linux-kernel - [tip:x86/mm] x86/mm/cpa: Unconditionally avoid WBINDV when we can

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Date:   Thu, 27 Sep 2018 11:53:05 -0700
From:   tip-bot for Peter Zijlstra <tipbot@...or.com>
To:     linux-tip-commits@...r.kernel.org
Cc:     dave.hansen@...el.com, peterz@...radead.org, bin.yang@...el.com,
        mark.gross@...el.com, mingo@...nel.org,
        linux-kernel@...r.kernel.org, hpa@...or.com, tglx@...utronix.de
Subject: [tip:x86/mm] x86/mm/cpa: Unconditionally avoid WBINDV when we can

Commit-ID:  ddd07b750382adc2b78fdfbec47af8a6e0d8ef37
Gitweb:     https://git.kernel.org/tip/ddd07b750382adc2b78fdfbec47af8a6e0d8ef37
Author:     Peter Zijlstra <peterz@...radead.org>
AuthorDate: Wed, 19 Sep 2018 10:50:19 +0200
Committer:  Thomas Gleixner <tglx@...utronix.de>
CommitDate: Thu, 27 Sep 2018 20:39:41 +0200

x86/mm/cpa: Unconditionally avoid WBINDV when we can

CAT has happened, WBINDV is bad (even before CAT blowing away the
entire cache on a multi-core platform wasn't nice), try not to use it
ever.

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/20180919085947.933674526@infradead.org

---
 arch/x86/mm/pageattr.c | 18 ++----------------
 1 file changed, 2 insertions(+), 16 deletions(-)

diff --git a/arch/x86/mm/pageattr.c b/arch/x86/mm/pageattr.c
index b6a4c638f086..bd9b0ac07352 100644
--- a/arch/x86/mm/pageattr.c
+++ b/arch/x86/mm/pageattr.c
@@ -319,26 +319,12 @@ static void cpa_flush_array(unsigned long *start, int numpages, int cache,
 			    int in_flags, struct page **pages)
 {
 	unsigned int i, level;
-#ifdef CONFIG_PREEMPT
-	/*
-	 * Avoid wbinvd() because it causes latencies on all CPUs,
-	 * regardless of any CPU isolation that may be in effect.
-	 *
-	 * This should be extended for CAT enabled systems independent of
-	 * PREEMPT because wbinvd() does not respect the CAT partitions and
-	 * this is exposed to unpriviledged users through the graphics
-	 * subsystem.
-	 */
-	unsigned long do_wbinvd = 0;
-#else
-	unsigned long do_wbinvd = cache && numpages >= 1024; /* 4M threshold */
-#endif
 
 	BUG_ON(irqs_disabled() && !early_boot_irqs_disabled);
 
-	on_each_cpu(__cpa_flush_all, (void *) do_wbinvd, 1);
+	flush_tlb_all();
 
-	if (!cache || do_wbinvd)
+	if (!cache)
 		return;
 
 	/*