linux-kernel - [RFC][PATCH 06/10] x86/mm/cpa: Optimize cpa_flush

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Message-Id: <20181203171043.430001980@infradead.org>
Date:   Mon, 03 Dec 2018 18:03:49 +0100
From:   Peter Zijlstra <peterz@...radead.org>
To:     dave.hansen@...el.com, luto@...nel.org, peterz@...radead.org
Cc:     x86@...nel.org, Tom.StDenis@....com, linux-kernel@...r.kernel.org
Subject: [RFC][PATCH 06/10] x86/mm/cpa: Optimize cpa_flush_array() TLB invalidation

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@...radead.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,