Merge tag 'x86_cpu_for_v6.8' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull x86 cpu feature updates from Borislav Petkov:

 - Add synthetic X86_FEATURE flags for the different AMD Zen generations
   and use them everywhere instead of ad-hoc family/model checks. Drop
   an ancient AMD errata checking facility as a result

 - Fix a fragile initcall ordering in intel_epb

 - Do not issue the MFENCE+LFENCE barrier for the TSC deadline and
   X2APIC MSRs on AMD as it is not needed there

* tag 'x86_cpu_for_v6.8' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/CPU/AMD: Add X86_FEATURE_ZEN1
  x86/CPU/AMD: Drop now unused CPU erratum checking function
  x86/CPU/AMD: Get rid of amd_erratum_1485[]
  x86/CPU/AMD: Get rid of amd_erratum_400[]
  x86/CPU/AMD: Get rid of amd_erratum_383[]
  x86/CPU/AMD: Get rid of amd_erratum_1054[]
  x86/CPU/AMD: Move the DIV0 bug detection to the Zen1 init function
  x86/CPU/AMD: Move Zenbleed check to the Zen2 init function
  x86/CPU/AMD: Rename init_amd_zn() to init_amd_zen_common()
  x86/CPU/AMD: Call the spectral chicken in the Zen2 init function
  x86/CPU/AMD: Move erratum 1076 fix into the Zen1 init function
  x86/CPU/AMD: Move the Zen3 BTC_NO detection to the Zen3 init function
  x86/CPU/AMD: Carve out the erratum 1386 fix
  x86/CPU/AMD: Add ZenX generations flags
  x86/cpu/intel_epb: Don't rely on link order
  x86/barrier: Do not serialize MSR accesses on AMD

arch/x86/include/asm/barrier.h

@@ -81,22 +81,4 @@ do {									\
 
 #include <asm-generic/barrier.h>
 
-/*
- * Make previous memory operations globally visible before
- * a WRMSR.
- *
- * MFENCE makes writes visible, but only affects load/store
- * instructions.  WRMSR is unfortunately not a load/store
- * instruction and is unaffected by MFENCE.  The LFENCE ensures
- * that the WRMSR is not reordered.
- *
- * Most WRMSRs are full serializing instructions themselves and
- * do not require this barrier.  This is only required for the
- * IA32_TSC_DEADLINE and X2APIC MSRs.
- */
-static inline void weak_wrmsr_fence(void)
-{
-	asm volatile("mfence; lfence" : : : "memory");
-}
-
 #endif /* _ASM_X86_BARRIER_H */

arch/x86/include/asm/cpufeatures.h

@@ -218,7 +218,7 @@
 #define X86_FEATURE_IBRS		( 7*32+25) /* Indirect Branch Restricted Speculation */
 #define X86_FEATURE_IBPB		( 7*32+26) /* Indirect Branch Prediction Barrier */
 #define X86_FEATURE_STIBP		( 7*32+27) /* Single Thread Indirect Branch Predictors */
-#define X86_FEATURE_ZEN			(7*32+28) /* "" CPU based on Zen microarchitecture */
+#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 */
 #define X86_FEATURE_IBRS_ENHANCED	( 7*32+30) /* Enhanced IBRS */
 #define X86_FEATURE_MSR_IA32_FEAT_CTL	( 7*32+31) /* "" MSR IA32_FEAT_CTL configured */
@@ -308,10 +308,14 @@
 #define X86_FEATURE_SMBA		(11*32+21) /* "" Slow Memory Bandwidth Allocation */
 #define X86_FEATURE_BMEC		(11*32+22) /* "" Bandwidth Monitoring Event Configuration */
 #define X86_FEATURE_USER_SHSTK		(11*32+23) /* Shadow stack support for user mode applications */
-
 #define X86_FEATURE_SRSO		(11*32+24) /* "" AMD BTB untrain RETs */
 #define X86_FEATURE_SRSO_ALIAS		(11*32+25) /* "" AMD BTB untrain RETs through aliasing */
 #define X86_FEATURE_IBPB_ON_VMEXIT	(11*32+26) /* "" Issue an IBPB only on VMEXIT */
+#define X86_FEATURE_APIC_MSRS_FENCE	(11*32+27) /* "" IA32_TSC_DEADLINE and X2APIC MSRs need fencing */
+#define X86_FEATURE_ZEN2		(11*32+28) /* "" CPU based on Zen2 microarchitecture */
+#define X86_FEATURE_ZEN3		(11*32+29) /* "" CPU based on Zen3 microarchitecture */
+#define X86_FEATURE_ZEN4		(11*32+30) /* "" CPU based on Zen4 microarchitecture */
+#define X86_FEATURE_ZEN1		(11*32+31) /* "" CPU based on Zen1 microarchitecture */
 
 /* Intel-defined CPU features, CPUID level 0x00000007:1 (EAX), word 12 */
 #define X86_FEATURE_AVX_VNNI		(12*32+ 4) /* AVX VNNI instructions */

arch/x86/include/asm/processor.h

@@ -749,4 +749,22 @@ enum mds_mitigations {
 
 extern bool gds_ucode_mitigated(void);
 
+/*
+ * Make previous memory operations globally visible before
+ * a WRMSR.
+ *
+ * MFENCE makes writes visible, but only affects load/store
+ * instructions.  WRMSR is unfortunately not a load/store
+ * instruction and is unaffected by MFENCE.  The LFENCE ensures
+ * that the WRMSR is not reordered.
+ *
+ * Most WRMSRs are full serializing instructions themselves and
+ * do not require this barrier.  This is only required for the
+ * IA32_TSC_DEADLINE and X2APIC MSRs.
+ */
+static inline void weak_wrmsr_fence(void)
+{
+	alternative("mfence; lfence", "", ALT_NOT(X86_FEATURE_APIC_MSRS_FENCE));
+}
+
 #endif /* _ASM_X86_PROCESSOR_H */

arch/x86/kernel/cpu/common.c

@@ -1856,6 +1856,13 @@ static void identify_cpu(struct cpuinfo_x86 *c)
 	c->topo.apicid = apic->phys_pkg_id(c->topo.initial_apicid, 0);
 #endif
 
+
+	/*
+	 * Set default APIC and TSC_DEADLINE MSR fencing flag. AMD and
+	 * Hygon will clear it in ->c_init() below.
+	 */
+	set_cpu_cap(c, X86_FEATURE_APIC_MSRS_FENCE);
+
 	/*
 	 * Vendor-specific initialization.  In this section we
 	 * canonicalize the feature flags, meaning if there are

arch/x86/kernel/cpu/hygon.c

@@ -354,6 +354,9 @@ static void init_hygon(struct cpuinfo_x86 *c)
 		set_cpu_bug(c, X86_BUG_SYSRET_SS_ATTRS);
 
 	check_null_seg_clears_base(c);
+
+	/* Hygon CPUs don't need fencing after x2APIC/TSC_DEADLINE MSR writes. */
+	clear_cpu_cap(c, X86_FEATURE_APIC_MSRS_FENCE);
 }
 
 static void cpu_detect_tlb_hygon(struct cpuinfo_x86 *c)

arch/x86/kernel/cpu/intel_epb.c

@@ -237,4 +237,4 @@ static __init int intel_epb_init(void)
 	cpuhp_remove_state(CPUHP_AP_X86_INTEL_EPB_ONLINE);
 	return ret;
 }
-subsys_initcall(intel_epb_init);
+late_initcall(intel_epb_init);

tools/arch/x86/include/asm/cpufeatures.h

@@ -218,7 +218,7 @@
 #define X86_FEATURE_IBRS		( 7*32+25) /* Indirect Branch Restricted Speculation */
 #define X86_FEATURE_IBPB		( 7*32+26) /* Indirect Branch Prediction Barrier */
 #define X86_FEATURE_STIBP		( 7*32+27) /* Single Thread Indirect Branch Predictors */
-#define X86_FEATURE_ZEN			(7*32+28) /* "" CPU based on Zen microarchitecture */
+#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 */
 #define X86_FEATURE_IBRS_ENHANCED	( 7*32+30) /* Enhanced IBRS */
 #define X86_FEATURE_MSR_IA32_FEAT_CTL	( 7*32+31) /* "" MSR IA32_FEAT_CTL configured */