/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _ASM_X86_TLBFLUSH_H
#define _ASM_X86_TLBFLUSH_H
#include <linux/mm.h>
#include <linux/sched.h>
#include <asm/processor.h>
#include <asm/cpufeature.h>
#include <asm/special_insns.h>
#include <asm/smp.h>
#include <asm/invpcid.h>
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);
}
/* 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
*/
#define PTI_CONSUMED_ASID_BITS 0
#define CR3_AVAIL_ASID_BITS (CR3_HW_ASID_BITS - PTI_CONSUMED_ASID_BITS)
/*
* ASIDs are zero-based: 0->MAX_AVAIL_ASID are valid. -1 below to account
* for them being zero-based. Another -1 is because ASID 0 is reserved for
* use by non-PCID-aware users.
*/
#define MAX_ASID_AVAILABLE ((1 << CR3_AVAIL_ASID_BITS) - 2)
static inline u16 kern_pcid(u16 asid)
{
VM_WARN_ON_ONCE(asid > MAX_ASID_AVAILABLE);
/*
* If PCID is on, ASID-aware code paths put the ASID+1 into the
* PCID bits. This serves two purposes. It prevents a nasty
* situation in which PCID-unaware code saves CR3, loads some other
* value (with PCID == 0), and then restores CR3, thus corrupting
* the TLB for ASID 0 if the saved ASID was nonzero. It also means
* that any bugs involving loading a PCID-enabled CR3 with
* CR4.PCIDE off will trigger deterministically.
*/
return asid + 1;
}
struct pgd_t;
static inline unsigned long build_cr3(pgd_t *pgd, u16 asid)
{
if (static_cpu_has(X86_FEATURE_PCID)) {
return __sme_pa(pgd) | kern_pcid(asid);
} else {
VM_WARN_ON_ONCE(asid != 0);
return __sme_pa(pgd);
}
}
static inline unsigned long build_cr3_noflush(pgd_t *pgd, u16 asid)
{
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
#include <asm/paravirt.h>
#else
#define __flush_tlb() __native_flush_tlb()
#define __flush_tlb_global() __native_flush_tlb_global()
#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
* are on. This means that it may not match current->active_mm,
* which will contain the previous user mm when we're in lazy TLB
* mode even if we've already switched back to swapper_pg_dir.
*/
struct mm_struct *loaded_mm;
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);
/* Initialize cr4 shadow for this CPU. */
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, flags;
local_irq_save(flags);
cr4 = this_cpu_read(cpu_tlbstate.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, flags;
local_irq_save(flags);
cr4 = this_cpu_read(cpu_tlbstate.cr4);
if ((cr4 & ~mask) != cr4)
__cr4_set(cr4 & ~mask);
local_irq_restore(flags);
}
static inline void cr4_toggle_bits_irqsoff(unsigned long mask)
{
unsigned long cr4;
cr4 = this_cpu_read(cpu_tlbstate.cr4);
__cr4_set(cr4 ^ mask);
}
/* Read the CR4 shadow. */
static inline unsigned long cr4_read_shadow(void)
{
return this_cpu_read(cpu_tlbstate.cr4);
}
/*
* 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
* up after us can get the correct flags. This should only be used
* during boot on the boot cpu.
*/
extern unsigned long mmu_cr4_features;
extern u32 *trampoline_cr4_features;
static inline void cr4_set_bits_and_update_boot(unsigned long mask)
{
mmu_cr4_features |= mask;
if (trampoline_cr4_features)
*trampoline_cr4_features = mmu_cr4_features;
cr4_set_bits(mask);
}
extern void initialize_tlbstate_and_flush(void);
/*
* 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:
*/
preempt_disable();
native_write_cr3(__native_read_cr3());
preempt_enable();
}
/*
* flush everything
*/
static inline void __native_flush_tlb_global(void)
{
unsigned long cr4, flags;
if (static_cpu_has(X86_FEATURE_INVPCID)) {
/*
* Using INVPCID is considerably faster than a pair of writes
* to CR4 sandwiched inside an IRQ flag save/restore.
*/
invpcid_flush_all();
return;
}
/*
* Read-modify-write to CR4 - protect it from preemption and
* from interrupts. (Use the raw variant because this code can
* be called from deep inside debugging code.)
*/
raw_local_irq_save(flags);
cr4 = this_cpu_read(cpu_tlbstate.cr4);
/* toggle PGE */
native_write_cr4(cr4 ^ X86_CR4_PGE);
/* write old PGE again and flush TLBs */
native_write_cr4(cr4);
raw_local_irq_restore(flags);
}
/*
* flush one page in the user mapping
*/
static inline void __native_flush_tlb_single(unsigned long addr)
{
asm volatile("invlpg (%0)" ::"r" (addr) : "memory");
}
/*
* flush everything
*/
static inline void __flush_tlb_all(void)
{
if (boot_cpu_has(X86_FEATURE_PGE)) {
__flush_tlb_global();
} 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);
}
#define TLB_FLUSH_ALL -1UL
/*
* TLB flushing:
*
* - flush_tlb_all() flushes all processes TLBs
* - flush_tlb_mm(mm) flushes the specified mm context TLB's
* - flush_tlb_page(vma, vmaddr) flushes one page
* - flush_tlb_range(vma, start, end) flushes a range of pages
* - flush_tlb_kernel_range(start, end) flushes a range of kernel pages
* - flush_tlb_others(cpumask, info) flushes TLBs on other cpus
*
* ..but the i386 has somewhat limited tlb flushing capabilities,
* and page-granular flushes are available only on i486 and up.
*/
struct flush_tlb_info {
/*
* 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()
#define flush_tlb_mm(mm) flush_tlb_mm_range(mm, 0UL, TLB_FLUSH_ALL, 0UL)
#define flush_tlb_range(vma, start, end) \
flush_tlb_mm_range(vma->vm_mm, start, end, vma->vm_flags)
extern void flush_tlb_all(void);
extern void flush_tlb_mm_range(struct mm_struct *mm, unsigned long start,
unsigned long end, unsigned long vmflag);
extern void flush_tlb_kernel_range(unsigned long start, unsigned long end);
static inline void flush_tlb_page(struct vm_area_struct *vma, unsigned long a)
{
flush_tlb_mm_range(vma->vm_mm, a, a + PAGE_SIZE, VM_NONE);
}
void native_flush_tlb_others(const struct cpumask *cpumask,
const struct flush_tlb_info *info);
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));
}
extern void arch_tlbbatch_flush(struct arch_tlbflush_unmap_batch *batch);
#ifndef CONFIG_PARAVIRT
#define flush_tlb_others(mask, info) \
native_flush_tlb_others(mask, info)
#endif
#endif /* _ASM_X86_TLBFLUSH_H */
