1 /* SPDX-License-Identifier: GPL-2.0 */
2 #ifndef _ASM_X86_TLBFLUSH_H
3 #define _ASM_X86_TLBFLUSH_H
6 #include <linux/sched.h>
8 #include <asm/processor.h>
9 #include <asm/cpufeature.h>
10 #include <asm/special_insns.h>
12 #include <asm/invpcid.h>
14 static inline u64
inc_mm_tlb_gen(struct mm_struct
*mm
)
17 * Bump the generation count. This also serves as a full barrier
18 * that synchronizes with switch_mm(): callers are required to order
19 * their read of mm_cpumask after their writes to the paging
22 return atomic64_inc_return(&mm
->context
.tlb_gen
);
25 /* There are 12 bits of space for ASIDS in CR3 */
26 #define CR3_HW_ASID_BITS 12
28 * When enabled, PAGE_TABLE_ISOLATION consumes a single bit for
29 * user/kernel switches
31 #define PTI_CONSUMED_ASID_BITS 0
33 #define CR3_AVAIL_ASID_BITS (CR3_HW_ASID_BITS - PTI_CONSUMED_ASID_BITS)
35 * ASIDs are zero-based: 0->MAX_AVAIL_ASID are valid. -1 below to account
36 * for them being zero-based. Another -1 is because ASID 0 is reserved for
37 * use by non-PCID-aware users.
39 #define MAX_ASID_AVAILABLE ((1 << CR3_AVAIL_ASID_BITS) - 2)
41 static inline u16
kern_pcid(u16 asid
)
43 VM_WARN_ON_ONCE(asid
> MAX_ASID_AVAILABLE
);
45 * If PCID is on, ASID-aware code paths put the ASID+1 into the
46 * PCID bits. This serves two purposes. It prevents a nasty
47 * situation in which PCID-unaware code saves CR3, loads some other
48 * value (with PCID == 0), and then restores CR3, thus corrupting
49 * the TLB for ASID 0 if the saved ASID was nonzero. It also means
50 * that any bugs involving loading a PCID-enabled CR3 with
51 * CR4.PCIDE off will trigger deterministically.
57 static inline unsigned long build_cr3(pgd_t
*pgd
, u16 asid
)
59 if (static_cpu_has(X86_FEATURE_PCID
)) {
60 return __sme_pa(pgd
) | kern_pcid(asid
);
62 VM_WARN_ON_ONCE(asid
!= 0);
67 static inline unsigned long build_cr3_noflush(pgd_t
*pgd
, u16 asid
)
69 VM_WARN_ON_ONCE(asid
> MAX_ASID_AVAILABLE
);
70 VM_WARN_ON_ONCE(!this_cpu_has(X86_FEATURE_PCID
));
71 return __sme_pa(pgd
) | kern_pcid(asid
) | CR3_NOFLUSH
;
74 #ifdef CONFIG_PARAVIRT
75 #include <asm/paravirt.h>
77 #define __flush_tlb() __native_flush_tlb()
78 #define __flush_tlb_global() __native_flush_tlb_global()
79 #define __flush_tlb_single(addr) __native_flush_tlb_single(addr)
82 static inline bool tlb_defer_switch_to_init_mm(void)
85 * If we have PCID, then switching to init_mm is reasonably
86 * fast. If we don't have PCID, then switching to init_mm is
87 * quite slow, so we try to defer it in the hopes that we can
88 * avoid it entirely. The latter approach runs the risk of
89 * receiving otherwise unnecessary IPIs.
91 * This choice is just a heuristic. The tlb code can handle this
92 * function returning true or false regardless of whether we have
95 return !static_cpu_has(X86_FEATURE_PCID
);
99 * 6 because 6 should be plenty and struct tlb_state will fit in
102 #define TLB_NR_DYN_ASIDS 6
111 * cpu_tlbstate.loaded_mm should match CR3 whenever interrupts
112 * are on. This means that it may not match current->active_mm,
113 * which will contain the previous user mm when we're in lazy TLB
114 * mode even if we've already switched back to swapper_pg_dir.
116 struct mm_struct
*loaded_mm
;
121 * We can be in one of several states:
123 * - Actively using an mm. Our CPU's bit will be set in
124 * mm_cpumask(loaded_mm) and is_lazy == false;
126 * - Not using a real mm. loaded_mm == &init_mm. Our CPU's bit
127 * will not be set in mm_cpumask(&init_mm) and is_lazy == false.
129 * - Lazily using a real mm. loaded_mm != &init_mm, our bit
130 * is set in mm_cpumask(loaded_mm), but is_lazy == true.
131 * We're heuristically guessing that the CR3 load we
132 * skipped more than makes up for the overhead added by
138 * Access to this CR4 shadow and to H/W CR4 is protected by
139 * disabling interrupts when modifying either one.
144 * This is a list of all contexts that might exist in the TLB.
145 * There is one per ASID that we use, and the ASID (what the
146 * CPU calls PCID) is the index into ctxts.
148 * For each context, ctx_id indicates which mm the TLB's user
149 * entries came from. As an invariant, the TLB will never
150 * contain entries that are out-of-date as when that mm reached
151 * the tlb_gen in the list.
153 * To be clear, this means that it's legal for the TLB code to
154 * flush the TLB without updating tlb_gen. This can happen
155 * (for now, at least) due to paravirt remote flushes.
157 * NB: context 0 is a bit special, since it's also used by
158 * various bits of init code. This is fine -- code that
159 * isn't aware of PCID will end up harmlessly flushing
162 struct tlb_context ctxs
[TLB_NR_DYN_ASIDS
];
164 DECLARE_PER_CPU_SHARED_ALIGNED(struct tlb_state
, cpu_tlbstate
);
166 /* Initialize cr4 shadow for this CPU. */
167 static inline void cr4_init_shadow(void)
169 this_cpu_write(cpu_tlbstate
.cr4
, __read_cr4());
172 /* Set in this cpu's CR4. */
173 static inline void cr4_set_bits(unsigned long mask
)
177 cr4
= this_cpu_read(cpu_tlbstate
.cr4
);
178 if ((cr4
| mask
) != cr4
) {
180 this_cpu_write(cpu_tlbstate
.cr4
, cr4
);
185 /* Clear in this cpu's CR4. */
186 static inline void cr4_clear_bits(unsigned long mask
)
190 cr4
= this_cpu_read(cpu_tlbstate
.cr4
);
191 if ((cr4
& ~mask
) != cr4
) {
193 this_cpu_write(cpu_tlbstate
.cr4
, cr4
);
198 static inline void cr4_toggle_bits(unsigned long mask
)
202 cr4
= this_cpu_read(cpu_tlbstate
.cr4
);
204 this_cpu_write(cpu_tlbstate
.cr4
, cr4
);
208 /* Read the CR4 shadow. */
209 static inline unsigned long cr4_read_shadow(void)
211 return this_cpu_read(cpu_tlbstate
.cr4
);
215 * Save some of cr4 feature set we're using (e.g. Pentium 4MB
216 * enable and PPro Global page enable), so that any CPU's that boot
217 * up after us can get the correct flags. This should only be used
218 * during boot on the boot cpu.
220 extern unsigned long mmu_cr4_features
;
221 extern u32
*trampoline_cr4_features
;
223 static inline void cr4_set_bits_and_update_boot(unsigned long mask
)
225 mmu_cr4_features
|= mask
;
226 if (trampoline_cr4_features
)
227 *trampoline_cr4_features
= mmu_cr4_features
;
231 extern void initialize_tlbstate_and_flush(void);
234 * flush the entire current user mapping
236 static inline void __native_flush_tlb(void)
239 * If current->mm == NULL then we borrow a mm which may change during a
240 * task switch and therefore we must not be preempted while we write CR3
244 native_write_cr3(__native_read_cr3());
251 static inline void __native_flush_tlb_global(void)
253 unsigned long cr4
, flags
;
255 if (static_cpu_has(X86_FEATURE_INVPCID
)) {
257 * Using INVPCID is considerably faster than a pair of writes
258 * to CR4 sandwiched inside an IRQ flag save/restore.
265 * Read-modify-write to CR4 - protect it from preemption and
266 * from interrupts. (Use the raw variant because this code can
267 * be called from deep inside debugging code.)
269 raw_local_irq_save(flags
);
271 cr4
= this_cpu_read(cpu_tlbstate
.cr4
);
273 native_write_cr4(cr4
^ X86_CR4_PGE
);
274 /* write old PGE again and flush TLBs */
275 native_write_cr4(cr4
);
277 raw_local_irq_restore(flags
);
281 * flush one page in the user mapping
283 static inline void __native_flush_tlb_single(unsigned long addr
)
285 asm volatile("invlpg (%0)" ::"r" (addr
) : "memory");
291 static inline void __flush_tlb_all(void)
293 if (boot_cpu_has(X86_FEATURE_PGE
)) {
294 __flush_tlb_global();
297 * !PGE -> !PCID (setup_pcid()), thus every flush is total.
303 * Note: if we somehow had PCID but not PGE, then this wouldn't work --
304 * we'd end up flushing kernel translations for the current ASID but
305 * we might fail to flush kernel translations for other cached ASIDs.
307 * To avoid this issue, we force PCID off if PGE is off.
312 * flush one page in the kernel mapping
314 static inline void __flush_tlb_one(unsigned long addr
)
316 count_vm_tlb_event(NR_TLB_LOCAL_FLUSH_ONE
);
317 __flush_tlb_single(addr
);
320 #define TLB_FLUSH_ALL -1UL
325 * - flush_tlb_all() flushes all processes TLBs
326 * - flush_tlb_mm(mm) flushes the specified mm context TLB's
327 * - flush_tlb_page(vma, vmaddr) flushes one page
328 * - flush_tlb_range(vma, start, end) flushes a range of pages
329 * - flush_tlb_kernel_range(start, end) flushes a range of kernel pages
330 * - flush_tlb_others(cpumask, info) flushes TLBs on other cpus
332 * ..but the i386 has somewhat limited tlb flushing capabilities,
333 * and page-granular flushes are available only on i486 and up.
335 struct flush_tlb_info
{
337 * We support several kinds of flushes.
339 * - Fully flush a single mm. .mm will be set, .end will be
340 * TLB_FLUSH_ALL, and .new_tlb_gen will be the tlb_gen to
341 * which the IPI sender is trying to catch us up.
343 * - Partially flush a single mm. .mm will be set, .start and
344 * .end will indicate the range, and .new_tlb_gen will be set
345 * such that the changes between generation .new_tlb_gen-1 and
346 * .new_tlb_gen are entirely contained in the indicated range.
348 * - Fully flush all mms whose tlb_gens have been updated. .mm
349 * will be NULL, .end will be TLB_FLUSH_ALL, and .new_tlb_gen
352 struct mm_struct
*mm
;
358 #define local_flush_tlb() __flush_tlb()
360 #define flush_tlb_mm(mm) flush_tlb_mm_range(mm, 0UL, TLB_FLUSH_ALL, 0UL)
362 #define flush_tlb_range(vma, start, end) \
363 flush_tlb_mm_range(vma->vm_mm, start, end, vma->vm_flags)
365 extern void flush_tlb_all(void);
366 extern void flush_tlb_mm_range(struct mm_struct
*mm
, unsigned long start
,
367 unsigned long end
, unsigned long vmflag
);
368 extern void flush_tlb_kernel_range(unsigned long start
, unsigned long end
);
370 static inline void flush_tlb_page(struct vm_area_struct
*vma
, unsigned long a
)
372 flush_tlb_mm_range(vma
->vm_mm
, a
, a
+ PAGE_SIZE
, VM_NONE
);
375 void native_flush_tlb_others(const struct cpumask
*cpumask
,
376 const struct flush_tlb_info
*info
);
378 static inline void arch_tlbbatch_add_mm(struct arch_tlbflush_unmap_batch
*batch
,
379 struct mm_struct
*mm
)
382 cpumask_or(&batch
->cpumask
, &batch
->cpumask
, mm_cpumask(mm
));
385 extern void arch_tlbbatch_flush(struct arch_tlbflush_unmap_batch
*batch
);
387 #ifndef CONFIG_PARAVIRT
388 #define flush_tlb_others(mask, info) \
389 native_flush_tlb_others(mask, info)
392 #endif /* _ASM_X86_TLBFLUSH_H */