X-Git-Url: https://git.proxmox.com/?a=blobdiff_plain;f=arch%2Fx86%2Finclude%2Fasm%2Ftlbflush.h;h=4a08dd2ab32ade77dcbfff6a8e8b77f5d5e43764;hb=52c90f2d32bfa7d6eccd66a56c44ace1f78fbadd;hp=3e2227386abe592c65ba25b7c8453fafce8736f7;hpb=b5fc6d943808b570bdfbec80f40c6b3855f1c48b;p=mirror_ubuntu-bionic-kernel.git diff --git a/arch/x86/include/asm/tlbflush.h b/arch/x86/include/asm/tlbflush.h index 3e2227386abe..4a08dd2ab32a 100644 --- a/arch/x86/include/asm/tlbflush.h +++ b/arch/x86/include/asm/tlbflush.h @@ -9,64 +9,130 @@ #include #include #include +#include +#include +#include -static inline void __invpcid(unsigned long pcid, unsigned long addr, - unsigned long type) -{ - struct { u64 d[2]; } desc = { { pcid, addr } }; +/* + * The x86 feature is called PCID (Process Context IDentifier). It is similar + * to what is traditionally called ASID on the RISC processors. + * + * We don't use the traditional ASID implementation, where each process/mm gets + * its own ASID and flush/restart when we run out of ASID space. + * + * Instead we have a small per-cpu array of ASIDs and cache the last few mm's + * that came by on this CPU, allowing cheaper switch_mm between processes on + * this CPU. + * + * We end up with different spaces for different things. To avoid confusion we + * use different names for each of them: + * + * ASID - [0, TLB_NR_DYN_ASIDS-1] + * the canonical identifier for an mm + * + * kPCID - [1, TLB_NR_DYN_ASIDS] + * the value we write into the PCID part of CR3; corresponds to the + * ASID+1, because PCID 0 is special. + * + * uPCID - [2048 + 1, 2048 + TLB_NR_DYN_ASIDS] + * for KPTI each mm has two address spaces and thus needs two + * PCID values, but we can still do with a single ASID denomination + * for each mm. Corresponds to kPCID + 2048. + * + */ - /* - * The memory clobber is because the whole point is to invalidate - * stale TLB entries and, especially if we're flushing global - * mappings, we don't want the compiler to reorder any subsequent - * memory accesses before the TLB flush. - * - * The hex opcode is invpcid (%ecx), %eax in 32-bit mode and - * invpcid (%rcx), %rax in long mode. - */ - asm volatile (".byte 0x66, 0x0f, 0x38, 0x82, 0x01" - : : "m" (desc), "a" (type), "c" (&desc) : "memory"); -} +/* There are 12 bits of space for ASIDS in CR3 */ +#define CR3_HW_ASID_BITS 12 + +/* + * When enabled, PAGE_TABLE_ISOLATION consumes a single bit for + * user/kernel switches + */ +#ifdef CONFIG_PAGE_TABLE_ISOLATION +# define PTI_CONSUMED_PCID_BITS 1 +#else +# define PTI_CONSUMED_PCID_BITS 0 +#endif -#define INVPCID_TYPE_INDIV_ADDR 0 -#define INVPCID_TYPE_SINGLE_CTXT 1 -#define INVPCID_TYPE_ALL_INCL_GLOBAL 2 -#define INVPCID_TYPE_ALL_NON_GLOBAL 3 +#define CR3_AVAIL_PCID_BITS (X86_CR3_PCID_BITS - PTI_CONSUMED_PCID_BITS) -/* Flush all mappings for a given pcid and addr, not including globals. */ -static inline void invpcid_flush_one(unsigned long pcid, - unsigned long addr) -{ - __invpcid(pcid, addr, INVPCID_TYPE_INDIV_ADDR); -} +/* + * ASIDs are zero-based: 0->MAX_AVAIL_ASID are valid. -1 below to account + * for them being zero-based. Another -1 is because PCID 0 is reserved for + * use by non-PCID-aware users. + */ +#define MAX_ASID_AVAILABLE ((1 << CR3_AVAIL_PCID_BITS) - 2) + +/* + * 6 because 6 should be plenty and struct tlb_state will fit in two cache + * lines. + */ +#define TLB_NR_DYN_ASIDS 6 -/* Flush all mappings for a given PCID, not including globals. */ -static inline void invpcid_flush_single_context(unsigned long pcid) +/* + * Given @asid, compute kPCID + */ +static inline u16 kern_pcid(u16 asid) { - __invpcid(pcid, 0, INVPCID_TYPE_SINGLE_CTXT); + VM_WARN_ON_ONCE(asid > MAX_ASID_AVAILABLE); + +#ifdef CONFIG_PAGE_TABLE_ISOLATION + /* + * Make sure that the dynamic ASID space does not confict with the + * bit we are using to switch between user and kernel ASIDs. + */ + BUILD_BUG_ON(TLB_NR_DYN_ASIDS >= (1 << X86_CR3_PTI_SWITCH_BIT)); + + /* + * The ASID being passed in here should have respected the + * MAX_ASID_AVAILABLE and thus never have the switch bit set. + */ + VM_WARN_ON_ONCE(asid & (1 << X86_CR3_PTI_SWITCH_BIT)); +#endif + /* + * The dynamically-assigned ASIDs that get passed in are small + * (context.tlb_gen); + VM_WARN_ON_ONCE(asid > MAX_ASID_AVAILABLE); + VM_WARN_ON_ONCE(!this_cpu_has(X86_FEATURE_PCID)); + return __sme_pa(pgd) | kern_pcid(asid) | CR3_NOFLUSH; } #ifdef CONFIG_PARAVIRT @@ -93,12 +159,6 @@ static inline bool tlb_defer_switch_to_init_mm(void) 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; @@ -132,6 +192,24 @@ struct tlb_state { */ bool is_lazy; + /* + * If set we changed the page tables in such a way that we + * needed an invalidation of all contexts (aka. PCIDs / ASIDs). + * This tells us to go invalidate all the non-loaded ctxs[] + * on the next context switch. + * + * The current ctx was kept up-to-date as it ran and does not + * need to be invalidated. + */ + bool invalidate_other; + + /* + * Mask that contains TLB_NR_DYN_ASIDS+1 bits to indicate + * the corresponding user PCID needs a flush next time we + * switch to it; see SWITCH_TO_USER_CR3. + */ + unsigned short user_pcid_flush_mask; + /* * Access to this CR4 shadow and to H/W CR4 is protected by * disabling interrupts when modifying either one. @@ -167,40 +245,43 @@ static inline void cr4_init_shadow(void) this_cpu_write(cpu_tlbstate.cr4, __read_cr4()); } +static inline void __cr4_set(unsigned long cr4) +{ + lockdep_assert_irqs_disabled(); + this_cpu_write(cpu_tlbstate.cr4, cr4); + __write_cr4(cr4); +} + /* Set in this cpu's CR4. */ static inline void cr4_set_bits(unsigned long mask) { - unsigned long cr4; + unsigned long cr4, flags; + local_irq_save(flags); cr4 = this_cpu_read(cpu_tlbstate.cr4); - if ((cr4 | mask) != cr4) { - cr4 |= mask; - this_cpu_write(cpu_tlbstate.cr4, cr4); - __write_cr4(cr4); - } + if ((cr4 | mask) != cr4) + __cr4_set(cr4 | mask); + local_irq_restore(flags); } /* Clear in this cpu's CR4. */ static inline void cr4_clear_bits(unsigned long mask) { - unsigned long cr4; + unsigned long cr4, flags; + local_irq_save(flags); cr4 = this_cpu_read(cpu_tlbstate.cr4); - if ((cr4 & ~mask) != cr4) { - cr4 &= ~mask; - this_cpu_write(cpu_tlbstate.cr4, cr4); - __write_cr4(cr4); - } + if ((cr4 & ~mask) != cr4) + __cr4_set(cr4 & ~mask); + local_irq_restore(flags); } -static inline void cr4_toggle_bits(unsigned long mask) +static inline void cr4_toggle_bits_irqsoff(unsigned long mask) { unsigned long cr4; cr4 = this_cpu_read(cpu_tlbstate.cr4); - cr4 ^= mask; - this_cpu_write(cpu_tlbstate.cr4, cr4); - __write_cr4(cr4); + __cr4_set(cr4 ^ mask); } /* Read the CR4 shadow. */ @@ -209,6 +290,14 @@ static inline unsigned long cr4_read_shadow(void) return this_cpu_read(cpu_tlbstate.cr4); } +/* + * Mark all other ASIDs as invalid, preserves the current. + */ +static inline void invalidate_other_asid(void) +{ + this_cpu_write(cpu_tlbstate.invalidate_other, true); +} + /* * Save some of cr4 feature set we're using (e.g. Pentium 4MB * enable and PPro Global page enable), so that any CPU's that boot @@ -228,18 +317,53 @@ static inline void cr4_set_bits_and_update_boot(unsigned long mask) extern void initialize_tlbstate_and_flush(void); +/* + * Given an ASID, flush the corresponding user ASID. We can delay this + * until the next time we switch to it. + * + * See SWITCH_TO_USER_CR3. + */ +static inline void invalidate_user_asid(u16 asid) +{ + /* There is no user ASID if address space separation is off */ + if (!IS_ENABLED(CONFIG_PAGE_TABLE_ISOLATION)) + return; + + /* + * We only have a single ASID if PCID is off and the CR3 + * write will have flushed it. + */ + if (!cpu_feature_enabled(X86_FEATURE_PCID)) + return; + + if (!static_cpu_has(X86_FEATURE_PTI)) + return; + + __set_bit(kern_pcid(asid), + (unsigned long *)this_cpu_ptr(&cpu_tlbstate.user_pcid_flush_mask)); +} + +/* + * flush the entire current user mapping + */ static inline void __native_flush_tlb(void) { /* - * If current->mm == NULL then we borrow a mm which may change during a - * task switch and therefore we must not be preempted while we write CR3 - * back: + * Preemption or interrupts must be disabled to protect the access + * to the per CPU variable and to prevent being preempted between + * read_cr3() and write_cr3(). */ - preempt_disable(); + WARN_ON_ONCE(preemptible()); + + invalidate_user_asid(this_cpu_read(cpu_tlbstate.loaded_mm_asid)); + + /* If current->mm == NULL then the read_cr3() "borrows" an mm */ native_write_cr3(__native_read_cr3()); - preempt_enable(); } +/* + * flush everything + */ static inline void __native_flush_tlb_global(void) { unsigned long cr4, flags; @@ -248,6 +372,8 @@ static inline void __native_flush_tlb_global(void) /* * Using INVPCID is considerably faster than a pair of writes * to CR4 sandwiched inside an IRQ flag save/restore. + * + * Note, this works with CR4.PCIDE=0 or 1. */ invpcid_flush_all(); return; @@ -269,31 +395,60 @@ static inline void __native_flush_tlb_global(void) raw_local_irq_restore(flags); } +/* + * flush one page in the user mapping + */ static inline void __native_flush_tlb_single(unsigned long addr) { + u32 loaded_mm_asid = this_cpu_read(cpu_tlbstate.loaded_mm_asid); + asm volatile("invlpg (%0)" ::"r" (addr) : "memory"); + + if (!static_cpu_has(X86_FEATURE_PTI)) + return; + + /* + * Some platforms #GP if we call invpcid(type=1/2) before CR4.PCIDE=1. + * Just use invalidate_user_asid() in case we are called early. + */ + if (!this_cpu_has(X86_FEATURE_INVPCID_SINGLE)) + invalidate_user_asid(loaded_mm_asid); + else + invpcid_flush_one(user_pcid(loaded_mm_asid), addr); } +/* + * flush everything + */ static inline void __flush_tlb_all(void) { - if (boot_cpu_has(X86_FEATURE_PGE)) + if (boot_cpu_has(X86_FEATURE_PGE)) { __flush_tlb_global(); - else + } else { + /* + * !PGE -> !PCID (setup_pcid()), thus every flush is total. + */ __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. - */ + } } +/* + * flush one page in the kernel mapping + */ static inline void __flush_tlb_one(unsigned long addr) { count_vm_tlb_event(NR_TLB_LOCAL_FLUSH_ONE); __flush_tlb_single(addr); + + if (!static_cpu_has(X86_FEATURE_PTI)) + return; + + /* + * __flush_tlb_single() will have cleared the TLB entry for this ASID, + * but since kernel space is replicated across all, we must also + * invalidate all others. + */ + invalidate_other_asid(); } #define TLB_FLUSH_ALL -1UL @@ -354,6 +509,17 @@ 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); +static inline u64 inc_mm_tlb_gen(struct mm_struct *mm) +{ + /* + * 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. + */ + return atomic64_inc_return(&mm->context.tlb_gen); +} + static inline void arch_tlbbatch_add_mm(struct arch_tlbflush_unmap_batch *batch, struct mm_struct *mm) {