linux-kernel - [PATCH 3/8] x86/mm/cpa: Unconditionally avoid WBINDV when we can

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Message-ID: <20180919085947.933674526@infradead.org>
Date:   Wed, 19 Sep 2018 10:50:19 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     Thomas Gleixner <tglx@...utronix.de>
Cc:     linux-kernel@...r.kernel.org, x86@...nel.org,
        Peter Zijlstra <peterz@...radead.org>,
        Bin Yang <bin.yang@...el.com>,
        Dave Hansen <dave.hansen@...el.com>,
        Mark Gross <mark.gross@...el.com>
Subject: [PATCH 3/8] 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>
---
 arch/x86/mm/pageattr.c |   18 ++----------------
 1 file changed, 2 insertions(+), 16 deletions(-)

--- a/arch/x86/mm/pageattr.c
+++ b/arch/x86/mm/pageattr.c
@@ -319,26 +319,12 @@ static void cpa_flush_array(unsigned lon
 			    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;
 
 	/*