linux/Documentation/admin-guide/hw-vuln
Linus Torvalds 223ba8ee0a Mitigate VMSCAPE issue with indirect branch predictor flushes
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Merge tag 'vmscape-for-linus-20250904' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull vmescape mitigation fixes from Dave Hansen:
 "Mitigate vmscape issue with indirect branch predictor flushes.

  vmscape is a vulnerability that essentially takes Spectre-v2 and
  attacks host userspace from a guest. It particularly affects
  hypervisors like QEMU.

  Even if a hypervisor may not have any sensitive data like disk
  encryption keys, guest-userspace may be able to attack the
  guest-kernel using the hypervisor as a confused deputy.

  There are many ways to mitigate vmscape using the existing Spectre-v2
  defenses like IBRS variants or the IBPB flushes. This series focuses
  solely on IBPB because it works universally across vendors and all
  vulnerable processors. Further work doing vendor and model-specific
  optimizations can build on top of this if needed / wanted.

  Do the normal issue mitigation dance:

   - Add the CPU bug boilerplate

   - Add a list of vulnerable CPUs

   - Use IBPB to flush the branch predictors after running guests"

* tag 'vmscape-for-linus-20250904' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/vmscape: Add old Intel CPUs to affected list
  x86/vmscape: Warn when STIBP is disabled with SMT
  x86/bugs: Move cpu_bugs_smt_update() down
  x86/vmscape: Enable the mitigation
  x86/vmscape: Add conditional IBPB mitigation
  x86/vmscape: Enumerate VMSCAPE bug
  Documentation/hw-vuln: Add VMSCAPE documentation
2025-09-10 20:52:16 -07:00
..
attack_vector_controls.rst x86/bugs: Add attack vector controls for SSB 2025-08-27 18:17:12 +02:00
core-scheduling.rst admin-guide/hw-vuln/core-scheduling: fix return type of PR_SCHED_CORE_GET 2024-04-24 13:04:27 -06:00
cross-thread-rsb.rst Documentation/hw-vuln: Fix rST warning 2023-02-15 07:24:23 -05:00
gather_data_sampling.rst Documentation/x86: Fix backwards on/off logic about YMM support 2023-08-01 15:28:24 -07:00
index.rst Documentation/hw-vuln: Add VMSCAPE documentation 2025-08-14 10:26:03 -07:00
indirect-target-selection.rst Documentation: x86/bugs/its: Add ITS documentation 2025-05-09 13:22:04 -07:00
l1d_flush.rst Documentation: Add L1D flushing Documentation 2021-07-28 11:42:25 +02:00
l1tf.rst
mds.rst docs/hw-vuln: Update desc of best effort mode 2023-10-10 13:35:55 -06:00
multihit.rst
old_microcode.rst x86/cpu: Help users notice when running old Intel microcode 2025-04-22 08:33:52 +02:00
processor_mmio_stale_data.rst x86/bugs: Rename MDS machinery to something more generic 2025-06-16 18:45:18 +02:00
reg-file-data-sampling.rst x86/rfds: Exclude P-only parts from the RFDS affected list 2025-03-19 11:17:23 +01:00
rsb.rst x86/bugs: Add RSB mitigation document 2025-04-09 12:42:09 +02:00
special-register-buffer-data-sampling.rst docs: admin-guide: hw-vuln: avoid using ReST :doc:`foo` markup 2021-06-17 13:24:36 -06:00
spectre.rst x86/bugs: Remove duplicate Spectre cmdline option descriptions 2024-06-28 15:28:38 +02:00
srso.rst x86/bugs: KVM: Add support for SRSO_MSR_FIX 2025-02-26 15:13:06 +01:00
tsx_async_abort.rst docs/hw-vuln: Update desc of best effort mode 2023-10-10 13:35:55 -06:00
vmscape.rst Documentation/hw-vuln: Add VMSCAPE documentation 2025-08-14 10:26:03 -07:00