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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 90510C46467 for ; Fri, 20 Jan 2023 05:02:11 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230327AbjATFCK (ORCPT ); Fri, 20 Jan 2023 00:02:10 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58632 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230230AbjATFBy (ORCPT ); Fri, 20 Jan 2023 00:01:54 -0500 Received: from mga18.intel.com (mga18.intel.com [134.134.136.126]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C2EB2CC5D7; Thu, 19 Jan 2023 20:49:26 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1674190166; x=1705726166; h=from:to:cc:subject:date:message-id; bh=MRaoQHl13vbKfYUOZLICSPqZK23aH07qLJtCBzzV2wo=; b=C0C1I5xriEW++3c7rTYfu8PvTco+aE9ZIw4uRGOpK7Po0JoCUq2CygcZ naW3meiQVIvchc+aH4ndt8TQTnJZ2gN6eGfSuZ1gwue4uboW3m6LJy/o2 u6V2SVUTA70slAS3yQsvniuJJHm/zzOcba9PXZTmLBo9G/ydv33JqoLTp Emw1x5xbECOEiFZce95DBT8BsZqZHn7iMRC4eiFepDZ5Ll0OB36pax5M2 MdUWuQYC3TCK2JvFAlEcrSqpNZIG2nBD19QOkkRj8wqquKwuMNIowZycS gsQmwJ9EOY5On/j+gOe+r6ZCOVbzyJb7E4v4uc1wk7Pno3o0qmrTM6VMe A==; X-IronPort-AV: E=McAfee;i="6500,9779,10595"; a="309042726" X-IronPort-AV: E=Sophos;i="5.97,230,1669104000"; d="scan'208";a="309042726" Received: from fmsmga007.fm.intel.com ([10.253.24.52]) by orsmga106.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 19 Jan 2023 15:52:13 -0800 X-IronPort-AV: E=McAfee;i="6500,9779,10595"; a="662317599" X-IronPort-AV: E=Sophos;i="5.97,230,1669104000"; d="scan'208";a="662317599" Received: from hossain3-mobl.amr.corp.intel.com (HELO rpedgeco-desk.amr.corp.intel.com) ([10.252.128.187]) by fmsmga007-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 19 Jan 2023 15:52:12 -0800 From: Rick Edgecombe To: tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com, hpa@zytor.com, x86@kernel.org, rafael@kernel.org, pavel@ucw.cz, len.brown@intel.com, rppt@kernel.org, peterz@infradead.org, luto@kernel.org Cc: rick.p.edgecombe@intel.com, linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org Subject: [PATCH v3] x86/hibernate: Use fixmap for saving unmapped pages Date: Thu, 19 Jan 2023 15:51:45 -0800 Message-Id: <20230119235145.22740-1-rick.p.edgecombe@intel.com> X-Mailer: git-send-email 2.17.1 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hibernate uses the direct map to read memory it saves to disk. Since sometimes pages are not accessible on the direct map ("not present" on x86), it has special case logic to temporarily make a page present. On x86 these direct map addresses can be mapped at various page sizes, but the logic works ok as long as the not present pages are always mapped as PAGE_SIZE such that they don't require a split to map the region as present. If the address was mapped not present by a larger page size, the split may fail and hibernate would then try to read an address mapped not present. Today on x86 there are no known cases of this (huge not present pages on the direct map), but it has come up from time to time when developing things that operate on the direct map. It blocked making VM_FLUSH_RESET_PERMS support huge vmalloc when that came up, and also has been a complication for various direct map protection efforts. This dependency is also pretty hidden and easily missed by people poking at the direct map. For this reason, there are warnings in place to complain but not handle this scenario. One way to make this more robust would be to create some new CPA functionality that can know to map and reset the whole huge page in the case of trying to map a subpage. But for simplicity and smaller code, just make x86 hibernate have its own fixmap PTE that it can use to point to 4k pages when it encounters an unmapped direct map page. So create arch breakouts for hibernate_map_page() and hibernate_unmap_page() so that the mapping of unmapped pages can be off the direct map. Change hibernate_map_page() to return an address, and implement an arch breakout on x86 on that uses the fixmap. Since now hibernate_map_page() can return a value, have it return NULL when the page fails to map, and have safe_copy_page() skip copying the page if it fails to map. The existing behavior should crash in this case, so this way there is a chance the system would be recoverable. Use __weak for the arch breakout because there is not a suitable arch specific header to use the #define method. Signed-off-by: Rick Edgecombe --- v3: - Switch from hib_copy_page() breakout to hibernate_un/map_page() breakouts. - Since there is an error to use now, skip copying for unmappable pages v2: - Rebase arch/x86/include/asm/fixmap.h | 3 +++ arch/x86/power/hibernate.c | 12 ++++++++++++ include/linux/suspend.h | 2 ++ kernel/power/snapshot.c | 22 ++++++++++++++-------- 4 files changed, 31 insertions(+), 8 deletions(-) diff --git a/arch/x86/include/asm/fixmap.h b/arch/x86/include/asm/fixmap.h index d0dcefb5cc59..0fceed9a4152 100644 --- a/arch/x86/include/asm/fixmap.h +++ b/arch/x86/include/asm/fixmap.h @@ -108,6 +108,9 @@ enum fixed_addresses { #ifdef CONFIG_PARAVIRT_XXL FIX_PARAVIRT_BOOTMAP, #endif +#ifdef CONFIG_HIBERNATION + FIX_HIBERNATE, +#endif #ifdef CONFIG_ACPI_APEI_GHES /* Used for GHES mapping from assorted contexts */ diff --git a/arch/x86/power/hibernate.c b/arch/x86/power/hibernate.c index 6f955eb1e163..e7cde7cd529d 100644 --- a/arch/x86/power/hibernate.c +++ b/arch/x86/power/hibernate.c @@ -147,6 +147,18 @@ int arch_hibernation_header_restore(void *addr) return 0; } +long *hibernate_map_page(struct page *page) +{ + set_fixmap(FIX_HIBERNATE, page_to_phys(page)); + __flush_tlb_all(); + return (long *)fix_to_virt(FIX_HIBERNATE); +} + +void hibernate_unmap_page(struct page *page) +{ + clear_fixmap(FIX_HIBERNATE); +} + int relocate_restore_code(void) { pgd_t *pgd; diff --git a/include/linux/suspend.h b/include/linux/suspend.h index cfe19a028918..a6c3f7dac9e1 100644 --- a/include/linux/suspend.h +++ b/include/linux/suspend.h @@ -447,6 +447,8 @@ extern bool hibernation_available(void); asmlinkage int swsusp_save(void); extern struct pbe *restore_pblist; int pfn_is_nosave(unsigned long pfn); +long *hibernate_map_page(struct page *page); +void hibernate_unmap_page(struct page *page); int hibernate_quiet_exec(int (*func)(void *data), void *data); #else /* CONFIG_HIBERNATION */ diff --git a/kernel/power/snapshot.c b/kernel/power/snapshot.c index cd8b7b35f1e8..8cc16114da75 100644 --- a/kernel/power/snapshot.c +++ b/kernel/power/snapshot.c @@ -83,19 +83,18 @@ static inline void hibernate_restore_unprotect_page(void *page_address) {} * It is still worth to have a warning here if something changes and this * will no longer be the case. */ -static inline void hibernate_map_page(struct page *page) +long * __weak hibernate_map_page(struct page *page) { if (IS_ENABLED(CONFIG_ARCH_HAS_SET_DIRECT_MAP)) { - int ret = set_direct_map_default_noflush(page); - - if (ret) - pr_warn_once("Failed to remap page\n"); + if (set_direct_map_default_noflush(page)) + return NULL; } else { debug_pagealloc_map_pages(page, 1); } + return page_address(page); } -static inline void hibernate_unmap_page(struct page *page) +void __weak hibernate_unmap_page(struct page *page) { if (IS_ENABLED(CONFIG_ARCH_HAS_SET_DIRECT_MAP)) { unsigned long addr = (unsigned long)page_address(page); @@ -1394,8 +1393,15 @@ static void safe_copy_page(void *dst, struct page *s_page) if (kernel_page_present(s_page)) { do_copy_page(dst, page_address(s_page)); } else { - hibernate_map_page(s_page); - do_copy_page(dst, page_address(s_page)); + long *src = hibernate_map_page(s_page); + + if (!src) { + pr_warn_once("Failed to remap page\n"); + return; + } + + do_copy_page(dst, src); + hibernate_unmap_page(s_page); } } -- 2.17.1