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x86/cpufeatures: Define X86_FEATURE_AMD_IBPB_RET

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AMD's initial implementation of IBPB did not clear the return address
predictor. Beginning with Zen4, AMD's IBPB *does* clear the return address
predictor. This behavior is enumerated by CPUID.80000008H:EBX.IBPB_RET[30].

Define X86_FEATURE_AMD_IBPB_RET for use in KVM_GET_SUPPORTED_CPUID,
when determining cross-vendor capabilities.

Suggested-by: Venkatesh Srinivas <venkateshs@chromium.org>
Signed-off-by: Jim Mattson <jmattson@google.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Tom Lendacky <thomas.lendacky@amd.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Cc: <stable@kernel.org>
This commit is contained in:
Jim Mattson 2024-09-13 10:32:27 -07:00 committed by Borislav Petkov (AMD)
parent 8cf0b93919
commit ff898623af
1 changed files with 2 additions and 1 deletions
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3
arch/x86/include/asm/cpufeatures.h
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@ -215,7 +215,7 @@
#define X86_FEATURE_SPEC_STORE_BYPASS_DISABLE ( 7*32+23) /* Disable Speculative Store Bypass. */
#define X86_FEATURE_LS_CFG_SSBD ( 7*32+24) /* AMD SSBD implementation via LS_CFG MSR */
#define X86_FEATURE_IBRS ( 7*32+25) /* "ibrs" Indirect Branch Restricted Speculation */
#define X86_FEATURE_IBPB ( 7*32+26) /* "ibpb" Indirect Branch Prediction Barrier */
#define X86_FEATURE_IBPB ( 7*32+26) /* "ibpb" Indirect Branch Prediction Barrier without a guaranteed RSB flush */
#define X86_FEATURE_STIBP ( 7*32+27) /* "stibp" Single Thread Indirect Branch Predictors */
#define X86_FEATURE_ZEN ( 7*32+28) /* Generic flag for all Zen and newer */
#define X86_FEATURE_L1TF_PTEINV ( 7*32+29) /* L1TF workaround PTE inversion */
@ -348,6 +348,7 @@
#define X86_FEATURE_CPPC (13*32+27) /* "cppc" Collaborative Processor Performance Control */
#define X86_FEATURE_AMD_PSFD (13*32+28) /* Predictive Store Forwarding Disable */
#define X86_FEATURE_BTC_NO (13*32+29) /* Not vulnerable to Branch Type Confusion */
#define X86_FEATURE_AMD_IBPB_RET (13*32+30) /* IBPB clears return address predictor */
#define X86_FEATURE_BRS (13*32+31) /* "brs" Branch Sampling available */
/* Thermal and Power Management Leaf, CPUID level 0x00000006 (EAX), word 14 */