diff options
| -rw-r--r-- | arch/x86/include/asm/barrier.h | 18 | ||||
| -rw-r--r-- | arch/x86/include/asm/cpufeatures.h | 2 | ||||
| -rw-r--r-- | arch/x86/include/asm/processor.h | 18 | ||||
| -rw-r--r-- | arch/x86/kernel/cpu/amd.c | 3 | ||||
| -rw-r--r-- | arch/x86/kernel/cpu/common.c | 7 | ||||
| -rw-r--r-- | arch/x86/kernel/cpu/hygon.c | 3 |
6 files changed, 32 insertions, 19 deletions
diff --git a/arch/x86/include/asm/barrier.h b/arch/x86/include/asm/barrier.h index 35389b2af88e..0216f63a366b 100644 --- a/arch/x86/include/asm/barrier.h +++ b/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 */ diff --git a/arch/x86/include/asm/cpufeatures.h b/arch/x86/include/asm/cpufeatures.h index 4af140cf5719..3e973ff20e23 100644 --- a/arch/x86/include/asm/cpufeatures.h +++ b/arch/x86/include/asm/cpufeatures.h @@ -308,10 +308,10 @@ #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 */ /* Intel-defined CPU features, CPUID level 0x00000007:1 (EAX), word 12 */ #define X86_FEATURE_AVX_VNNI (12*32+ 4) /* AVX VNNI instructions */ diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h index ae81a7191c1c..26620d7642a9 100644 --- a/arch/x86/include/asm/processor.h +++ b/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 */ diff --git a/arch/x86/kernel/cpu/amd.c b/arch/x86/kernel/cpu/amd.c index f322ebd053a9..2055fb308f5b 100644 --- a/arch/x86/kernel/cpu/amd.c +++ b/arch/x86/kernel/cpu/amd.c @@ -1162,6 +1162,9 @@ static void init_amd(struct cpuinfo_x86 *c) if (!cpu_has(c, X86_FEATURE_HYPERVISOR) && cpu_has_amd_erratum(c, amd_erratum_1485)) msr_set_bit(MSR_ZEN4_BP_CFG, MSR_ZEN4_BP_CFG_SHARED_BTB_FIX_BIT); + + /* AMD CPUs don't need fencing after x2APIC/TSC_DEADLINE MSR writes. */ + clear_cpu_cap(c, X86_FEATURE_APIC_MSRS_FENCE); } #ifdef CONFIG_X86_32 diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c index b14fc8c1c953..98f7ea6b931c 100644 --- a/arch/x86/kernel/cpu/common.c +++ b/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 diff --git a/arch/x86/kernel/cpu/hygon.c b/arch/x86/kernel/cpu/hygon.c index 6f247d66758d..f0cd95502faa 100644 --- a/arch/x86/kernel/cpu/hygon.c +++ b/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) |