@@ -207,6 +207,7 @@
#define X86_FEATURE_RETPOLINE_AMD ( 7*32+13) /* AMD Retpoline mitigation for Spectre variant 2 */
#define X86_FEATURE_INTEL_PPIN ( 7*32+14) /* Intel Processor Inventory Number */
+#define X86_FEATURE_IBPB ( 7*32+16) /* Using Indirect Branch Prediction Barrier */
#define X86_FEATURE_AMD_PRED_CMD ( 7*32+17) /* Prediction Command MSR (AMD) */
#define X86_FEATURE_MBA ( 7*32+18) /* Memory Bandwidth Allocation */
#define X86_FEATURE_RSB_CTXSW ( 7*32+19) /* Fill RSB on context switches */
@@ -218,5 +218,21 @@ static inline void vmexit_fill_RSB(void)
#endif
}
+static inline void indirect_branch_prediction_barrier(void)
+{
+ unsigned long ax, cx, dx;
+
+ asm volatile(ALTERNATIVE("",
+ "movl %[msr], %%ecx\n\t"
+ "movl %[val], %%eax\n\t"
+ "movl $0, %%edx\n\t"
+ "wrmsr",
+ X86_FEATURE_IBPB)
+ : "=a" (ax), "=c" (cx), "=d" (dx)
+ : [msr] "i" (MSR_IA32_PRED_CMD),
+ [val] "i" (PRED_CMD_IBPB)
+ : "memory");
+}
+
#endif /* __ASSEMBLY__ */
#endif /* __NOSPEC_BRANCH_H__ */
@@ -249,6 +249,13 @@ static void __init spectre_v2_select_mitigation(void)
setup_force_cpu_cap(X86_FEATURE_RSB_CTXSW);
pr_info("Filling RSB on context switch\n");
}
+
+ /* Initialize Indirect Branch Prediction Barrier if supported */
+ if (boot_cpu_has(X86_FEATURE_SPEC_CTRL) ||
+ boot_cpu_has(X86_FEATURE_AMD_PRED_CMD)) {
+ setup_force_cpu_cap(X86_FEATURE_IBPB);
+ pr_info("Enabling Indirect Branch Prediction Barrier\n");
+ }
}
#undef pr_fmt