[RFC][PATCH 06/10] x86/mm/cpa: Optimize cpa_flush_array() TLB invalidation

Peter Zijlstra
2018-12-03T17:14:58Z

Instead of punting and doing tlb_flush_all(), do the same as
flush_tlb_kernel_range() does and use single page invalidations.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
---
arch/x86/mm/mm_internal.h | 2 ++
arch/x86/mm/pageattr.c | 42 ++++++++++++++++++++++++------------------
arch/x86/mm/tlb.c | 4 +++-
3 files changed, 29 insertions(+), 19 deletions(-)

--- a/arch/x86/mm/mm_internal.h
+++ b/arch/x86/mm/mm_internal.h
@@ -19,4 +19,6 @@ extern int after_bootmem;

void update_cache_mode_entry(unsigned entry, enum page_cache_mode cache);

+extern unsigned long tlb_single_page_flush_ceiling;
+
#endif /* __X86_MM_INTERNAL_H */
--- a/arch/x86/mm/pageattr.c
+++ b/arch/x86/mm/pageattr.c
@@ -26,6 +26,8 @@
#include <asm/pat.h>
#include <asm/set_memory.h>

+#include "mm_internal.h"
+
/*
* The current flushing context - we pass it instead of 5 arguments:
*/
@@ -346,16 +348,26 @@ static void cpa_flush_range(unsigned lon
}
}

-static void cpa_flush_array(unsigned long baddr, unsigned long *start,
- int numpages, int cache,
- int in_flags, struct page **pages)
+void __cpa_flush_array(void *data)
{
- unsigned int i, level;
+ struct cpa_data *cpa = data;
+ unsigned int i;

- if (__inv_flush_all(cache))
+ for (i = 0; i < cpa->numpages; i++)
+ __flush_tlb_one_kernel(__cpa_addr(cpa, i));
+}
+
+static void cpa_flush_array(struct cpa_data *cpa, int cache)
+{
+ unsigned int i;
+
+ if (cpa_check_flush_all(cache))
return;

- flush_tlb_all();
+ if (cpa->numpages <= tlb_single_page_flush_ceiling)
+ on_each_cpu(__cpa_flush_array, cpa, 1);
+ else
+ flush_tlb_all();

if (!cache)
return;
@@ -366,15 +378,11 @@ static void cpa_flush_array(unsigned lon
* will cause all other CPUs to flush the same
* cachelines:
*/
- for (i = 0; i < numpages; i++) {
- unsigned long addr;
+ for (i = 0; i < cpa->numpages; i++) {
+ unsigned long addr = __cpa_addr(cpa, i);
+ unsigned int level;
pte_t *pte;

- if (in_flags & CPA_PAGES_ARRAY)
- addr = (unsigned long)page_address(pages[i]);
- else
- addr = start[i];
-
pte = lookup_address(addr, &level);

/*
@@ -1771,12 +1779,10 @@ static int change_page_attr_set_clr(unsi
goto out;
}

- if (cpa.flags & (CPA_PAGES_ARRAY | CPA_ARRAY)) {
- cpa_flush_array(baddr, addr, numpages, cache,
- cpa.flags, pages);
- } else {
+ if (cpa.flags & (CPA_PAGES_ARRAY | CPA_ARRAY))
+ cpa_flush_array(&cpa, cache);
+ else
cpa_flush_range(baddr, numpages, cache);
- }

out:
return ret;
--- a/arch/x86/mm/tlb.c
+++ b/arch/x86/mm/tlb.c
@@ -15,6 +15,8 @@
#include <asm/apic.h>
#include <asm/uv/uv.h>

+#include "mm_internal.h"
+
/*
* TLB flushing, formerly SMP-only
* c/o Linus Torvalds.
@@ -721,7 +723,7 @@ void native_flush_tlb_others(const struc
*
* This is in units of pages.
*/
-static unsigned long tlb_single_page_flush_ceiling __read_mostly = 33;
+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 int stride_shift,