linux-kernel - [tip:x86/mm] x86/mm/cpa: Optimize __cpa_flush

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Date:   Thu, 27 Sep 2018 11:55:52 -0700
From:   tip-bot for Peter Zijlstra <tipbot@...or.com>
To:     linux-tip-commits@...r.kernel.org
Cc:     dave.hansen@...el.com, tglx@...utronix.de, peterz@...radead.org,
        bin.yang@...el.com, mark.gross@...el.com, mingo@...nel.org,
        linux-kernel@...r.kernel.org, hpa@...or.com
Subject: [tip:x86/mm] x86/mm/cpa: Optimize __cpa_flush_range()

Commit-ID:  7904ba8a66f400182a204893c92098994e22a88d
Gitweb:     https://git.kernel.org/tip/7904ba8a66f400182a204893c92098994e22a88d
Author:     Peter Zijlstra <peterz@...radead.org>
AuthorDate: Wed, 19 Sep 2018 10:50:24 +0200
Committer:  Thomas Gleixner <tglx@...utronix.de>
CommitDate: Thu, 27 Sep 2018 20:39:42 +0200

x86/mm/cpa: Optimize __cpa_flush_range()

If we IPI for WBINDV, then we might as well kill the entire TLB too.
But if we don't have to invalidate cache, there is no reason not to
use a range TLB flush.

Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
Reviewed-by: Dave Hansen <dave.hansen@...el.com>
Cc: Bin Yang <bin.yang@...el.com>
Cc: Mark Gross <mark.gross@...el.com>
Link: https://lkml.kernel.org/r/20180919085948.195633798@infradead.org

---
 arch/x86/mm/pageattr.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/mm/pageattr.c b/arch/x86/mm/pageattr.c
index dc552824e86a..62bb30b4bd2a 100644
--- a/arch/x86/mm/pageattr.c
+++ b/arch/x86/mm/pageattr.c
@@ -291,7 +291,7 @@ static bool __cpa_flush_range(unsigned long start, int numpages, int cache)
 
 	WARN_ON(PAGE_ALIGN(start) != start);
 
-	if (!static_cpu_has(X86_FEATURE_CLFLUSH)) {
+	if (cache && !static_cpu_has(X86_FEATURE_CLFLUSH)) {
 		cpa_flush_all(cache);
 		return true;
 	}