linux-kernel - [PATCH 6/8] x86/mm/cpa: Move CLFLUSH test into cpa_flush

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Date:   Wed, 19 Sep 2018 10:50:22 +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 6/8] x86/mm/cpa: Move CLFLUSH test into cpa_flush_array()

Rather than guarding cpa_flush_array() users with a CLFLUSH test, put
it inside.

Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
---
 arch/x86/mm/pageattr.c |   29 +++++++++++++++++------------
 1 file changed, 17 insertions(+), 12 deletions(-)

--- a/arch/x86/mm/pageattr.c
+++ b/arch/x86/mm/pageattr.c
@@ -328,6 +328,11 @@ static void cpa_flush_array(unsigned lon
 
 	BUG_ON(irqs_disabled() && !early_boot_irqs_disabled);
 
+	if (!static_cpu_has(X86_FEATURE_CLFLUSH)) {
+		cpa_flush_all(cache);
+		return;
+	}
+
 	flush_tlb_kernel_range(baddr, baddr + PAGE_SIZE * numpages);
 
 	if (!cache)
@@ -1753,19 +1758,19 @@ static int change_page_attr_set_clr(unsi
 	cache = !!pgprot2cachemode(mask_set);
 
 	/*
-	 * On success we use CLFLUSH, when the CPU supports it to
-	 * avoid the WBINVD. If the CPU does not support it and in the
-	 * error case we fall back to cpa_flush_all (which uses
-	 * WBINVD):
-	 */
-	if (!ret && boot_cpu_has(X86_FEATURE_CLFLUSH)) {
-		if (cpa.flags & (CPA_PAGES_ARRAY | CPA_ARRAY)) {
-			cpa_flush_array(baddr, addr, numpages, cache,
-					cpa.flags, pages);
-		} else
-			cpa_flush_range(baddr, numpages, cache);
-	} else
+	 * On error; flush everything to be sure.
+	 */
+	if (ret) {
 		cpa_flush_all(cache);
+		goto out;
+	}
+
+	if (cpa.flags & (CPA_PAGES_ARRAY | CPA_ARRAY)) {
+		cpa_flush_array(baddr, addr, numpages, cache,
+				cpa.flags, pages);
+	} else {
+		cpa_flush_range(baddr, numpages, cache);
+	}
 
 out:
 	return ret;