From patchwork Wed Sep 16 09:51:48 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Stefan Hajnoczi X-Patchwork-Id: 273585 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=-9.6 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH, MAILING_LIST_MULTI, SIGNED_OFF_BY, 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 DBE5AC433E2 for ; Wed, 16 Sep 2020 10:02:34 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 6EED92076B for ; Wed, 16 Sep 2020 10:02:34 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="CtI2YZxS" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 6EED92076B Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:50944 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1kIUGn-0003ES-Jp for qemu-devel@archiver.kernel.org; Wed, 16 Sep 2020 06:02:33 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:53756) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1kIU6o-0005z0-9N for qemu-devel@nongnu.org; Wed, 16 Sep 2020 05:52:14 -0400 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:36447) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_CBC_SHA1:256) (Exim 4.90_1) (envelope-from ) id 1kIU6m-0000dX-1N for qemu-devel@nongnu.org; Wed, 16 Sep 2020 05:52:13 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1600249931; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=bKBHBoH9dGFt0R/uUkWH6Lh6oMUiq2Vl3Dy7wGj8CEU=; b=CtI2YZxSUb3h/1wtTJoVkkAo1Bac2iUDayRD6Y5lf45BqTWd2j10j3xAvxZzv66Qg8+WQA fRPcknlsEvGa1YCfHIWVmZj57/ue0Ztyz9k5PV07EYsZ2VK1+pjc89YukesYHqLS+AiR/k 11n7yK6yehY/21Z8+bUNVJ5iTJZaIC8= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-587-KTbJwVvTOkeQE3nvKZPu3g-1; Wed, 16 Sep 2020 05:52:07 -0400 X-MC-Unique: KTbJwVvTOkeQE3nvKZPu3g-1 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.phx2.redhat.com [10.5.11.16]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 47E3F1074657; Wed, 16 Sep 2020 09:52:06 +0000 (UTC) Received: from localhost (ovpn-115-47.ams2.redhat.com [10.36.115.47]) by smtp.corp.redhat.com (Postfix) with ESMTP id EFFCA1C4; Wed, 16 Sep 2020 09:51:58 +0000 (UTC) From: Stefan Hajnoczi To: qemu-devel@nongnu.org Subject: [PATCH v2 1/3] memory: add readonly support to memory_region_init_ram_from_file() Date: Wed, 16 Sep 2020 10:51:48 +0100 Message-Id: <20200916095150.755714-2-stefanha@redhat.com> In-Reply-To: <20200916095150.755714-1-stefanha@redhat.com> References: <20200916095150.755714-1-stefanha@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=stefanha@redhat.com X-Mimecast-Spam-Score: 0.002 X-Mimecast-Originator: redhat.com Received-SPF: pass client-ip=216.205.24.124; envelope-from=stefanha@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/09/16 02:16:02 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] X-Spam_score_int: -50 X-Spam_score: -5.1 X-Spam_bar: ----- X-Spam_report: (-5.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-2.999, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H5=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Eduardo Habkost , "Michael S. Tsirkin" , Julio Montes , Xiao Guangrong , eric.g.ernst@gmail.com, Stefan Hajnoczi , Igor Mammedov , Paolo Bonzini , =?utf-8?q?Philippe_Mathieu-Daud=C3=83?= =?utf-8?b?wqk=?= , Richard Henderson Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" There is currently no way to open(O_RDONLY) and mmap(PROT_READ) when creating a memory region from a file. This functionality is needed since the underlying host file may not allow writing. Add a bool readonly argument to memory_region_init_ram_from_file() and the APIs it calls. Extend memory_region_init_ram_from_file() rather than introducing a memory_region_init_rom_from_file() API so that callers can easily make a choice between read/write and read-only at runtime without calling different APIs. No new RAMBlock flag is introduced for read-only because it's unclear whether RAMBlocks need to know that they are read-only. Pass a bool readonly argument instead. Both of these design decisions can be changed in the future. It just seemed like the simplest approach to me. Acked-by: Michael S. Tsirkin Reviewed-by: Philippe Mathieu-Daudé Signed-off-by: Stefan Hajnoczi Reviewed-by: Igor Mammedov --- include/exec/memory.h | 2 ++ include/exec/ram_addr.h | 5 +++-- include/qemu/mmap-alloc.h | 2 ++ backends/hostmem-file.c | 2 +- exec.c | 18 +++++++++++------- softmmu/memory.c | 7 +++++-- util/mmap-alloc.c | 10 ++++++---- util/oslib-posix.c | 2 +- 8 files changed, 31 insertions(+), 17 deletions(-) diff --git a/include/exec/memory.h b/include/exec/memory.h index f1bb2a7df5..a81fa26165 100644 --- a/include/exec/memory.h +++ b/include/exec/memory.h @@ -879,6 +879,7 @@ void memory_region_init_resizeable_ram(MemoryRegion *mr, * - RAM_PMEM: the memory is persistent memory * Other bits are ignored now. * @path: the path in which to allocate the RAM. + * @readonly: true to open @path for reading, false for read/write. * @errp: pointer to Error*, to store an error if it happens. * * Note that this function does not do anything to cause the data in the @@ -891,6 +892,7 @@ void memory_region_init_ram_from_file(MemoryRegion *mr, uint64_t align, uint32_t ram_flags, const char *path, + bool readonly, Error **errp); /** diff --git a/include/exec/ram_addr.h b/include/exec/ram_addr.h index 3ef729a23c..2a0360a0f2 100644 --- a/include/exec/ram_addr.h +++ b/include/exec/ram_addr.h @@ -110,6 +110,7 @@ long qemu_maxrampagesize(void); * - RAM_PMEM: the backend @mem_path or @fd is persistent memory * Other bits are ignored. * @mem_path or @fd: specify the backing file or device + * @readonly: true to open @path for reading, false for read/write. * @errp: pointer to Error*, to store an error if it happens * * Return: @@ -118,9 +119,9 @@ long qemu_maxrampagesize(void); */ RAMBlock *qemu_ram_alloc_from_file(ram_addr_t size, MemoryRegion *mr, uint32_t ram_flags, const char *mem_path, - Error **errp); + bool readonly, Error **errp); RAMBlock *qemu_ram_alloc_from_fd(ram_addr_t size, MemoryRegion *mr, - uint32_t ram_flags, int fd, + uint32_t ram_flags, int fd, bool readonly, Error **errp); RAMBlock *qemu_ram_alloc_from_ptr(ram_addr_t size, void *host, diff --git a/include/qemu/mmap-alloc.h b/include/qemu/mmap-alloc.h index e786266b92..8b7a5c70f3 100644 --- a/include/qemu/mmap-alloc.h +++ b/include/qemu/mmap-alloc.h @@ -14,6 +14,7 @@ size_t qemu_mempath_getpagesize(const char *mem_path); * @size: the number of bytes to be mmaped * @align: if not zero, specify the alignment of the starting mapping address; * otherwise, the alignment in use will be determined by QEMU. + * @readonly: true for a read-only mapping, false for read/write. * @shared: map has RAM_SHARED flag. * @is_pmem: map has RAM_PMEM flag. * @@ -24,6 +25,7 @@ size_t qemu_mempath_getpagesize(const char *mem_path); void *qemu_ram_mmap(int fd, size_t size, size_t align, + bool readonly, bool shared, bool is_pmem); diff --git a/backends/hostmem-file.c b/backends/hostmem-file.c index a3b2e8209e..dffdf142e0 100644 --- a/backends/hostmem-file.c +++ b/backends/hostmem-file.c @@ -58,7 +58,7 @@ file_backend_memory_alloc(HostMemoryBackend *backend, Error **errp) backend->size, fb->align, (backend->share ? RAM_SHARED : 0) | (fb->is_pmem ? RAM_PMEM : 0), - fb->mem_path, errp); + fb->mem_path, false, errp); g_free(name); #endif } diff --git a/exec.c b/exec.c index e34b602bdf..f1e82dad7a 100644 --- a/exec.c +++ b/exec.c @@ -1770,6 +1770,7 @@ static int64_t get_file_align(int fd) static int file_ram_open(const char *path, const char *region_name, + bool readonly, bool *created, Error **errp) { @@ -1780,7 +1781,7 @@ static int file_ram_open(const char *path, *created = false; for (;;) { - fd = open(path, O_RDWR); + fd = open(path, readonly ? O_RDONLY : O_RDWR); if (fd >= 0) { /* @path names an existing file, use it */ break; @@ -1832,6 +1833,7 @@ static int file_ram_open(const char *path, static void *file_ram_alloc(RAMBlock *block, ram_addr_t memory, int fd, + bool readonly, bool truncate, Error **errp) { @@ -1882,7 +1884,7 @@ static void *file_ram_alloc(RAMBlock *block, perror("ftruncate"); } - area = qemu_ram_mmap(fd, memory, block->mr->align, + area = qemu_ram_mmap(fd, memory, block->mr->align, readonly, block->flags & RAM_SHARED, block->flags & RAM_PMEM); if (area == MAP_FAILED) { error_setg_errno(errp, errno, @@ -2314,7 +2316,7 @@ static void ram_block_add(RAMBlock *new_block, Error **errp, bool shared) #ifdef CONFIG_POSIX RAMBlock *qemu_ram_alloc_from_fd(ram_addr_t size, MemoryRegion *mr, - uint32_t ram_flags, int fd, + uint32_t ram_flags, int fd, bool readonly, Error **errp) { RAMBlock *new_block; @@ -2368,7 +2370,8 @@ RAMBlock *qemu_ram_alloc_from_fd(ram_addr_t size, MemoryRegion *mr, new_block->used_length = size; new_block->max_length = size; new_block->flags = ram_flags; - new_block->host = file_ram_alloc(new_block, size, fd, !file_size, errp); + new_block->host = file_ram_alloc(new_block, size, fd, readonly, + !file_size, errp); if (!new_block->host) { g_free(new_block); return NULL; @@ -2387,18 +2390,19 @@ RAMBlock *qemu_ram_alloc_from_fd(ram_addr_t size, MemoryRegion *mr, RAMBlock *qemu_ram_alloc_from_file(ram_addr_t size, MemoryRegion *mr, uint32_t ram_flags, const char *mem_path, - Error **errp) + bool readonly, Error **errp) { int fd; bool created; RAMBlock *block; - fd = file_ram_open(mem_path, memory_region_name(mr), &created, errp); + fd = file_ram_open(mem_path, memory_region_name(mr), readonly, &created, + errp); if (fd < 0) { return NULL; } - block = qemu_ram_alloc_from_fd(size, mr, ram_flags, fd, errp); + block = qemu_ram_alloc_from_fd(size, mr, ram_flags, fd, readonly, errp); if (!block) { if (created) { unlink(mem_path); diff --git a/softmmu/memory.c b/softmmu/memory.c index d030eb6f7c..1b0d1d42c6 100644 --- a/softmmu/memory.c +++ b/softmmu/memory.c @@ -1553,15 +1553,18 @@ void memory_region_init_ram_from_file(MemoryRegion *mr, uint64_t align, uint32_t ram_flags, const char *path, + bool readonly, Error **errp) { Error *err = NULL; memory_region_init(mr, owner, name, size); mr->ram = true; + mr->readonly = readonly; mr->terminates = true; mr->destructor = memory_region_destructor_ram; mr->align = align; - mr->ram_block = qemu_ram_alloc_from_file(size, mr, ram_flags, path, &err); + mr->ram_block = qemu_ram_alloc_from_file(size, mr, ram_flags, path, + readonly, &err); mr->dirty_log_mask = tcg_enabled() ? (1 << DIRTY_MEMORY_CODE) : 0; if (err) { mr->size = int128_zero(); @@ -1585,7 +1588,7 @@ void memory_region_init_ram_from_fd(MemoryRegion *mr, mr->destructor = memory_region_destructor_ram; mr->ram_block = qemu_ram_alloc_from_fd(size, mr, share ? RAM_SHARED : 0, - fd, &err); + fd, false, &err); mr->dirty_log_mask = tcg_enabled() ? (1 << DIRTY_MEMORY_CODE) : 0; if (err) { mr->size = int128_zero(); diff --git a/util/mmap-alloc.c b/util/mmap-alloc.c index 27dcccd8ec..890fda6a35 100644 --- a/util/mmap-alloc.c +++ b/util/mmap-alloc.c @@ -85,9 +85,11 @@ size_t qemu_mempath_getpagesize(const char *mem_path) void *qemu_ram_mmap(int fd, size_t size, size_t align, + bool readonly, bool shared, bool is_pmem) { + int prot; int flags; int map_sync_flags = 0; int guardfd; @@ -146,8 +148,9 @@ void *qemu_ram_mmap(int fd, offset = QEMU_ALIGN_UP((uintptr_t)guardptr, align) - (uintptr_t)guardptr; - ptr = mmap(guardptr + offset, size, PROT_READ | PROT_WRITE, - flags | map_sync_flags, fd, 0); + prot = PROT_READ | (readonly ? 0 : PROT_WRITE); + + ptr = mmap(guardptr + offset, size, prot, flags | map_sync_flags, fd, 0); if (ptr == MAP_FAILED && map_sync_flags) { if (errno == ENOTSUP) { @@ -171,8 +174,7 @@ void *qemu_ram_mmap(int fd, * if map failed with MAP_SHARED_VALIDATE | MAP_SYNC, * we will remove these flags to handle compatibility. */ - ptr = mmap(guardptr + offset, size, PROT_READ | PROT_WRITE, - flags, fd, 0); + ptr = mmap(guardptr + offset, size, prot, flags, fd, 0); } if (ptr == MAP_FAILED) { diff --git a/util/oslib-posix.c b/util/oslib-posix.c index ad8001a4ad..236b3a88c1 100644 --- a/util/oslib-posix.c +++ b/util/oslib-posix.c @@ -227,7 +227,7 @@ void *qemu_memalign(size_t alignment, size_t size) void *qemu_anon_ram_alloc(size_t size, uint64_t *alignment, bool shared) { size_t align = QEMU_VMALLOC_ALIGN; - void *ptr = qemu_ram_mmap(-1, size, align, shared, false); + void *ptr = qemu_ram_mmap(-1, size, align, false, shared, false); if (ptr == MAP_FAILED) { return NULL;