x86/CPU/AMD: Add CPUID faulting support

Add CPUID faulting support on AMD using the same user interface.

Signed-off-by: Borislav Petkov (AMD) <[email protected]>
Reviewed-by: Thomas Gleixner <[email protected]>
Link: https://lore.kernel.org/[email protected]

Author: bp3tk0v

arch/x86/include/asm/cpufeatures.h

@@ -457,9 +457,12 @@
 #define X86_FEATURE_WRMSR_XX_BASE_NS	(20*32+ 1) /* WRMSR to {FS,GS,KERNEL_GS}_BASE is non-serializing */
 #define X86_FEATURE_LFENCE_RDTSC	(20*32+ 2) /* LFENCE always serializing / synchronizes RDTSC */
 #define X86_FEATURE_NULL_SEL_CLR_BASE	(20*32+ 6) /* Null Selector Clears Base */
+
 #define X86_FEATURE_AUTOIBRS		(20*32+ 8) /* Automatic IBRS */
 #define X86_FEATURE_NO_SMM_CTL_MSR	(20*32+ 9) /* SMM_CTL MSR is not present */
 
+#define X86_FEATURE_GP_ON_USER_CPUID	(20*32+17) /* User CPUID faulting */
+
 #define X86_FEATURE_PREFETCHI		(20*32+20) /* Prefetch Data/Instruction to Cache Level */
 #define X86_FEATURE_SBPB		(20*32+27) /* Selective Branch Prediction Barrier */
 #define X86_FEATURE_IBPB_BRTYPE		(20*32+28) /* MSR_PRED_CMD[IBPB] flushes all branch type predictions */

arch/x86/include/asm/msr-index.h

@@ -830,6 +830,7 @@
 #define MSR_K7_HWCR_SMMLOCK		BIT_ULL(MSR_K7_HWCR_SMMLOCK_BIT)
 #define MSR_K7_HWCR_IRPERF_EN_BIT	30
 #define MSR_K7_HWCR_IRPERF_EN		BIT_ULL(MSR_K7_HWCR_IRPERF_EN_BIT)
+#define MSR_K7_HWCR_CPUID_USER_DIS_BIT	35
 #define MSR_K7_FID_VID_CTL		0xc0010041
 #define MSR_K7_FID_VID_STATUS		0xc0010042
 #define MSR_K7_HWCR_CPB_DIS_BIT		25

arch/x86/kernel/cpu/amd.c

@@ -489,6 +489,10 @@ static void bsp_init_amd(struct cpuinfo_x86 *c)
 	}
 
 	bsp_determine_snp(c);
+
+	if (cpu_has(c, X86_FEATURE_GP_ON_USER_CPUID))
+		setup_force_cpu_cap(X86_FEATURE_CPUID_FAULT);
+
 	return;
 
 warn:

arch/x86/kernel/process.c

@@ -334,13 +334,21 @@ DEFINE_PER_CPU(u64, msr_misc_features_shadow);
 
 static void set_cpuid_faulting(bool on)
 {
-	u64 msrval;
 
-	msrval = this_cpu_read(msr_misc_features_shadow);
-	msrval &= ~MSR_MISC_FEATURES_ENABLES_CPUID_FAULT;
-	msrval |= (on << MSR_MISC_FEATURES_ENABLES_CPUID_FAULT_BIT);
-	this_cpu_write(msr_misc_features_shadow, msrval);
-	wrmsrq(MSR_MISC_FEATURES_ENABLES, msrval);
+	if (boot_cpu_data.x86_vendor == X86_VENDOR_INTEL) {
+		u64 msrval;
+
+		msrval = this_cpu_read(msr_misc_features_shadow);
+		msrval &= ~MSR_MISC_FEATURES_ENABLES_CPUID_FAULT;
+		msrval |= (on << MSR_MISC_FEATURES_ENABLES_CPUID_FAULT_BIT);
+		this_cpu_write(msr_misc_features_shadow, msrval);
+		wrmsrq(MSR_MISC_FEATURES_ENABLES, msrval);
+	} else if (boot_cpu_data.x86_vendor == X86_VENDOR_AMD) {
+		if (on)
+			msr_set_bit(MSR_K7_HWCR, MSR_K7_HWCR_CPUID_USER_DIS_BIT);
+		else
+			msr_clear_bit(MSR_K7_HWCR, MSR_K7_HWCR_CPUID_USER_DIS_BIT);
+	}
 }
 
 static void disable_cpuid(void)