[PATCH v3 00/20] i386: Support CET for KVM

[Zhao Liu <zhao1.liu@intel.com>]

Hi,

This the v3 series to support CET (CET-SHSTK & CET-IBT) in QEMU, which
is based on the commit c0e80879c876 ("Merge tag 'pull-vfio-20251022' of
https://github.com/legoater/qemu into staging"). And you can also find
the code here:

https://gitlab.com/zhao.liu/qemu/-/commits/i386-cet-v1-10-22-2025

Compared to v2 [1] (posted two years ago), the basic CET support (
xstate/MSR/vmstate/CPUID) remains roughly unchanged. And I also noted
the change logs in the patches inherited from v2.

Thanks for your feedback!

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 11-17) 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
2-10 are doing.

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

[1]: https://lore.kernel.org/qemu-devel/20230720111445.99509-1-weijiang.yang@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

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

Zhao Liu (13):
  linux-headers: Update to v6.18-rc2
  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/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[]

 include/standard-headers/linux/ethtool.h      |   1 +
 include/standard-headers/linux/fuse.h         |  22 +-
 .../linux/input-event-codes.h                 |   1 +
 include/standard-headers/linux/input.h        |  22 +-
 include/standard-headers/linux/pci_regs.h     |  10 +
 include/standard-headers/linux/virtio_ids.h   |   1 +
 include/standard-headers/linux/virtio_rtc.h   | 237 ++++++++++++++++++
 include/standard-headers/linux/virtio_spi.h   | 181 +++++++++++++
 linux-headers/asm-loongarch/kvm.h             |   1 +
 linux-headers/asm-riscv/kvm.h                 |  23 +-
 linux-headers/asm-riscv/ptrace.h              |   4 +-
 linux-headers/asm-x86/kvm.h                   |  34 +++
 linux-headers/asm-x86/unistd_64.h             |   1 +
 linux-headers/asm-x86/unistd_x32.h            |   1 +
 linux-headers/linux/kvm.h                     |   3 +
 linux-headers/linux/psp-sev.h                 |  10 +-
 linux-headers/linux/stddef.h                  |   1 -
 linux-headers/linux/vduse.h                   |   2 +-
 linux-headers/linux/vhost.h                   |   4 +-
 target/i386/cpu.c                             | 227 ++++++++++++-----
 target/i386/cpu.h                             |  99 ++++++--
 target/i386/helper.c                          |  12 +
 target/i386/kvm/kvm.c                         | 103 ++++++++
 target/i386/kvm/tdx.c                         |  20 +-
 target/i386/machine.c                         |  53 ++++
 25 files changed, 968 insertions(+), 105 deletions(-)
 create mode 100644 include/standard-headers/linux/virtio_rtc.h
 create mode 100644 include/standard-headers/linux/virtio_spi.h

-- 
2.34.1