[edk2-devel] [PATCH V4 0/7] Introduce CcProbe in MdePkg

[Min Xu]

BZ: https://bugzilla.tianocore.org/show_bug.cgi?id=3902

Bad IO performance in SEC phase is observed after TDX features was
introduced. (after commit b6b2de884864 - "MdePkg: Support mmio for
Tdx guest in BaseIoLibIntrinsic").

This is because IsTdxGuest() will be called in each MMIO operation.
It is trying to cache the result of the probe in the efi data segment.
However, that doesn't work in SEC, because the data segment is read only
(so the write seems to succeed but a read will always return the
original value), leading to us calling TdIsEnabled() check for every
mmio we do, which is causing the slowdown because it's very expensive.

CcProbe is introduced in this patch-set. It is called in
BaseIoLibIntrinsicSev instead of IsTdxGuest. There are 2 versions of
the CcProbeLib. Null instance of CcProbe always returns
CCGuestTypeNonEncrypted. Its OvmfPkg version checks the Ovmf work area
and returns the CC guest type.

In this patch-set another issue is fixed with CcProbe as well. If the
working guest is SEV and in the beginning of SecMain.c TdIsEnabled()
was called. At this point, exception handling is not established and
a CPUID instruction will generate a #VC and cause the booting SEV guest
to crash. Patch #7 is to fix this broken.

Code is at: https://github.com/mxu9/edk2/tree/cc_probe.v4

v4 changes:
 - Rename the field name in CC_GUEST_TYPE from CCXxx to CcXxx based
   on the community feedback.

v3 changes:
 - Fix the broken issue in SEV guest at SecMain.c. Please refer to
   Patch #7.

v2 changes:
 - Rename TdProbe to CcProbe to make the lib work for Confidential
   Computing guests.
 - Rename the GUEST_TYPE to CC_GUEST_TYPE and move it from
   WorkArea.h at OvmfPkg to ConfidentialComputingGuestAttr.h at MdePkg.
   This is because CcProbeLib is designed to return the CC Guest
   type and the lib is located at MdePkg.
 - Rename the CC_GUEST_TYPE's fields name to Camel style. See the
   commit message in patch #1.

Cc: Michael D Kinney <michael.d.kinney at intel.com>
Cc: Liming Gao <gaoliming at byosoft.com.cn>
Cc: Zhiguang Liu <zhiguang.liu at intel.com>
Cc: James Bottomley <jejb at linux.ibm.com>
Cc: Jiewen Yao <jiewen.yao at intel.com>
Cc: Gerd Hoffmann <kraxel at redhat.com>
Cc: Brijesh Singh <brijesh.singh at amd.com>
Cc: Erdem Aktas <erdemaktas at google.com>
Cc: Tom Lendacky <thomas.lendacky at amd.com>
Signed-off-by: Min Xu <min.m.xu at intel.com>

Min Xu (7):
  MdePkg: Add CC_GUEST_TYPE in ConfidentialComputingGuestAttr.h
  OvmfPkg: Replace GUEST_TYPE with CC_GUEST_TYPE
  MdePkg: Add CcProbeLibNull
  OvmfPkg: Add CcProbeLib
  OvmfPkg: Add CcProbeLib in *.dsc
  MdePkg: Probe Cc guest in BaseIoLibIntrinsicSev
  OvmfPkg: Call CcProbe in SecMain.c instead of TsIsEnabled

 .../Include/ConfidentialComputingGuestAttr.h  | 11 ++++++-
 MdePkg/Include/Library/CcProbeLib.h           | 26 ++++++++++++++++
 .../BaseIoLibIntrinsicSev.inf                 |  1 +
 .../BaseIoLibIntrinsic/IoLibInternalTdx.c     | 13 ++------
 .../Library/CcProbeLibNull/CcProbeLibNull.c   | 26 ++++++++++++++++
 .../Library/CcProbeLibNull/CcProbeLibNull.inf | 21 +++++++++++++
 MdePkg/MdePkg.dec                             |  5 +++
 MdePkg/MdePkg.dsc                             |  1 +
 OvmfPkg/AmdSev/AmdSevX64.dsc                  |  1 +
 OvmfPkg/Bhyve/BhyveX64.dsc                    |  1 +
 OvmfPkg/CloudHv/CloudHvX64.dsc                |  1 +
 OvmfPkg/Include/WorkArea.h                    |  9 +-----
 OvmfPkg/IntelTdx/IntelTdxX64.dsc              |  1 +
 OvmfPkg/IntelTdx/Sec/SecMain.c                |  6 ++--
 OvmfPkg/IntelTdx/Sec/SecMain.inf              |  1 +
 .../PeiMemEncryptSevLibInternal.c             |  2 +-
 .../SecMemEncryptSevLibInternal.c             |  2 +-
 OvmfPkg/Library/CcProbeLib/CcProbeLib.c       | 31 +++++++++++++++++++
 OvmfPkg/Library/CcProbeLib/CcProbeLib.inf     | 25 +++++++++++++++
 OvmfPkg/Library/QemuFwCfgLib/QemuFwCfgPei.c   |  2 +-
 OvmfPkg/Microvm/MicrovmX64.dsc                |  1 +
 OvmfPkg/OvmfPkgIa32.dsc                       |  1 +
 OvmfPkg/OvmfPkgIa32X64.dsc                    |  1 +
 OvmfPkg/OvmfPkgX64.dsc                        |  1 +
 OvmfPkg/OvmfXen.dsc                           |  1 +
 OvmfPkg/Sec/AmdSev.c                          |  2 +-
 OvmfPkg/Sec/SecMain.c                         |  5 +--
 OvmfPkg/Sec/SecMain.inf                       |  1 +
 28 files changed, 170 insertions(+), 29 deletions(-)
 create mode 100644 MdePkg/Include/Library/CcProbeLib.h
 create mode 100644 MdePkg/Library/CcProbeLibNull/CcProbeLibNull.c
 create mode 100644 MdePkg/Library/CcProbeLibNull/CcProbeLibNull.inf
 create mode 100644 OvmfPkg/Library/CcProbeLib/CcProbeLib.c
 create mode 100644 OvmfPkg/Library/CcProbeLib/CcProbeLib.inf

-- 
2.29.2.windows.2



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