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=-20.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING,SPF_HELO_NONE,SPF_PASS 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 61751C433E6 for ; Wed, 17 Mar 2021 22:16:00 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0D80A64F5E for ; Wed, 17 Mar 2021 22:15:59 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229549AbhCQWP1 (ORCPT ); Wed, 17 Mar 2021 18:15:27 -0400 Received: from mail.kernel.org ([198.145.29.99]:52394 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230330AbhCQWPR (ORCPT ); Wed, 17 Mar 2021 18:15:17 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 1C21E64F18; Wed, 17 Mar 2021 22:15:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1616019316; bh=ihk5AIsrQnwgOCNfB8cAVpGn1PrLIbOL3j4EE96RvoE=; h=Date:From:To:Subject:From; b=xupGhPA7QHD2+KcMWpdf7iMzbvGjDpEK9W4OEo/V4L7cTGqOHf1a3DrOOSViuHo2Z TOkmS57ecdzRQTEuq5OvjVt/zybYBzLv2X/71BJoVWqoAQpeWlkyW8TSD6DXfxnlWP o68TFc8Q/IU2A1QdeaCX2ryG1X6p+BmHBbSvYDgE= Date: Wed, 17 Mar 2021 15:15:12 -0700 From: akpm@linux-foundation.org To: arnd@arndb.de, bp@alien8.de, catalin.marinas@arm.com, cl@linux.com, dan.j.williams@intel.com, dave.hansen@linux.intel.com, david@redhat.com, elena.reshetova@intel.com, guro@fb.com, hagen@jauu.net, hpa@zytor.com, jejb@linux.ibm.com, kirill@shutemov.name, luto@kernel.org, mark.rutland@arm.com, mingo@redhat.com, mm-commits@vger.kernel.org, mtk.manpages@gmail.com, palmer@dabbelt.com, palmerdabbelt@google.com, paul.walmsley@sifive.com, peterz@infradead.org, rick.p.edgecombe@intel.com, rppt@linux.ibm.com, shakeelb@google.com, shuah@kernel.org, tglx@linutronix.de, tycho@tycho.ws, viro@zeniv.linux.org.uk, will@kernel.org, willy@infradead.org Subject: + mm-add-definition-of-pmd_page_order.patch added to -mm tree Message-ID: <20210317221512.A39Ft3LQk%akpm@linux-foundation.org> User-Agent: s-nail v14.8.16 Precedence: bulk Reply-To: linux-kernel@vger.kernel.org List-ID: X-Mailing-List: mm-commits@vger.kernel.org The patch titled Subject: mm: add definition of PMD_PAGE_ORDER has been added to the -mm tree. Its filename is mm-add-definition-of-pmd_page_order.patch This patch should soon appear at https://ozlabs.org/~akpm/mmots/broken-out/mm-add-definition-of-pmd_page_order.patch and later at https://ozlabs.org/~akpm/mmotm/broken-out/mm-add-definition-of-pmd_page_order.patch Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/process/submit-checklist.rst when testing your code *** The -mm tree is included into linux-next and is updated there every 3-4 working days ------------------------------------------------------ From: Mike Rapoport Subject: mm: add definition of PMD_PAGE_ORDER Patch series "mm: introduce memfd_secret system call to create "secret" memory areas", v18. This is an implementation of "secret" mappings backed by a file descriptor. The file descriptor backing secret memory mappings is created using a dedicated memfd_secret system call The desired protection mode for the memory is configured using flags parameter of the system call. The mmap() of the file descriptor created with memfd_secret() will create a "secret" memory mapping. The pages in that mapping will be marked as not present in the direct map and will be present only in the page table of the owning mm. Although normally Linux userspace mappings are protected from other users, such secret mappings are useful for environments where a hostile tenant is trying to trick the kernel into giving them access to other tenants mappings. Additionally, in the future the secret mappings may be used as a mean to protect guest memory in a virtual machine host. For demonstration of secret memory usage we've created a userspace library https://git.kernel.org/pub/scm/linux/kernel/git/jejb/secret-memory-preloader.git that does two things: the first is act as a preloader for openssl to redirect all the OPENSSL_malloc calls to secret memory meaning any secret keys get automatically protected this way and the other thing it does is expose the API to the user who needs it. We anticipate that a lot of the use cases would be like the openssl one: many toolkits that deal with secret keys already have special handling for the memory to try to give them greater protection, so this would simply be pluggable into the toolkits without any need for user application modification. Hiding secret memory mappings behind an anonymous file allows usage of the page cache for tracking pages allocated for the "secret" mappings as well as using address_space_operations for e.g. page migration callbacks. The anonymous file may be also used implicitly, like hugetlb files, to implement mmap(MAP_SECRET) and use the secret memory areas with "native" mm ABIs in the future. Removing of the pages from the direct map may cause its fragmentation on architectures that use large pages to map the physical memory which affects the system performance. However, the original Kconfig text for CONFIG_DIRECT_GBPAGES said that gigabyte pages in the direct map "... can improve the kernel's performance a tiny bit ..." (commit 00d1c5e05736 ("x86: add gbpages switches")) and the recent report [1] showed that "... although 1G mappings are a good default choice, there is no compelling evidence that it must be the only choice". Hence, it is sufficient to have secretmem disabled by default with the ability of a system administrator to enable it at boot time. In addition, there is also a long term goal to improve management of the direct map. [1] https://lore.kernel.org/linux-mm/213b4567-46ce-f116-9cdf-bbd0c884eb3c@linux.intel.com/ This patch (of 9): The definition of PMD_PAGE_ORDER denoting the number of base pages in the second-level leaf page is already used by DAX and maybe handy in other cases as well. Several architectures already have definition of PMD_ORDER as the size of second level page table, so to avoid conflict with these definitions use PMD_PAGE_ORDER name and update DAX respectively. Link: https://lkml.kernel.org/r/20210303162209.8609-1-rppt@kernel.org Link: https://lkml.kernel.org/r/20210303162209.8609-2-rppt@kernel.org Signed-off-by: Mike Rapoport Reviewed-by: David Hildenbrand Cc: Alexander Viro Cc: Andy Lutomirski Cc: Arnd Bergmann Cc: Borislav Petkov Cc: Catalin Marinas Cc: Christopher Lameter Cc: Dan Williams Cc: Dave Hansen Cc: Elena Reshetova Cc: "H. Peter Anvin" Cc: Ingo Molnar Cc: James Bottomley Cc: "Kirill A. Shutemov" Cc: Matthew Wilcox Cc: Mark Rutland Cc: Michael Kerrisk Cc: Palmer Dabbelt Cc: Paul Walmsley Cc: Peter Zijlstra Cc: Rick Edgecombe Cc: Roman Gushchin Cc: Shakeel Butt Cc: Shuah Khan Cc: Thomas Gleixner Cc: Tycho Andersen Cc: Will Deacon Cc: Hagen Paul Pfeifer Cc: Palmer Dabbelt Signed-off-by: Andrew Morton --- fs/dax.c | 11 ++++------- include/linux/pgtable.h | 3 +++ 2 files changed, 7 insertions(+), 7 deletions(-) --- a/fs/dax.c~mm-add-definition-of-pmd_page_order +++ a/fs/dax.c @@ -49,9 +49,6 @@ static inline unsigned int pe_order(enum #define PG_PMD_COLOUR ((PMD_SIZE >> PAGE_SHIFT) - 1) #define PG_PMD_NR (PMD_SIZE >> PAGE_SHIFT) -/* The order of a PMD entry */ -#define PMD_ORDER (PMD_SHIFT - PAGE_SHIFT) - static wait_queue_head_t wait_table[DAX_WAIT_TABLE_ENTRIES]; static int __init init_dax_wait_table(void) @@ -98,7 +95,7 @@ static bool dax_is_locked(void *entry) static unsigned int dax_entry_order(void *entry) { if (xa_to_value(entry) & DAX_PMD) - return PMD_ORDER; + return PMD_PAGE_ORDER; return 0; } @@ -1471,7 +1468,7 @@ static vm_fault_t dax_iomap_pmd_fault(st { struct vm_area_struct *vma = vmf->vma; struct address_space *mapping = vma->vm_file->f_mapping; - XA_STATE_ORDER(xas, &mapping->i_pages, vmf->pgoff, PMD_ORDER); + XA_STATE_ORDER(xas, &mapping->i_pages, vmf->pgoff, PMD_PAGE_ORDER); unsigned long pmd_addr = vmf->address & PMD_MASK; bool write = vmf->flags & FAULT_FLAG_WRITE; bool sync; @@ -1530,7 +1527,7 @@ static vm_fault_t dax_iomap_pmd_fault(st * entry is already in the array, for instance), it will return * VM_FAULT_FALLBACK. */ - entry = grab_mapping_entry(&xas, mapping, PMD_ORDER); + entry = grab_mapping_entry(&xas, mapping, PMD_PAGE_ORDER); if (xa_is_internal(entry)) { result = xa_to_internal(entry); goto fallback; @@ -1696,7 +1693,7 @@ dax_insert_pfn_mkwrite(struct vm_fault * if (order == 0) ret = vmf_insert_mixed_mkwrite(vmf->vma, vmf->address, pfn); #ifdef CONFIG_FS_DAX_PMD - else if (order == PMD_ORDER) + else if (order == PMD_PAGE_ORDER) ret = vmf_insert_pfn_pmd(vmf, pfn, FAULT_FLAG_WRITE); #endif else --- a/include/linux/pgtable.h~mm-add-definition-of-pmd_page_order +++ a/include/linux/pgtable.h @@ -28,6 +28,9 @@ #define USER_PGTABLES_CEILING 0UL #endif +/* Number of base pages in a second level leaf page */ +#define PMD_PAGE_ORDER (PMD_SHIFT - PAGE_SHIFT) + /* * A page table page can be thought of an array like this: pXd_t[PTRS_PER_PxD] * _ Patches currently in -mm which might be from rppt@linux.ibm.com are mm-add-definition-of-pmd_page_order.patch mmap-make-mlock_future_check-global.patch riscv-kconfig-make-direct-map-manipulation-options-depend-on-mmu.patch set_memory-allow-set_direct_map__noflush-for-multiple-pages.patch set_memory-allow-querying-whether-set_direct_map_-is-actually-enabled.patch mm-introduce-memfd_secret-system-call-to-create-secret-memory-areas.patch pm-hibernate-disable-when-there-are-active-secretmem-users.patch arch-mm-wire-up-memfd_secret-system-call-where-relevant.patch secretmem-test-add-basic-selftest-for-memfd_secret2.patch