From: Thomas Gleixner <tglx@linutronix.de>
To: LKML <linux-kernel@vger.kernel.org>
Cc: x86@kernel.org, Peter Zijlstra <peterz@infradead.org>,
Bin Yang <bin.yang@intel.com>,
Dave Hansen <dave.hansen@intel.com>,
Mark Gross <mark.gross@intel.com>
Subject: [patch V2 06/10] x86/mm/cpa: Avoid static protection checks on unmap
Date: Fri, 14 Sep 2018 15:09:23 +0200 [thread overview]
Message-ID: <20180914131302.110697717@linutronix.de> (raw)
In-Reply-To: 20180914130917.155416208@linutronix.de
[-- Attachment #1: x86-mm-cpa--Avoid-static-protection-checks-on-unmap.patch --]
[-- Type: text/plain, Size: 1326 bytes --]
If the new pgprot has the PRESENT bit cleared, then conflicts vs. RW/NX are
completely irrelevant.
Before:
1G pages checked: 2
1G pages sameprot: 0
1G pages preserved: 0
2M pages checked: 540
2M pages sameprot: 466
2M pages preserved: 47
4K pages checked: 800770
4K pages set-checked: 7668
After:
1G pages checked: 2
1G pages sameprot: 0
1G pages preserved: 0
2M pages checked: 540
2M pages sameprot: 466
2M pages preserved: 47
4K pages checked: 800709
4K pages set-checked: 7668
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
arch/x86/mm/pageattr.c | 7 +++++++
1 file changed, 7 insertions(+)
--- a/arch/x86/mm/pageattr.c
+++ b/arch/x86/mm/pageattr.c
@@ -522,6 +522,13 @@ static inline pgprot_t static_protection
pgprotval_t forbidden, res;
unsigned long end;
+ /*
+ * There is no point in checking RW/NX conflicts when the requested
+ * mapping is setting the page !PRESENT.
+ */
+ if (!(pgprot_val(prot) & _PAGE_PRESENT))
+ return prot;
+
/* Operate on the virtual address */
end = start + npg * PAGE_SIZE - 1;
next prev parent reply other threads:[~2018-09-14 13:21 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-09-14 13:09 [patch V2 00/10] x86/mm/cpa: Improve large page preservation handling Thomas Gleixner
2018-09-14 13:09 ` [patch V2 01/10] x86/mm/cpa: Split, rename and clean up try_preserve_large_page() Thomas Gleixner
2018-09-14 13:09 ` [patch V2 02/10] x86/mm/cpa: Rework static_protections() Thomas Gleixner
2018-09-14 13:09 ` [patch V2 03/10] x86/mm/cpa: Allow range check for static protections Thomas Gleixner
2018-09-14 13:09 ` [patch V2 04/10] x86/mm/cpa: Add debug mechanism Thomas Gleixner
2018-09-14 23:22 ` kbuild test robot
2018-09-15 6:58 ` kbuild test robot
2018-09-15 13:06 ` [patch V3 " Thomas Gleixner
2018-09-14 13:09 ` [patch V2 05/10] x86/mm/cpa: Add large page preservation statistics Thomas Gleixner
2018-09-14 13:09 ` Thomas Gleixner [this message]
2018-09-14 13:09 ` [patch V2 07/10] x86/mm/cpa: Add sanity check for existing mappings Thomas Gleixner
2018-09-17 0:31 ` [LKP] [x86/mm/cpa] c77d419f92: WARNING:at_arch/x86/mm/pageattr.c:#__change_page_attr_set_clr kernel test robot
2018-09-17 11:05 ` Thomas Gleixner
2018-09-14 13:09 ` [patch V2 08/10] x86/mm/cpa: Optimize same protection check Thomas Gleixner
2018-09-14 13:09 ` [patch V2 09/10] x86/mm/cpa: Do the range check early Thomas Gleixner
2018-09-14 13:09 ` [patch V2 10/10] x86/mm/cpa: Avoid the 4k pages check completely Thomas Gleixner
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