public inbox for devel@edk2.groups.io
 help / color / mirror / Atom feed
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


  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

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-list from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=1582915542-28940-2-git-send-email-leo.duran@amd.com \
    --to=devel@edk2.groups.io \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox