x86/mmio: Disable KVM mitigation when X86_FEATURE_CLEAR_CPU_BUF is set

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Currently MMIO Stale Data mitigation for CPUs not affected by MDS/TAA is
to only deploy VERW at VMentry by enabling mmio_stale_data_clear static
branch. No mitigation is needed for kernel->user transitions. If such
CPUs are also affected by RFDS, its mitigation may set
X86_FEATURE_CLEAR_CPU_BUF to deploy VERW at kernel->user and VMentry.
This could result in duplicate VERW at VMentry.

Fix this by disabling mmio_stale_data_clear static branch when
X86_FEATURE_CLEAR_CPU_BUF is enabled.

Signed-off-by: Pawan Gupta <pawan.kumar.gupta@linux.intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Dave Hansen <dave.hansen@linux.intel.com>

...

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Pawan Gupta 2024-03-11 12:29:43 -07:00 • committed by Dave Hansen

parent 90d35da658

commit e95df4ec0c

1 changed files with 12 additions and 2 deletions

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arch/x86/kernel/cpu/bugs.c

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