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From: Andy Lutomirski <luto@kernel.org>
To: x86@kernel.org, linux-kernel@vger.kernel.org
Cc: Borislav Petkov <bp@alien8.de>, Brian Gerst <brgerst@gmail.com>,
	Dave Hansen <dave.hansen@linux.intel.com>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Oleg Nesterov <oleg@redhat.com>,
	"linux-mm@kvack.org" <linux-mm@kvack.org>,
	Andy Lutomirski <luto@kernel.org>
Subject: [RFC 04/13] x86/mm: If INVPCID is available, use it to flush global mappings
Date: Fri,  8 Jan 2016 15:15:22 -0800	[thread overview]
Message-ID: <1ddac818ae831c89dc4f680bbf4bfac7b6ba2b4c.1452294700.git.luto@kernel.org> (raw)
In-Reply-To: <cover.1452294700.git.luto@kernel.org>
In-Reply-To: <cover.1452294700.git.luto@kernel.org>

On my Skylake laptop, INVPCID function 2 (flush absolutely
everything) takes about 376ns, whereas saving flags, twiddling
CR4.PGE to flush global mappings, and restoring flags takes about
539ns.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
---
 arch/x86/include/asm/tlbflush.h | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/arch/x86/include/asm/tlbflush.h b/arch/x86/include/asm/tlbflush.h
index 20fc38d8478a..4eba5164430d 100644
--- a/arch/x86/include/asm/tlbflush.h
+++ b/arch/x86/include/asm/tlbflush.h
@@ -145,6 +145,15 @@ static inline void __native_flush_tlb_global(void)
 {
 	unsigned long flags;
 
+	if (static_cpu_has_safe(X86_FEATURE_INVPCID)) {
+		/*
+		 * Using INVPCID is considerably faster than a pair of writes
+		 * to CR4 sandwiched inside an IRQ flag save/restore.
+		 */
+		invpcid_flush_everything();
+		return;
+	}
+
 	/*
 	 * Read-modify-write to CR4 - protect it from preemption and
 	 * from interrupts. (Use the raw variant because this code can
-- 
2.5.0

  parent reply	other threads:[~2016-01-08 23:15 UTC|newest]

Thread overview: 43+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-01-08 23:15 [RFC 00/13] x86/mm: PCID and INVPCID Andy Lutomirski
2016-01-08 23:15 ` [RFC 01/13] x86/paravirt: Turn KASAN off for parvirt.o Andy Lutomirski
2016-01-10 18:59   ` Borislav Petkov
2016-01-11 12:51     ` Andrey Ryabinin
2016-01-11 12:51       ` [PATCH 1/2] x86/kasan: clear kasan_zero_page after TLB flush Andrey Ryabinin
2016-01-18 22:24         ` Andy Lutomirski
2016-02-09 16:06         ` [tip:x86/mm] x86/kasan: Clear " tip-bot for Andrey Ryabinin
2016-01-11 12:51       ` [PATCH 2/2] x86/kasan: write protect kasan zero shadow Andrey Ryabinin
2016-01-18 22:24         ` Andy Lutomirski
2016-02-09 16:07         ` [tip:x86/mm] x86/kasan: Write " tip-bot for Andrey Ryabinin
2016-01-29 10:35       ` [RFC 01/13] x86/paravirt: Turn KASAN off for parvirt.o Borislav Petkov
2016-01-08 23:15 ` [RFC 02/13] x86/mm: Add INVPCID helpers Andy Lutomirski
2016-01-08 23:15 ` [RFC 03/13] x86/mm: Add a noinvpcid option to turn off INVPCID Andy Lutomirski
2016-01-08 23:15 ` Andy Lutomirski [this message]
2016-01-08 23:15 ` [RFC 05/13] x86/mm: Add barriers and document switch_mm-vs-flush synchronization Andy Lutomirski
2016-06-03 17:42   ` Nadav Amit
2016-06-09 17:24     ` Andy Lutomirski
2016-06-09 19:45       ` Nadav Amit
2016-09-06  1:22   ` Wanpeng Li
2016-01-08 23:15 ` [RFC 06/13] x86/mm: Disable PCID on 32-bit kernels Andy Lutomirski
2016-01-08 23:15 ` [RFC 07/13] x86/mm: Add nopcid to turn off PCID Andy Lutomirski
2016-01-08 23:15 ` [RFC 08/13] x86/mm: Teach CR3 readers about PCID Andy Lutomirski
2016-01-08 23:15 ` [RFC 09/13] x86/mm: Disable interrupts when flushing the TLB using CR3 Andy Lutomirski
2016-01-08 23:41   ` Linus Torvalds
2016-01-09  0:18     ` Andy Lutomirski
2016-01-09  2:20       ` Linus Torvalds
2016-01-11 10:51         ` Ingo Molnar
2016-01-13 23:32           ` Andy Lutomirski
2016-01-13 23:35         ` Andy Lutomirski
2016-01-13 23:43           ` Dave Hansen
2016-01-13 23:51             ` Andy Lutomirski
2016-01-13 23:56               ` Dave Hansen
2016-01-14  0:34                 ` Andy Lutomirski
2016-01-08 23:15 ` [RFC 10/13] x86/mm: Factor out remote TLB flushing Andy Lutomirski
2016-01-08 23:15 ` [RFC 11/13] x86/mm: Build arch/x86/mm/tlb.c even on !SMP Andy Lutomirski
2016-01-08 23:55   ` Dave Hansen
2016-01-08 23:15 ` [RFC 12/13] x86/mm: Uninline switch_mm Andy Lutomirski
2016-01-08 23:15 ` [RFC 13/13] x86/mm: Try to preserve old TLB entries using PCID Andy Lutomirski
2016-01-09  0:27   ` Dave Hansen
2016-01-09  2:19     ` Andy Lutomirski
2016-01-08 23:31 ` [RFC 00/13] x86/mm: PCID and INVPCID Linus Torvalds
2016-01-08 23:36   ` Andy Lutomirski
2016-01-08 23:42     ` Linus Torvalds

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