Messages in this thread Patch in this message | | | From | Juergen Gross <> | Subject | [PATCH v5 15/16] x86: do MTRR/PAT setup on all secondary CPUs in parallel | Date | Wed, 2 Nov 2022 08:47:12 +0100 |
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Instead of serializing MTRR/PAT setup on the secondary CPUs in order to avoid clobbering of static variables used by the setup process, put those variables into a structure held on the stack and drop the serialization.
This speeds up the start of secondary CPUs a little bit (on a small system with 8 CPUs the time needed for starting the secondary CPUs was measured to go down from about 60 milliseconds without this patch to about 55 milliseconds with this patch applied).
Signed-off-by: Juergen Gross <jgross@suse.com> --- V4: - new patch --- arch/x86/include/asm/cacheinfo.h | 10 ++++++-- arch/x86/include/asm/mtrr.h | 13 +++++----- arch/x86/kernel/cpu/cacheinfo.c | 28 ++++++++------------- arch/x86/kernel/cpu/mtrr/generic.c | 40 ++++++++++++++---------------- 4 files changed, 45 insertions(+), 46 deletions(-)
diff --git a/arch/x86/include/asm/cacheinfo.h b/arch/x86/include/asm/cacheinfo.h index ce9685fc78d8..f66578e1e4e1 100644 --- a/arch/x86/include/asm/cacheinfo.h +++ b/arch/x86/include/asm/cacheinfo.h @@ -10,8 +10,14 @@ extern unsigned int memory_caching_control; void cacheinfo_amd_init_llc_id(struct cpuinfo_x86 *c, int cpu); void cacheinfo_hygon_init_llc_id(struct cpuinfo_x86 *c, int cpu); -void cache_disable(void); -void cache_enable(void); +struct cache_state { + unsigned long cr4; + u32 mtrr_deftype_lo; + u32 mtrr_deftype_hi; +}; + +void cache_disable(struct cache_state *state); +void cache_enable(struct cache_state *state); void set_cache_aps_delayed_init(bool val); bool get_cache_aps_delayed_init(void); void cache_bp_init(void); diff --git a/arch/x86/include/asm/mtrr.h b/arch/x86/include/asm/mtrr.h index f0eeaf6e5f5f..2ea4a9de7318 100644 --- a/arch/x86/include/asm/mtrr.h +++ b/arch/x86/include/asm/mtrr.h @@ -23,6 +23,7 @@ #ifndef _ASM_X86_MTRR_H #define _ASM_X86_MTRR_H +#include <asm/cacheinfo.h> #include <uapi/asm/mtrr.h> /* @@ -44,9 +45,9 @@ extern void mtrr_centaur_report_mcr(int mcr, u32 lo, u32 hi); extern void mtrr_bp_restore(void); extern int mtrr_trim_uncached_memory(unsigned long end_pfn); extern int amd_special_default_mtrr(void); -void mtrr_disable(void); -void mtrr_enable(void); -void mtrr_generic_set_state(void); +void mtrr_disable(struct cache_state *state); +void mtrr_enable(struct cache_state *state); +void mtrr_generic_set_state(struct cache_state *state); # else static inline u8 mtrr_type_lookup(u64 addr, u64 end, u8 *uniform) { @@ -84,9 +85,9 @@ static inline void mtrr_centaur_report_mcr(int mcr, u32 lo, u32 hi) } #define mtrr_bp_init() do {} while (0) #define mtrr_bp_restore() do {} while (0) -#define mtrr_disable() do {} while (0) -#define mtrr_enable() do {} while (0) -#define mtrr_generic_set_state() do {} while (0) +#define mtrr_disable(s) do {} while (0) +#define mtrr_enable(s) do {} while (0) +#define mtrr_generic_set_state(s) do {} while (0) # endif #ifdef CONFIG_COMPAT diff --git a/arch/x86/kernel/cpu/cacheinfo.c b/arch/x86/kernel/cpu/cacheinfo.c index 231cf1ff0641..7e370c979417 100644 --- a/arch/x86/kernel/cpu/cacheinfo.c +++ b/arch/x86/kernel/cpu/cacheinfo.c @@ -1057,10 +1057,7 @@ int populate_cache_leaves(unsigned int cpu) * The caller must ensure that local interrupts are disabled and * are reenabled after cache_enable() has been called. */ -static unsigned long saved_cr4; -static DEFINE_RAW_SPINLOCK(cache_disable_lock); - -void cache_disable(void) __acquires(cache_disable_lock) +void cache_disable(struct cache_state *state) { unsigned long cr0; @@ -1071,8 +1068,6 @@ void cache_disable(void) __acquires(cache_disable_lock) * changes to the way the kernel boots */ - raw_spin_lock(&cache_disable_lock); - /* Enter the no-fill (CD=1, NW=0) cache mode and flush caches. */ cr0 = read_cr0() | X86_CR0_CD; write_cr0(cr0); @@ -1088,8 +1083,8 @@ void cache_disable(void) __acquires(cache_disable_lock) /* Save value of CR4 and clear Page Global Enable (bit 7) */ if (cpu_feature_enabled(X86_FEATURE_PGE)) { - saved_cr4 = __read_cr4(); - __write_cr4(saved_cr4 & ~X86_CR4_PGE); + state->cr4 = __read_cr4(); + __write_cr4(state->cr4 & ~X86_CR4_PGE); } /* Flush all TLBs via a mov %cr3, %reg; mov %reg, %cr3 */ @@ -1097,46 +1092,45 @@ void cache_disable(void) __acquires(cache_disable_lock) flush_tlb_local(); if (cpu_feature_enabled(X86_FEATURE_MTRR)) - mtrr_disable(); + mtrr_disable(state); /* Again, only flush caches if we have to. */ if (!static_cpu_has(X86_FEATURE_SELFSNOOP)) wbinvd(); } -void cache_enable(void) __releases(cache_disable_lock) +void cache_enable(struct cache_state *state) { /* Flush TLBs (no need to flush caches - they are disabled) */ count_vm_tlb_event(NR_TLB_LOCAL_FLUSH_ALL); flush_tlb_local(); if (cpu_feature_enabled(X86_FEATURE_MTRR)) - mtrr_enable(); + mtrr_enable(state); /* Enable caches */ write_cr0(read_cr0() & ~X86_CR0_CD); /* Restore value of CR4 */ if (cpu_feature_enabled(X86_FEATURE_PGE)) - __write_cr4(saved_cr4); - - raw_spin_unlock(&cache_disable_lock); + __write_cr4(state->cr4); } static void cache_cpu_init(void) { unsigned long flags; + struct cache_state state; local_irq_save(flags); - cache_disable(); + cache_disable(&state); if (memory_caching_control & CACHE_MTRR) - mtrr_generic_set_state(); + mtrr_generic_set_state(&state); if (memory_caching_control & CACHE_PAT) pat_cpu_init(); - cache_enable(); + cache_enable(&state); local_irq_restore(flags); } diff --git a/arch/x86/kernel/cpu/mtrr/generic.c b/arch/x86/kernel/cpu/mtrr/generic.c index 2f2485d6657f..cddb440f330d 100644 --- a/arch/x86/kernel/cpu/mtrr/generic.c +++ b/arch/x86/kernel/cpu/mtrr/generic.c @@ -663,18 +663,13 @@ static bool set_mtrr_var_ranges(unsigned int index, struct mtrr_var_range *vr) return changed; } -static u32 deftype_lo, deftype_hi; - /** * set_mtrr_state - Set the MTRR state for this CPU. * - * NOTE: The CPU must already be in a safe state for MTRR changes, including - * measures that only a single CPU can be active in set_mtrr_state() in - * order to not be subject to races for usage of deftype_lo (this is - * accomplished by taking cache_disable_lock). + * NOTE: The CPU must already be in a safe state for MTRR changes. * RETURNS: 0 if no changes made, else a mask indicating what was changed. */ -static unsigned long set_mtrr_state(void) +static unsigned long set_mtrr_state(struct cache_state *state) { unsigned long change_mask = 0; unsigned int i; @@ -691,38 +686,40 @@ static unsigned long set_mtrr_state(void) * Set_mtrr_restore restores the old value of MTRRdefType, * so to set it we fiddle with the saved value: */ - if ((deftype_lo & 0xff) != mtrr_state.def_type - || ((deftype_lo & 0xc00) >> 10) != mtrr_state.enabled) { - - deftype_lo = (deftype_lo & ~0xcff) | mtrr_state.def_type | - (mtrr_state.enabled << 10); + if ((state->mtrr_deftype_lo & 0xff) != mtrr_state.def_type + || ((state->mtrr_deftype_lo & 0xc00) >> 10) != mtrr_state.enabled) { + state->mtrr_deftype_lo = (state->mtrr_deftype_lo & ~0xcff) | + mtrr_state.def_type | + (mtrr_state.enabled << 10); change_mask |= MTRR_CHANGE_MASK_DEFTYPE; } return change_mask; } -void mtrr_disable(void) +void mtrr_disable(struct cache_state *state) { /* Save MTRR state */ - rdmsr(MSR_MTRRdefType, deftype_lo, deftype_hi); + rdmsr(MSR_MTRRdefType, state->mtrr_deftype_lo, state->mtrr_deftype_hi); /* Disable MTRRs, and set the default type to uncached */ - mtrr_wrmsr(MSR_MTRRdefType, deftype_lo & ~0xcff, deftype_hi); + mtrr_wrmsr(MSR_MTRRdefType, state->mtrr_deftype_lo & ~0xcff, + state->mtrr_deftype_hi); } -void mtrr_enable(void) +void mtrr_enable(struct cache_state *state) { /* Intel (P6) standard MTRRs */ - mtrr_wrmsr(MSR_MTRRdefType, deftype_lo, deftype_hi); + mtrr_wrmsr(MSR_MTRRdefType, state->mtrr_deftype_lo, + state->mtrr_deftype_hi); } -void mtrr_generic_set_state(void) +void mtrr_generic_set_state(struct cache_state *state) { unsigned long mask, count; /* Actually set the state */ - mask = set_mtrr_state(); + mask = set_mtrr_state(state); /* Use the atomic bitops to update the global mask */ for (count = 0; count < sizeof(mask) * 8; ++count) { @@ -747,11 +744,12 @@ static void generic_set_mtrr(unsigned int reg, unsigned long base, { unsigned long flags; struct mtrr_var_range *vr; + struct cache_state state; vr = &mtrr_state.var_ranges[reg]; local_irq_save(flags); - cache_disable(); + cache_disable(&state); if (size == 0) { /* @@ -770,7 +768,7 @@ static void generic_set_mtrr(unsigned int reg, unsigned long base, mtrr_wrmsr(MTRRphysMask_MSR(reg), vr->mask_lo, vr->mask_hi); } - cache_enable(); + cache_enable(&state); local_irq_restore(flags); } -- 2.35.3
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