[edk2-devel] [PATCH v3 04/15] OvmfPkg/ResetVector: Perform a simple SEV-ES sanity check
Lendacky, Thomas
thomas.lendacky at amd.com
Thu Jan 7 18:48:14 UTC 2021
From: Tom Lendacky <thomas.lendacky at amd.com>
BZ: https://bugzilla.tianocore.org/show_bug.cgi?id=3108
If a hypervisor incorrectly reports through CPUID that SEV-ES is not
active, ensure that a #VC exception was not taken. If it is found that
a #VC was taken, then the code enters a HLT loop.
Cc: Jordan Justen <jordan.l.justen at intel.com>
Cc: Laszlo Ersek <lersek at redhat.com>
Cc: Ard Biesheuvel <ard.biesheuvel at arm.com>
Cc: Brijesh Singh <brijesh.singh at amd.com>
Reviewed-by: Laszlo Ersek <lersek at redhat.com>
Signed-off-by: Tom Lendacky <thomas.lendacky at amd.com>
---
OvmfPkg/ResetVector/Ia32/PageTables64.asm | 16 ++++++++++++++++
1 file changed, 16 insertions(+)
diff --git a/OvmfPkg/ResetVector/Ia32/PageTables64.asm b/OvmfPkg/ResetVector/Ia32/PageTables64.asm
index ccc95ad4715d..a1771dfdec23 100644
--- a/OvmfPkg/ResetVector/Ia32/PageTables64.asm
+++ b/OvmfPkg/ResetVector/Ia32/PageTables64.asm
@@ -154,6 +154,22 @@ SevEncBitLowHlt:
jmp SevEncBitLowHlt
NoSev:
+ ;
+ ; Perform an SEV-ES sanity check by seeing if a #VC exception occurred.
+ ;
+ cmp byte[SEV_ES_WORK_AREA], 0
+ jz NoSevPass
+
+ ;
+ ; A #VC was received, yet CPUID indicates no SEV-ES support, something
+ ; isn't right.
+ ;
+NoSevEsVcHlt:
+ cli
+ hlt
+ jmp NoSevEsVcHlt
+
+NoSevPass:
xor eax, eax
SevExit:
--
2.30.0
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