diff options
Diffstat (limited to 'arch/x86/include/asm/tlbflush.h')
| -rw-r--r-- | arch/x86/include/asm/tlbflush.h | 123 |
1 files changed, 116 insertions, 7 deletions
diff --git a/arch/x86/include/asm/tlbflush.h b/arch/x86/include/asm/tlbflush.h index 50ea3482e1d1..509046cfa5ce 100644 --- a/arch/x86/include/asm/tlbflush.h +++ b/arch/x86/include/asm/tlbflush.h @@ -1,3 +1,4 @@ +/* SPDX-License-Identifier: GPL-2.0 */ #ifndef _ASM_X86_TLBFLUSH_H #define _ASM_X86_TLBFLUSH_H @@ -57,6 +58,23 @@ static inline void invpcid_flush_all_nonglobals(void) __invpcid(0, 0, INVPCID_TYPE_ALL_NON_GLOBAL); } +static inline u64 inc_mm_tlb_gen(struct mm_struct *mm) +{ + u64 new_tlb_gen; + + /* + * Bump the generation count. This also serves as a full barrier + * that synchronizes with switch_mm(): callers are required to order + * their read of mm_cpumask after their writes to the paging + * structures. + */ + smp_mb__before_atomic(); + new_tlb_gen = atomic64_inc_return(&mm->context.tlb_gen); + smp_mb__after_atomic(); + + return new_tlb_gen; +} + #ifdef CONFIG_PARAVIRT #include <asm/paravirt.h> #else @@ -65,6 +83,33 @@ static inline void invpcid_flush_all_nonglobals(void) #define __flush_tlb_single(addr) __native_flush_tlb_single(addr) #endif +static inline bool tlb_defer_switch_to_init_mm(void) +{ + /* + * If we have PCID, then switching to init_mm is reasonably + * fast. If we don't have PCID, then switching to init_mm is + * quite slow, so we try to defer it in the hopes that we can + * avoid it entirely. The latter approach runs the risk of + * receiving otherwise unnecessary IPIs. + * + * This choice is just a heuristic. The tlb code can handle this + * function returning true or false regardless of whether we have + * PCID. + */ + return !static_cpu_has(X86_FEATURE_PCID); +} + +/* + * 6 because 6 should be plenty and struct tlb_state will fit in + * two cache lines. + */ +#define TLB_NR_DYN_ASIDS 6 + +struct tlb_context { + u64 ctx_id; + u64 tlb_gen; +}; + struct tlb_state { /* * cpu_tlbstate.loaded_mm should match CR3 whenever interrupts @@ -73,13 +118,52 @@ struct tlb_state { * mode even if we've already switched back to swapper_pg_dir. */ struct mm_struct *loaded_mm; - int state; + u16 loaded_mm_asid; + u16 next_asid; + + /* + * We can be in one of several states: + * + * - Actively using an mm. Our CPU's bit will be set in + * mm_cpumask(loaded_mm) and is_lazy == false; + * + * - Not using a real mm. loaded_mm == &init_mm. Our CPU's bit + * will not be set in mm_cpumask(&init_mm) and is_lazy == false. + * + * - Lazily using a real mm. loaded_mm != &init_mm, our bit + * is set in mm_cpumask(loaded_mm), but is_lazy == true. + * We're heuristically guessing that the CR3 load we + * skipped more than makes up for the overhead added by + * lazy mode. + */ + bool is_lazy; /* * Access to this CR4 shadow and to H/W CR4 is protected by * disabling interrupts when modifying either one. */ unsigned long cr4; + + /* + * This is a list of all contexts that might exist in the TLB. + * There is one per ASID that we use, and the ASID (what the + * CPU calls PCID) is the index into ctxts. + * + * For each context, ctx_id indicates which mm the TLB's user + * entries came from. As an invariant, the TLB will never + * contain entries that are out-of-date as when that mm reached + * the tlb_gen in the list. + * + * To be clear, this means that it's legal for the TLB code to + * flush the TLB without updating tlb_gen. This can happen + * (for now, at least) due to paravirt remote flushes. + * + * NB: context 0 is a bit special, since it's also used by + * various bits of init code. This is fine -- code that + * isn't aware of PCID will end up harmlessly flushing + * context 0. + */ + struct tlb_context ctxs[TLB_NR_DYN_ASIDS]; }; DECLARE_PER_CPU_SHARED_ALIGNED(struct tlb_state, cpu_tlbstate); @@ -148,6 +232,8 @@ static inline void cr4_set_bits_and_update_boot(unsigned long mask) cr4_set_bits(mask); } +extern void initialize_tlbstate_and_flush(void); + static inline void __native_flush_tlb(void) { /* @@ -207,6 +293,14 @@ static inline void __flush_tlb_all(void) __flush_tlb_global(); else __flush_tlb(); + + /* + * Note: if we somehow had PCID but not PGE, then this wouldn't work -- + * we'd end up flushing kernel translations for the current ASID but + * we might fail to flush kernel translations for other cached ASIDs. + * + * To avoid this issue, we force PCID off if PGE is off. + */ } static inline void __flush_tlb_one(unsigned long addr) @@ -231,9 +325,26 @@ static inline void __flush_tlb_one(unsigned long addr) * and page-granular flushes are available only on i486 and up. */ struct flush_tlb_info { - struct mm_struct *mm; - unsigned long start; - unsigned long end; + /* + * We support several kinds of flushes. + * + * - Fully flush a single mm. .mm will be set, .end will be + * TLB_FLUSH_ALL, and .new_tlb_gen will be the tlb_gen to + * which the IPI sender is trying to catch us up. + * + * - Partially flush a single mm. .mm will be set, .start and + * .end will indicate the range, and .new_tlb_gen will be set + * such that the changes between generation .new_tlb_gen-1 and + * .new_tlb_gen are entirely contained in the indicated range. + * + * - Fully flush all mms whose tlb_gens have been updated. .mm + * will be NULL, .end will be TLB_FLUSH_ALL, and .new_tlb_gen + * will be zero. + */ + struct mm_struct *mm; + unsigned long start; + unsigned long end; + u64 new_tlb_gen; }; #define local_flush_tlb() __flush_tlb() @@ -256,12 +367,10 @@ static inline void flush_tlb_page(struct vm_area_struct *vma, unsigned long a) void native_flush_tlb_others(const struct cpumask *cpumask, const struct flush_tlb_info *info); -#define TLBSTATE_OK 1 -#define TLBSTATE_LAZY 2 - static inline void arch_tlbbatch_add_mm(struct arch_tlbflush_unmap_batch *batch, struct mm_struct *mm) { + inc_mm_tlb_gen(mm); cpumask_or(&batch->cpumask, &batch->cpumask, mm_cpumask(mm)); } |