-17 02:46:39 +0000 |
| commit | 13ed9e5fc052e4c6db257fdec6f427192f88870c (patch) | |
| tree | 01f6773138b2454c8023caf3b560bb8eba438635 /OvmfPkg | |
| parent | 449a6e493418c337752b68e4f199bd2d7d39af9f (diff) | |
| download | edk2-13ed9e5fc052e4c6db257fdec6f427192f88870c.tar.gz edk2-13ed9e5fc052e4c6db257fdec6f427192f88870c.tar.bz2 edk2-13ed9e5fc052e4c6db257fdec6f427192f88870c.zip | |
OvmfPkg/PlatformPei: Move early GDT into ram when SEV-ES is enabled
BZ: https://bugzilla.tianocore.org/show_bug.cgi?id=2198
The SEV support will clear the C-bit from non-RAM areas. The early GDT
lives in a non-RAM area, so when an exception occurs (like a #VC) the GDT
will be read as un-encrypted even though it is encrypted. This will result
in a failure to be able to handle the exception.
Move the GDT into RAM so it can be accessed without error when running as
an SEV-ES guest.
Cc: Jordan Justen <jordan.l.justen@intel.com>
Cc: Laszlo Ersek <lersek@redhat.com>
Cc: Ard Biesheuvel <ard.biesheuvel@arm.com>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>
Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
Regression-tested-by: Laszlo Ersek <lersek@redhat.com>
Diffstat (limited to 'OvmfPkg')
| -rw-r--r-- | OvmfPkg/PlatformPei/AmdSev.c | 18 |
1 files changed, 18 insertions, 0 deletions
diff --git a/OvmfPkg/PlatformPei/AmdSev.c b/OvmfPkg/PlatformPei/AmdSev.c index 4fd4534cab..a2b38c5912 100644 --- a/OvmfPkg/PlatformPei/AmdSev.c +++ b/OvmfPkg/PlatformPei/AmdSev.c @@ -39,6 +39,8 @@ AmdSevEsInitialize ( PHYSICAL_ADDRESS GhcbBasePa;
UINTN GhcbPageCount, PageCount;
RETURN_STATUS PcdStatus, DecryptStatus;
+ IA32_DESCRIPTOR Gdtr;
+ VOID *Gdt;
if (!MemEncryptSevEsIsEnabled ()) {
return;
@@ -83,6 +85,22 @@ AmdSevEsInitialize ( (UINT64)GhcbPageCount, GhcbBase));
AsmWriteMsr64 (MSR_SEV_ES_GHCB, GhcbBasePa);
+
+ //
+ // The SEV support will clear the C-bit from non-RAM areas. The early GDT
+ // lives in a non-RAM area, so when an exception occurs (like a #VC) the GDT
+ // will be read as un-encrypted even though it was created before the C-bit
+ // was cleared (encrypted). This will result in a failure to be able to
+ // handle the exception.
+ //
+ AsmReadGdtr (&Gdtr);
+
+ Gdt = AllocatePages (EFI_SIZE_TO_PAGES ((UINTN) Gdtr.Limit + 1));
+ ASSERT (Gdt != NULL);
+
+ CopyMem (Gdt, (VOID *) Gdtr.Base, Gdtr.Limit + 1);
+ Gdtr.Base = (UINTN) Gdt;
+ AsmWriteGdtr (&Gdtr);
}
/**
|