From: "Peter Gonda" <pgonda@google.com>
To: devel@edk2.groups.io
Cc: Peter Gonda <pgonda@google.com>,
James Bottomley <jejb@linux.ibm.com>, Min Xu <min.m.xu@intel.com>,
Jiewen Yao <jiewen.yao@intel.com>,
Tom Lendacky <thomas.lendacky@amd.com>,
Jordan Justen <jordan.l.justen@intel.com>,
Ard Biesheuvel <ardb+tianocore@kernel.org>,
Laszlo Ersek <lersek@redhat.com>,
Erdem Aktas <erdemaktas@google.com>,
Brijesh Singh <brijesh.singh@amd.com>,
Marc Orr <marcorr@google.com>
Subject: [PATCH v2] OvmfPkg/ResetVector: Removing SEV-ES CPUID bit check
Date: Thu, 13 Jan 2022 08:30:43 -0800 [thread overview]
Message-ID: <d8648fafbdbffe4c62dc65f1c2623c0a777c8f64.1642091427.git.pgonda@google.com> (raw)
The SEV-ES bit of Fn800-001F[EAX] - Bit 3 is used for a host to
determine support for running SEV-ES guests. It should not be checked by
a guest to determine if it is running under SEV-ES. The guest should use
the SEV_STATUS MSR Bit 1 to determine if SEV-ES is enabled. This check
was not part of the original SEV-ES support and was added in
a91b700e38. Removing the check makes this code consistent with the
Linux kernel
Fixes: a91b700e38 (Ovmf/ResetVector: Simplify and consolidate the SEV features checks)
Cc: James Bottomley <jejb@linux.ibm.com>
Cc: Min Xu <min.m.xu@intel.com>
Cc: Jiewen Yao <jiewen.yao@intel.com>
Cc: Tom Lendacky <thomas.lendacky@amd.com>
Cc: Jordan Justen <jordan.l.justen@intel.com>
Cc: Ard Biesheuvel <ardb+tianocore@kernel.org>
Cc: Laszlo Ersek <lersek@redhat.com>
Cc: Erdem Aktas <erdemaktas@google.com>
Cc: Brijesh Singh <brijesh.singh@amd.com>
Cc: Erdem Aktas <erdemaktas@google.com>
Cc: Marc Orr <marcorr@google.com>
Signed-off-by: Peter Gonda <pgonda@google.com>
---
OvmfPkg/ResetVector/Ia32/AmdSev.asm | 8 --------
1 file changed, 8 deletions(-)
diff --git a/OvmfPkg/ResetVector/Ia32/AmdSev.asm b/OvmfPkg/ResetVector/Ia32/AmdSev.asm
index 1f827da3b9..77692db27e 100644
--- a/OvmfPkg/ResetVector/Ia32/AmdSev.asm
+++ b/OvmfPkg/ResetVector/Ia32/AmdSev.asm
@@ -265,14 +265,6 @@ CheckSevFeatures:
; Set the work area header to indicate that the SEV is enabled
mov byte[WORK_AREA_GUEST_TYPE], 1
- ; Check for SEV-ES memory encryption feature:
- ; CPUID Fn8000_001F[EAX] - Bit 3
- ; CPUID raises a #VC exception if running as an SEV-ES guest
- mov eax, 0x8000001f
- cpuid
- bt eax, 3
- jnc GetSevEncBit
-
; Check if SEV-ES is enabled
; MSR_0xC0010131 - Bit 1 (SEV-ES enabled)
mov ecx, SEV_STATUS_MSR
--
2.34.1.575.g55b058a8bb-goog
next reply other threads:[~2022-01-13 16:30 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-01-13 16:30 Peter Gonda [this message]
2022-01-19 17:03 ` [PATCH v2] OvmfPkg/ResetVector: Removing SEV-ES CPUID bit check Lendacky, Thomas
2022-06-01 12:25 ` [PATCH V3] " Ard Biesheuvel
2022-06-01 13:16 ` Lendacky, Thomas
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