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x86/mm: Give each mm TLB flush generation a unique ID

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This adds two new variables to mmu_context_t: ctx_id and tlb_gen.
ctx_id uniquely identifies the mm_struct and will never be reused.
For a given mm_struct (and hence ctx_id), tlb_gen is a monotonic
count of the number of times that a TLB flush has been requested.
The pair (ctx_id, tlb_gen) can be used as an identifier for TLB
flush actions and will be used in subsequent patches to reliably
determine whether all needed TLB flushes have occurred on a given
CPU.

This patch is split out for ease of review.  By itself, it has no
real effect other than creating and updating the new variables.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Reviewed-by: Nadav Amit <nadav.amit@gmail.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: linux-mm@kvack.org
Link: http://lkml.kernel.org/r/413a91c24dab3ed0caa5f4e4d017d87b0857f920.1498751203.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Andy Lutomirski 2017-06-29 08:53:15 -07:00 committed by Ingo Molnar
parent 4422d80ed7
commit f39681ed0f
4 changed files with 51 additions and 4 deletions
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25
arch/x86/include/asm/mmu.h
View File

@ -3,12 +3,28 @@
#include <linux/spinlock.h>
#include <linux/mutex.h>
#include <linux/atomic.h>
/*
* The x86 doesn't have a mmu context, but
* we put the segment information here.
* x86 has arch-specific MMU state beyond what lives in mm_struct.
*/
typedef struct {
/*
* ctx_id uniquely identifies this mm_struct. A ctx_id will never
* be reused, and zero is not a valid ctx_id.
*/
u64 ctx_id;
/*
* Any code that needs to do any sort of TLB flushing for this
* mm will first make its changes to the page tables, then
* increment tlb_gen, then flush. This lets the low-level
* flushing code keep track of what needs flushing.
*
* This is not used on Xen PV.
*/
atomic64_t tlb_gen;
#ifdef CONFIG_MODIFY_LDT_SYSCALL
struct ldt_struct *ldt;
#endif
@ -37,6 +53,11 @@ typedef struct {
#endif
} mm_context_t;
#define INIT_MM_CONTEXT(mm) \
.context = { \
.ctx_id = 1, \
}
void leave_mm(int cpu);
#endif /* _ASM_X86_MMU_H */

6
arch/x86/include/asm/mmu_context.h
View File

@ -12,6 +12,9 @@
#include <asm/tlbflush.h>
#include <asm/paravirt.h>
#include <asm/mpx.h>
extern atomic64_t last_mm_ctx_id;
#ifndef CONFIG_PARAVIRT
static inline void paravirt_activate_mm(struct mm_struct *prev,
struct mm_struct *next)
@ -132,6 +135,9 @@ static inline void enter_lazy_tlb(struct mm_struct *mm, struct task_struct *tsk)
static inline int init_new_context(struct task_struct *tsk,
struct mm_struct *mm)
{
mm->context.ctx_id = atomic64_inc_return(&last_mm_ctx_id);
atomic64_set(&mm->context.tlb_gen, 0);
#ifdef CONFIG_X86_INTEL_MEMORY_PROTECTION_KEYS
if (cpu_feature_enabled(X86_FEATURE_OSPKE)) {
/* pkey 0 is the default and always allocated */

18
arch/x86/include/asm/tlbflush.h
View File

@ -57,6 +57,23 @@ 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
@ -262,6 +279,7 @@ void native_flush_tlb_others(const struct cpumask *cpumask,
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));
}

6
arch/x86/mm/tlb.c
View File

@ -28,6 +28,8 @@
* Implement flush IPI by CALL_FUNCTION_VECTOR, Alex Shi
*/
atomic64_t last_mm_ctx_id = ATOMIC64_INIT(1);
void leave_mm(int cpu)
{
struct mm_struct *loaded_mm = this_cpu_read(cpu_tlbstate.loaded_mm);
@ -250,8 +252,8 @@ void flush_tlb_mm_range(struct mm_struct *mm, unsigned long start,
cpu = get_cpu();
/* Synchronize with switch_mm. */
smp_mb();
/* This is also a barrier that synchronizes with switch_mm(). */
inc_mm_tlb_gen(mm);
/* Should we flush just the requested range? */
if ((end != TLB_FLUSH_ALL) &&