[RFC][PATCH 03/11] x86/mm: Page size aware flush_tlb_mm_range()

From: Peter Zijlstra
Date: Thu Sep 13 2018 - 05:29:35 EST


Use the new tlb_get_unmap_shift() to determine the stride of the
INVLPG loop.

Cc: Will Deacon <will.deacon@xxxxxxx>
Cc: "Aneesh Kumar K.V" <aneesh.kumar@xxxxxxxxxxxxxxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: Nick Piggin <npiggin@xxxxxxxxx>
Cc: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
---
arch/x86/include/asm/tlb.h | 21 ++++++++++++++-------
arch/x86/include/asm/tlbflush.h | 10 ++++++----
arch/x86/mm/tlb.c | 10 +++++-----
3 files changed, 25 insertions(+), 16 deletions(-)

--- a/arch/x86/include/asm/tlb.h
+++ b/arch/x86/include/asm/tlb.h
@@ -6,16 +6,23 @@
#define tlb_end_vma(tlb, vma) do { } while (0)
#define __tlb_remove_tlb_entry(tlb, ptep, address) do { } while (0)

-#define tlb_flush(tlb) \
-{ \
- if (!tlb->fullmm && !tlb->need_flush_all) \
- flush_tlb_mm_range(tlb->mm, tlb->start, tlb->end, 0UL); \
- else \
- flush_tlb_mm_range(tlb->mm, 0UL, TLB_FLUSH_ALL, 0UL); \
-}
+static inline void tlb_flush(struct mmu_gather *tlb);

#include <asm-generic/tlb.h>

+static inline void tlb_flush(struct mmu_gather *tlb)
+{
+ unsigned long start = 0UL, end = TLB_FLUSH_ALL;
+ unsigned int invl_shift = tlb_get_unmap_shift(tlb);
+
+ if (!tlb->fullmm && !tlb->need_flush_all) {
+ start = tlb->start;
+ end = tlb->end;
+ }
+
+ flush_tlb_mm_range(tlb->mm, start, end, invl_shift);
+}
+
/*
* While x86 architecture in general requires an IPI to perform TLB
* shootdown, enablement code for several hypervisors overrides
--- a/arch/x86/include/asm/tlbflush.h
+++ b/arch/x86/include/asm/tlbflush.h
@@ -507,23 +507,25 @@ struct flush_tlb_info {
unsigned long start;
unsigned long end;
u64 new_tlb_gen;
+ unsigned int invl_shift;
};

#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)
+#define flush_tlb_range(vma, start, end) \
+ flush_tlb_mm_range((vma)->vm_mm, start, end, \
+ (vma)->vm_flags & VM_HUGETLB ? PMD_SHIFT : PAGE_SHIFT)

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);
+ unsigned long end, unsigned int invl_shift);
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);
+ flush_tlb_mm_range(vma->vm_mm, a, a + PAGE_SIZE, PAGE_SHIFT);
}

void native_flush_tlb_others(const struct cpumask *cpumask,
--- a/arch/x86/mm/tlb.c
+++ b/arch/x86/mm/tlb.c
@@ -522,12 +522,12 @@ static void flush_tlb_func_common(const
f->new_tlb_gen == mm_tlb_gen) {
/* Partial flush */
unsigned long addr;
- unsigned long nr_pages = (f->end - f->start) >> PAGE_SHIFT;
+ unsigned long nr_pages = (f->end - f->start) >> f->invl_shift;

addr = f->start;
while (addr < f->end) {
__flush_tlb_one_user(addr);
- addr += PAGE_SIZE;
+ addr += 1UL << f->invl_shift;
}
if (local)
count_vm_tlb_events(NR_TLB_LOCAL_FLUSH_ONE, nr_pages);
@@ -616,12 +616,13 @@ void native_flush_tlb_others(const struc
static unsigned long tlb_single_page_flush_ceiling __read_mostly = 33;

void flush_tlb_mm_range(struct mm_struct *mm, unsigned long start,
- unsigned long end, unsigned long vmflag)
+ unsigned long end, unsigned int invl_shift)
{
int cpu;

struct flush_tlb_info info __aligned(SMP_CACHE_BYTES) = {
.mm = mm,
+ .invl_shift = invl_shift,
};

cpu = get_cpu();
@@ -631,8 +632,7 @@ void flush_tlb_mm_range(struct mm_struct

/* Should we flush just the requested range? */
if ((end != TLB_FLUSH_ALL) &&
- !(vmflag & VM_HUGETLB) &&
- ((end - start) >> PAGE_SHIFT) <= tlb_single_page_flush_ceiling) {
+ ((end - start) >> invl_shift) <= tlb_single_page_flush_ceiling) {
info.start = start;
info.end = end;
} else {