From: Leo Duran <leo.duran@amd.com>
To: devel@edk2.groups.io
Cc: Leo Duran <leo.duran@amd.com>, Eric Dong <eric.dong@intel.com>,
Ray Ni <ray.ni@intel.com>, Laszlo Ersek <lersek@redhat.com>
Subject: [PATCH] UefiCpuPkg/MpInitLib: Skip reading PlatformId on AMD processors.
Date: Fri, 28 Feb 2020 12:45:42 -0600 [thread overview]
Message-ID: <1582915542-28940-2-git-send-email-leo.duran@amd.com> (raw)
In-Reply-To: <1582915542-28940-1-git-send-email-leo.duran@amd.com>
REF: https://bugzilla.tianocore.org/show_bug.cgi?id=2556
This patch uses CPUID signature check to skip reading the PlatformId MSR,
which is not implemented on AMD processors.
The PlatformId is used for loading microcode patches, which is also not
supported and AMD-based platforms. To mitigate the PlatformId dependency,
PcdCpuMicrocodePatchAddress and PcdCpuMMicrodePatchRegionSize must be set
to 0 (default value), in order to bypass microcode loading code paths.
Cc: Eric Dong <eric.dong@intel.com>
Cc: Ray Ni <ray.ni@intel.com>
Cc: Laszlo Ersek <lersek@redhat.com>
Signed-off-by: Leo Duran <leo.duran@amd.com>
---
UefiCpuPkg/Library/MpInitLib/MpLib.c | 34 ++++++++++++++++++++++++++++++++--
1 file changed, 32 insertions(+), 2 deletions(-)
diff --git a/UefiCpuPkg/Library/MpInitLib/MpLib.c b/UefiCpuPkg/Library/MpInitLib/MpLib.c
index d0fbc17..d2200c3 100644
--- a/UefiCpuPkg/Library/MpInitLib/MpLib.c
+++ b/UefiCpuPkg/Library/MpInitLib/MpLib.c
@@ -2,6 +2,8 @@
CPU MP Initialize Library common functions.
Copyright (c) 2016 - 2020, Intel Corporation. All rights reserved.<BR>
+ Copyright (c) 2020, AMD Inc. All rights reserved.<BR>
+
SPDX-License-Identifier: BSD-2-Clause-Patent
**/
@@ -10,6 +12,29 @@
EFI_GUID mCpuInitMpLibHobGuid = CPU_INIT_MP_LIB_HOB_GUID;
+
+/**
+ Determine if the standard CPU signature is "AuthenticAMD".
+
+ @retval TRUE The CPU signature matches.
+ @retval FALSE The CPU signature does not match.
+
+**/
+BOOLEAN
+StandardSignatureIsAuthenticAMD (
+ VOID
+ )
+{
+ UINT32 RegEbx;
+ UINT32 RegEcx;
+ UINT32 RegEdx;
+
+ AsmCpuid (CPUID_SIGNATURE, NULL, &RegEbx, &RegEcx, &RegEdx);
+ return (RegEbx == CPUID_SIGNATURE_AUTHENTIC_AMD_EBX &&
+ RegEcx == CPUID_SIGNATURE_AUTHENTIC_AMD_ECX &&
+ RegEdx == CPUID_SIGNATURE_AUTHENTIC_AMD_EDX);
+}
+
/**
The function will check if BSP Execute Disable is enabled.
@@ -564,8 +589,13 @@ InitializeApData (
CpuMpData->CpuData[ProcessorNumber].Waiting = FALSE;
CpuMpData->CpuData[ProcessorNumber].CpuHealthy = (BistData == 0) ? TRUE : FALSE;
- PlatformIdMsr.Uint64 = AsmReadMsr64 (MSR_IA32_PLATFORM_ID);
- CpuMpData->CpuData[ProcessorNumber].PlatformId = (UINT8) PlatformIdMsr.Bits.PlatformId;
+ //
+ // NOTE: PlatformId is not relevant on AMD platforms.
+ //
+ if (!StandardSignatureIsAuthenticAMD ()) {
+ PlatformIdMsr.Uint64 = AsmReadMsr64 (MSR_IA32_PLATFORM_ID);
+ CpuMpData->CpuData[ProcessorNumber].PlatformId = (UINT8)PlatformIdMsr.Bits.PlatformId;
+ }
AsmCpuid (
CPUID_VERSION_INFO,
--
2.7.4
next prev parent reply other threads:[~2020-02-28 18:46 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-28 18:45 [PATCH v2] UefiCpuPkg: Fix bug in MpInitLib Leo Duran
2020-02-28 18:45 ` Leo Duran [this message]
-- strict thread matches above, loose matches on Subject: below --
2020-02-28 18:58 [PATCH v3] " Leo Duran
2020-02-28 18:58 ` [PATCH] UefiCpuPkg/MpInitLib: Skip reading PlatformId on AMD processors Leo Duran
2020-02-29 7:32 ` Laszlo Ersek
2020-02-29 14:11 ` Ni, Ray
2020-02-29 15:05 [PATCH v4] UefiCpuPkg: Fix bug in MpInitLib Leo Duran
2020-02-29 15:05 ` [PATCH] UefiCpuPkg/MpInitLib: Skip reading PlatformId on AMD processors Leo Duran
2020-02-29 19:50 ` Laszlo Ersek
2020-03-02 1:59 ` Ni, Ray
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