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* [PATCH v4 00/23] i386: Support CET for KVM
@ 2025-11-18  3:42 Zhao Liu
  2025-11-18  3:42 ` [PATCH v4 01/23] i386/cpu: Clean up indent style of x86_ext_save_areas[] Zhao Liu
                   ` (22 more replies)
  0 siblings, 23 replies; 24+ messages in thread
From: Zhao Liu @ 2025-11-18  3:42 UTC (permalink / raw)
  To: Paolo Bonzini, Marcelo Tosatti
  Cc: qemu-devel, kvm, Chao Gao, Xin Li, John Allen, Babu Moger,
	Mathias Krause, Dapeng Mi, Zide Chen, Xiaoyao Li, Chenyi Qiang,
	Farrah Chen, Zhao Liu

Hi,

This the v4 series to support CET (CET-SHSTK & CET-IBT) in QEMU, which
is based on the master branch at the commit 9febfa94b69b ("Merge tag
'for-upstream' of https://repo.or.cz/qemu/kevin into staging"). And you
can also find the code here:

https://gitlab.com/zhao.liu/qemu/-/tree/i386-all-for-dmr-v1.1-11-17-2025

Compared to v3 [1], v4 mainly considers pl0 SSP MSR for FRED, and fixes
migratable_flags for FEAT_XSAVE_XSS_LO. More details, pls refer Change
Log in the following.

Thanks for your review!

Overview
========

Control-flow enforcement technology includes 2 x86-architectural
features:
 - CET shadow stack (CET-SHSTK or CET-SS).
 - CET indirect branch tracking (CET-IBT).

Intel has implemented both 2 features since Sapphire Rapids (P-core) &
Sierra Forest (E-core).

AMD also implemented shadow stack since Zen3 [2] - this series has
considerred only-shstk case and is supposed to work on AMD platform, but
I hasn't tested this on AMD.

The basic CET support (patch 12-20) includes:
 * CET-S & CET-U supervisor xstates support.
 * CET CPUIDs enumeration.
 * CET MSRs save & load.
 * CET guest SSP register (KVM treats this as a special internal
   register - KVM_REG_GUEST_SSP) save & load.
 * Vmstates for MSRs & guest SSP.

But before CET support, there's a lot of cleanup work needed for
supervisor xstate.

Before CET-S/CET-U, QEMU has already supports arch lbr as the 1st
supervisor xstate. Although arch LBR has not yet been merged into KVM
(still planned), this series cleans up supervisor state-related support
and avoids breaking the current arch LBR in QEMU - that's what patch
2-11 are doing.

Additionally, besides KVM, this series also supports CET for TDX.

Change Log
==========

Changes Since v3:
 - Fill CPUID 0xD subleaves from KVM CPUID instead of host CPUID for
   non-dynamic xstates (i.e., except AMX xstates for now).
 - Save/restore/migrate MSR_IA32_PL0_SSP for FRED.
 - Fix migratable_flags for FEAT_XSAVE_XSS_LO.
 - Refine commit message for CET TDX support.

[1]: https://lore.kernel.org/qemu-devel/20251024065632.1448606-1-zhao1.liu@intel.com/
[2]: https://lore.kernel.org/all/20250908201750.98824-1-john.allen@amd.com/

Thanks and Best Regards,
Zhao
---
Chao Gao (1):
  i386/cpu: Fix supervisor xstate initialization

Chenyi Qiang (1):
  i386/tdx: Add CET SHSTK/IBT into the supported CPUID by XFAM

Xin Li (Intel) (2):
  i386/cpu: Save/restore SSP0 MSR for FRED
  i386/cpu: Migrate MSR_IA32_PL0_SSP for FRED and CET-SHSTK

Yang Weijiang (5):
  i386/cpu: Enable xsave support for CET states
  i386/kvm: Add save/restore support for CET MSRs
  i386/kvm: Add save/restore support for KVM_REG_GUEST_SSP
  i386/machine: Add vmstate for cet-shstk and cet-ibt
  i386/cpu: Advertise CET related flags in feature words

Zhao Liu (14):
  i386/cpu: Clean up indent style of x86_ext_save_areas[]
  i386/cpu: Clean up arch lbr xsave struct and comment
  i386/cpu: Reorganize arch lbr structure definitions
  i386/cpu: Make ExtSaveArea store an array of dependencies
  i386/cpu: Add avx10 dependency for Opmask/ZMM_Hi256/Hi16_ZMM
  i386/kvm: Initialize x86_ext_save_areas[] based on KVM support
  i386/cpu: Use x86_ext_save_areas[] for CPUID.0XD subleaves
  i386/cpu: Reorganize dependency check for arch lbr state
  i386/cpu: Drop pmu check in CPUID 0x1C encoding
  i386/cpu: Add missing migratable xsave features
  i386/cpu: Add CET support in CR4
  i386/cpu: Mark cet-u & cet-s xstates as migratable
  i386/cpu: Enable cet-ss & cet-ibt for supported CPU models
  i386/tdx: Fix missing spaces in tdx_xfam_deps[]

 target/i386/cpu.c         | 256 +++++++++++++++++++++++++++-----------
 target/i386/cpu.h         | 110 ++++++++++++----
 target/i386/helper.c      |  12 ++
 target/i386/kvm/kvm-cpu.c |  23 +++-
 target/i386/kvm/kvm.c     | 117 +++++++++++++++++
 target/i386/kvm/tdx.c     |  20 +--
 target/i386/machine.c     |  78 ++++++++++++
 7 files changed, 501 insertions(+), 115 deletions(-)

-- 
2.34.1



^ permalink raw reply	[flat|nested] 24+ messages in thread

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-- links below jump to the message on this page --
2025-11-18  3:42 [PATCH v4 00/23] i386: Support CET for KVM Zhao Liu
2025-11-18  3:42 ` [PATCH v4 01/23] i386/cpu: Clean up indent style of x86_ext_save_areas[] Zhao Liu
2025-11-18  3:42 ` [PATCH v4 02/23] i386/cpu: Clean up arch lbr xsave struct and comment Zhao Liu
2025-11-18  3:42 ` [PATCH v4 03/23] i386/cpu: Reorganize arch lbr structure definitions Zhao Liu
2025-11-18  3:42 ` [PATCH v4 04/23] i386/cpu: Make ExtSaveArea store an array of dependencies Zhao Liu
2025-11-18  3:42 ` [PATCH v4 05/23] i386/cpu: Add avx10 dependency for Opmask/ZMM_Hi256/Hi16_ZMM Zhao Liu
2025-11-18  3:42 ` [PATCH v4 06/23] i386/kvm: Initialize x86_ext_save_areas[] based on KVM support Zhao Liu
2025-11-18  3:42 ` [PATCH v4 07/23] i386/cpu: Use x86_ext_save_areas[] for CPUID.0XD subleaves Zhao Liu
2025-11-18  3:42 ` [PATCH v4 08/23] i386/cpu: Reorganize dependency check for arch lbr state Zhao Liu
2025-11-18  3:42 ` [PATCH v4 09/23] i386/cpu: Drop pmu check in CPUID 0x1C encoding Zhao Liu
2025-11-18  3:42 ` [PATCH v4 10/23] i386/cpu: Fix supervisor xstate initialization Zhao Liu
2025-11-18  3:42 ` [PATCH v4 11/23] i386/cpu: Add missing migratable xsave features Zhao Liu
2025-11-18  3:42 ` [PATCH v4 12/23] i386/cpu: Enable xsave support for CET states Zhao Liu
2025-11-18  3:42 ` [PATCH v4 13/23] i386/cpu: Add CET support in CR4 Zhao Liu
2025-11-18  3:42 ` [PATCH v4 14/23] i386/cpu: Save/restore SSP0 MSR for FRED Zhao Liu
2025-11-18  3:42 ` [PATCH v4 15/23] i386/kvm: Add save/restore support for CET MSRs Zhao Liu
2025-11-18  3:42 ` [PATCH v4 16/23] i386/kvm: Add save/restore support for KVM_REG_GUEST_SSP Zhao Liu
2025-11-18  3:42 ` [PATCH v4 17/23] i386/cpu: Migrate MSR_IA32_PL0_SSP for FRED and CET-SHSTK Zhao Liu
2025-11-18  3:42 ` [PATCH v4 18/23] i386/machine: Add vmstate for cet-shstk and cet-ibt Zhao Liu
2025-11-18  3:42 ` [PATCH v4 19/23] i386/cpu: Mark cet-u & cet-s xstates as migratable Zhao Liu
2025-11-18  3:42 ` [PATCH v4 20/23] i386/cpu: Advertise CET related flags in feature words Zhao Liu
2025-11-18  3:42 ` [PATCH v4 21/23] i386/cpu: Enable cet-ss & cet-ibt for supported CPU models Zhao Liu
2025-11-18  3:42 ` [PATCH v4 22/23] i386/tdx: Fix missing spaces in tdx_xfam_deps[] Zhao Liu
2025-11-18  3:42 ` [PATCH v4 23/23] i386/tdx: Add CET SHSTK/IBT into the supported CPUID by XFAM Zhao Liu

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