Pawan Gupta a75bf27fe4 x86/its: Add support for ITS-safe return thunk ...

RETs in the lower half of cacheline may be affected by ITS bug,
specifically when the RSB-underflows. Use ITS-safe return thunk for such
RETs.

RETs that are not patched:

- RET in retpoline sequence does not need to be patched, because the
  sequence itself fills an RSB before RET.
- RET in Call Depth Tracking (CDT) thunks __x86_indirect_{call|jump}_thunk
  and call_depth_return_thunk are not patched because CDT by design
  prevents RSB-underflow.
- RETs in .init section are not reachable after init.
- RETs that are explicitly marked safe with ANNOTATE_UNRET_SAFE.

Signed-off-by: Pawan Gupta <pawan.kumar.gupta@linux.intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Josh Poimboeuf <jpoimboe@kernel.org>
Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com>

2025-05-09 13:22:05 -07:00

..

asm

x86/its: Add support for ITS-safe return thunk

2025-05-09 13:22:05 -07:00

uapi/asm

Merge tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm

2025-03-25 14:22:07 -07:00