[SRU Focal 0/3] CVE-2022-27672

[Thadeu Lima de Souza Cascardo]

[Impact]
A VM may force the CPU to go to idle and when it gets back from idle, it
could leverage the RSB from a sibling thread to mount a speculative
execution attack.

[Backport]
Simple conflicts and the placement of setting mitigate_smt_rsb.

[Potential regression]
It would affect VMs, specially when dealing with idleness.

Tom Lendacky (3):
  x86/speculation: Identify processors vulnerable to SMT RSB predictions
  KVM: x86: Mitigate the cross-thread return address predictions bug
  Documentation/hw-vuln: Add documentation for Cross-Thread Return
    Predictions

 .../admin-guide/hw-vuln/cross-thread-rsb.rst  | 92 +++++++++++++++++++
 Documentation/admin-guide/hw-vuln/index.rst   |  1 +
 arch/x86/include/asm/cpufeatures.h            |  1 +
 arch/x86/kernel/cpu/common.c                  |  9 +-
 arch/x86/kvm/x86.c                            | 44 ++++++---
 5 files changed, 134 insertions(+), 13 deletions(-)
 create mode 100644 Documentation/admin-guide/hw-vuln/cross-thread-rsb.rst

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2.34.1