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authorJim Mattson <jmattson@google.com>2024-09-13 10:32:27 -0700
committerBorislav Petkov (AMD) <bp@alien8.de>2024-10-10 10:34:14 +0200
commitff898623af2ed564300752bba83a680a1e4fec8d (patch)
tree6f71a26ae933378b5eabf2548f862685439ede77 /arch/x86
parent8cf0b93919e13d1e8d4466eb4080a4c4d9d66d7b (diff)
x86/cpufeatures: Define X86_FEATURE_AMD_IBPB_RET
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>
Diffstat (limited to 'arch/x86')
-rw-r--r--arch/x86/include/asm/cpufeatures.h3
1 files changed, 2 insertions, 1 deletions
diff --git a/arch/x86/include/asm/cpufeatures.h b/arch/x86/include/asm/cpufeatures.h
index dd4682857c12..a222a24677d7 100644
--- a/arch/x86/include/asm/cpufeatures.h
+++ b/arch/x86/include/asm/cpufeatures.h
@@ -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 */