From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 7E36EFC6182 for ; Fri, 14 Sep 2018 13:21:44 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 335D9204EC for ; Fri, 14 Sep 2018 13:21:44 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 335D9204EC Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linutronix.de Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728371AbeINSgK (ORCPT ); Fri, 14 Sep 2018 14:36:10 -0400 Received: from Galois.linutronix.de ([146.0.238.70]:50004 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728036AbeINSfa (ORCPT ); Fri, 14 Sep 2018 14:35:30 -0400 Received: from localhost ([127.0.0.1] helo=nanos.tec.linutronix.de) by Galois.linutronix.de with esmtp (Exim 4.80) (envelope-from ) id 1g0o1t-0006oz-6f; Fri, 14 Sep 2018 15:21:01 +0200 Message-Id: <20180914131302.026346221@linutronix.de> User-Agent: quilt/0.65 Date: Fri, 14 Sep 2018 15:09:22 +0200 From: Thomas Gleixner To: LKML Cc: x86@kernel.org, Peter Zijlstra , Bin Yang , Dave Hansen , Mark Gross Subject: [patch V2 05/10] x86/mm/cpa: Add large page preservation statistics References: <20180914130917.155416208@linutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline; filename=x86-mm-cpa--Add-large-page-preservation-statistics.patch Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The large page preservation mechanism is just magic and provides no information at all. Add optional statistic output in debugfs so the magic can be evaluated. Defaults is off. Output: 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 Signed-off-by: Thomas Gleixner --- arch/x86/Kconfig | 8 +++ arch/x86/mm/pageattr.c | 99 ++++++++++++++++++++++++++++++++++++++++++++++++- 2 files changed, 105 insertions(+), 2 deletions(-) --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -1495,6 +1495,14 @@ config X86_DIRECT_GBPAGES supports them), so don't confuse the user by printing that we have them enabled. +config X86_CPA_STATISTICS + bool "Enable statistic for Change Page Attribute" + depends on DEBUG_FS + ---help--- + Expose statistics about the Change Page Attribute mechanims, which + helps to determine the effectivness of preserving large and huge + page mappings when mapping protections are changed. + config ARCH_HAS_MEM_ENCRYPT def_bool y --- a/arch/x86/mm/pageattr.c +++ b/arch/x86/mm/pageattr.c @@ -101,6 +101,95 @@ void arch_report_meminfo(struct seq_file static inline void split_page_count(int level) { } #endif +#ifdef CONFIG_X86_CPA_STATISTICS + +static unsigned long cpa_1g_checked; +static unsigned long cpa_1g_sameprot; +static unsigned long cpa_1g_preserved; +static unsigned long cpa_2m_checked; +static unsigned long cpa_2m_sameprot; +static unsigned long cpa_2m_preserved; +static unsigned long cpa_4k_checked; +static unsigned long cpa_4k_install; + +static inline void cpa_inc_1g_checked(void) +{ + cpa_1g_checked++; +} + +static inline void cpa_inc_2m_checked(void) +{ + cpa_2m_checked++; +} + +static inline void cpa_inc_4k_checked(void) +{ + cpa_4k_checked++; +} + +static inline void cpa_inc_4k_install(void) +{ + cpa_4k_install++; +} + +static inline void cpa_inc_lp_sameprot(int level) +{ + if (level == PG_LEVEL_1G) + cpa_1g_sameprot++; + else + cpa_2m_sameprot++; +} + +static inline void cpa_inc_lp_preserved(int level) +{ + if (level == PG_LEVEL_1G) + cpa_1g_preserved++; + else + cpa_2m_preserved++; +} + +static int cpastats_show(struct seq_file *m, void *p) +{ + seq_printf(m, "1G pages checked: %16lu\n", cpa_1g_checked); + seq_printf(m, "1G pages sameprot: %16lu\n", cpa_1g_sameprot); + seq_printf(m, "1G pages preserved: %16lu\n", cpa_1g_preserved); + seq_printf(m, "2M pages checked: %16lu\n", cpa_2m_checked); + seq_printf(m, "2M pages sameprot: %16lu\n", cpa_2m_sameprot); + seq_printf(m, "2M pages preserved: %16lu\n", cpa_2m_preserved); + seq_printf(m, "4K pages checked: %16lu\n", cpa_4k_checked); + seq_printf(m, "4K pages set-checked: %16lu\n", cpa_4k_install); + return 0; +} + +static int cpastats_open(struct inode *inode, struct file *file) +{ + return single_open(file, cpastats_show, NULL); +} + +static const struct file_operations cpastats_fops = { + .open = cpastats_open, + .read = seq_read, + .llseek = seq_lseek, + .release = single_release, +}; + +static int __init cpa_stats_init(void) +{ + debugfs_create_file("cpa_stats", S_IRUSR, arch_debugfs_dir, NULL, + &cpastats_fops); + return 0; +} +late_initcall(cpa_stats_init); +#else +static inline void cpa_inc_1g_checked(void) { } +static inline void cpa_inc_2m_checked(void) { } +static inline void cpa_inc_4k_checked(void) { } +static inline void cpa_inc_4k_install(void) { } +static inline void cpa_inc_lp_sameprot(int level) { } +static inline void cpa_inc_lp_preserved(int level) { } +#endif + + static inline int within(unsigned long addr, unsigned long start, unsigned long end) { @@ -660,10 +749,12 @@ static int __should_split_large_page(pte case PG_LEVEL_2M: old_prot = pmd_pgprot(*(pmd_t *)kpte); old_pfn = pmd_pfn(*(pmd_t *)kpte); + cpa_inc_2m_checked(); break; case PG_LEVEL_1G: old_prot = pud_pgprot(*(pud_t *)kpte); old_pfn = pud_pfn(*(pud_t *)kpte); + cpa_inc_1g_checked(); break; default: return -EINVAL; @@ -728,14 +819,16 @@ static int __should_split_large_page(pte for (i = 0, addr = lpaddr; i < numpages; i++, addr += PAGE_SIZE, pfn++) { pgprot_t chk_prot = static_protections(req_prot, addr, pfn, 1, CPA_DETECT); - + cpa_inc_4k_checked(); if (pgprot_val(chk_prot) != pgprot_val(new_prot)) return 1; } /* If there are no changes, return. */ - if (pgprot_val(new_prot) == pgprot_val(old_prot)) + if (pgprot_val(new_prot) == pgprot_val(old_prot)) { + cpa_inc_lp_sameprot(level); return 0; + } /* * Verify that the address is aligned and the number of pages @@ -748,6 +841,7 @@ static int __should_split_large_page(pte new_pte = pfn_pte(old_pfn, new_prot); __set_pmd_pte(kpte, address, new_pte); cpa->flags |= CPA_FLUSHTLB; + cpa_inc_lp_preserved(level); return 0; } @@ -1337,6 +1431,7 @@ static int __change_page_attr(struct cpa pgprot_val(new_prot) &= ~pgprot_val(cpa->mask_clr); pgprot_val(new_prot) |= pgprot_val(cpa->mask_set); + cpa_inc_4k_install(); new_prot = static_protections(new_prot, address, pfn, 1, CPA_PROTECT);