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bh=v4bCT5klV7TAmFkWeExwY64Qx38yKbxZ0Xk60uu8O3s=; b=b6xCXXw8PgEBmE9qu7A05vY91ujgUvVucSZ5HnipWvSxuv9EkEiltaD2dTKgAxz/y31Vcx 314T0rSEdtHJVKz0zmdCCVMuXFcOAfa+yFQ7w6UOFoyX/CZRHvK2j2iaFJFcJwFSARJcm9 uZtorO/BvGX92FPBPhyja6Mj555dArQ= X-MC-Unique: XxT2BjVsMreIePY2Oc0e4g-1 From: Stefan Hajnoczi To: qemu-devel@nongnu.org Subject: [PATCH 1/3] memory: add readonly support to memory_region_init_ram_from_file() Date: Tue, 4 Aug 2020 11:12:42 +0100 Message-Id: <20200804101244.1283503-2-stefanha@redhat.com> In-Reply-To: <20200804101244.1283503-1-stefanha@redhat.com> References: <20200804101244.1283503-1-stefanha@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=stefanha@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Transfer-Encoding: quoted-printable Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; 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 = 2020/08/04 06:13:03 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] X-Spam_score_int: -13 X-Spam_score: -1.4 X-Spam_bar: - X-Spam_report: (-1.4 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-1, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, MIME_BASE64_TEXT=1.741, RCVD_IN_DNSWL_NONE=-0.0001, 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 , Stefan Hajnoczi , Paolo Bonzini , Igor Mammedov , Richard Henderson Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: "Qemu-devel" X-ZohoMail-DKIM: fail (Header signature does not verify) Content-Type: text/plain; charset="utf-8" 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. Signed-off-by: Stefan Hajnoczi Acked-by: Michael S. Tsirkin Reviewed-by: Philippe Mathieu-Daud=C3=83=C2=A9 --- 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 307e527835..1ae7b31e3a 100644 --- a/include/exec/memory.h +++ b/include/exec/memory.h @@ -884,6 +884,7 @@ 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 @@ -896,6 +897,7 @@ void memory_region_init_ram_from_file(MemoryRegion *mr, uint64_t align, uint32_t ram_flags, const char *path, + bool readonly, Error **errp); =20 /** 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 mem= ory * 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_pat= h, - 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); =20 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 add= ress; * 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); =20 diff --git a/backends/hostmem-file.c b/backends/hostmem-file.c index 5b819020b4..37c70acfe2 100644 --- a/backends/hostmem-file.c +++ b/backends/hostmem-file.c @@ -57,7 +57,7 @@ file_backend_memory_alloc(HostMemoryBackend *backend, Err= or **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 6f381f98e2..5874e999ab 100644 --- a/exec.c +++ b/exec.c @@ -1769,6 +1769,7 @@ static int64_t get_file_align(int fd) =20 static int file_ram_open(const char *path, const char *region_name, + bool readonly, bool *created, Error **errp) { @@ -1779,7 +1780,7 @@ static int file_ram_open(const char *path, =20 *created =3D false; for (;;) { - fd =3D open(path, O_RDWR); + fd =3D open(path, readonly ? O_RDONLY : O_RDWR); if (fd >=3D 0) { /* @path names an existing file, use it */ break; @@ -1831,6 +1832,7 @@ 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) { @@ -1881,7 +1883,7 @@ static void *file_ram_alloc(RAMBlock *block, perror("ftruncate"); } =20 - area =3D qemu_ram_mmap(fd, memory, block->mr->align, + area =3D qemu_ram_mmap(fd, memory, block->mr->align, readonly, block->flags & RAM_SHARED, block->flags & RAM_PME= M); if (area =3D=3D MAP_FAILED) { error_setg_errno(errp, errno, @@ -2313,7 +2315,7 @@ static void ram_block_add(RAMBlock *new_block, Error = **errp, bool shared) =20 #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; @@ -2367,7 +2369,8 @@ RAMBlock *qemu_ram_alloc_from_fd(ram_addr_t size, Mem= oryRegion *mr, new_block->used_length =3D size; new_block->max_length =3D size; new_block->flags =3D ram_flags; - new_block->host =3D file_ram_alloc(new_block, size, fd, !file_size, er= rp); + new_block->host =3D file_ram_alloc(new_block, size, fd, readonly, + !file_size, errp); if (!new_block->host) { g_free(new_block); return NULL; @@ -2386,18 +2389,19 @@ RAMBlock *qemu_ram_alloc_from_fd(ram_addr_t size, M= emoryRegion *mr, =20 RAMBlock *qemu_ram_alloc_from_file(ram_addr_t size, MemoryRegion *mr, uint32_t ram_flags, const char *mem_pat= h, - Error **errp) + bool readonly, Error **errp) { int fd; bool created; RAMBlock *block; =20 - fd =3D file_ram_open(mem_path, memory_region_name(mr), &created, errp); + fd =3D file_ram_open(mem_path, memory_region_name(mr), readonly, &crea= ted, + errp); if (fd < 0) { return NULL; } =20 - block =3D qemu_ram_alloc_from_fd(size, mr, ram_flags, fd, errp); + block =3D qemu_ram_alloc_from_fd(size, mr, ram_flags, fd, readonly, er= rp); if (!block) { if (created) { unlink(mem_path); diff --git a/softmmu/memory.c b/softmmu/memory.c index af25987518..d228635bb3 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 =3D NULL; memory_region_init(mr, owner, name, size); mr->ram =3D true; + mr->readonly =3D readonly; mr->terminates =3D true; mr->destructor =3D memory_region_destructor_ram; mr->align =3D align; - mr->ram_block =3D qemu_ram_alloc_from_file(size, mr, ram_flags, path, = &err); + mr->ram_block =3D qemu_ram_alloc_from_file(size, mr, ram_flags, path, + readonly, &err); mr->dirty_log_mask =3D tcg_enabled() ? (1 << DIRTY_MEMORY_CODE) : 0; if (err) { mr->size =3D int128_zero(); @@ -1585,7 +1588,7 @@ void memory_region_init_ram_from_fd(MemoryRegion *mr, mr->destructor =3D memory_region_destructor_ram; mr->ram_block =3D qemu_ram_alloc_from_fd(size, mr, share ? RAM_SHARED : 0, - fd, &err); + fd, false, &err); mr->dirty_log_mask =3D tcg_enabled() ? (1 << DIRTY_MEMORY_CODE) : 0; if (err) { mr->size =3D 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 =3D 0; int guardfd; @@ -146,8 +148,9 @@ void *qemu_ram_mmap(int fd, =20 offset =3D QEMU_ALIGN_UP((uintptr_t)guardptr, align) - (uintptr_t)guar= dptr; =20 - ptr =3D mmap(guardptr + offset, size, PROT_READ | PROT_WRITE, - flags | map_sync_flags, fd, 0); + prot =3D PROT_READ | (readonly ? 0 : PROT_WRITE); + + ptr =3D mmap(guardptr + offset, size, prot, flags | map_sync_flags, fd= , 0); =20 if (ptr =3D=3D MAP_FAILED && map_sync_flags) { if (errno =3D=3D 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 =3D mmap(guardptr + offset, size, PROT_READ | PROT_WRITE, - flags, fd, 0); + ptr =3D mmap(guardptr + offset, size, prot, flags, fd, 0); } =20 if (ptr =3D=3D 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 =3D QEMU_VMALLOC_ALIGN; - void *ptr =3D qemu_ram_mmap(-1, size, align, shared, false); + void *ptr =3D qemu_ram_mmap(-1, size, align, false, shared, false); =20 if (ptr =3D=3D MAP_FAILED) { return NULL; --=20 2.26.2 From nobody Sat Apr 27 16:01:39 2024 Delivered-To: importer@patchew.org Authentication-Results: mx.zohomail.com; dkim=fail; spf=pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org; dmarc=fail(p=none dis=none) header.from=redhat.com ARC-Seal: i=1; a=rsa-sha256; t=1596536054; cv=none; d=zohomail.com; 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Tue, 4 Aug 2020 10:13:02 +0000 (UTC) Received: from localhost (ovpn-112-116.ams2.redhat.com [10.36.112.116]) by smtp.corp.redhat.com (Postfix) with ESMTP id 502B1282C9; Tue, 4 Aug 2020 10:13:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1596535985; 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=Y1fPzUvS6eRDBVdjttkwzUYOjrjLy0bRRDhpKDFS4P8=; b=cYa4wQ5zIvQsNuHZ2Ofiim85NbuLH9/ph9+z0Xdt4lbTqoATlfmXojEJ4Ok1wQPQJ+pFNu bfuZvViFzbwYdl/nz3QuYDOmyGFOGUSioI0KLw9eBk7dYqCN5ZZrCyjswJs7qWnJr+F2c3 2mjxgh117JJ6Gsi0SWXrEbTrzXHfRbk= X-MC-Unique: _dRAI42UPCOVtkVoGuBtbg-1 From: Stefan Hajnoczi To: qemu-devel@nongnu.org Subject: [PATCH 2/3] hostmem-file: add readonly=on|off option Date: Tue, 4 Aug 2020 11:12:43 +0100 Message-Id: <20200804101244.1283503-3-stefanha@redhat.com> In-Reply-To: <20200804101244.1283503-1-stefanha@redhat.com> References: <20200804101244.1283503-1-stefanha@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=stefanha@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Transfer-Encoding: quoted-printable Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Received-SPF: pass client-ip=207.211.31.120; envelope-from=stefanha@redhat.com; helo=us-smtp-1.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/08/04 01:28:11 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] X-Spam_score_int: -13 X-Spam_score: -1.4 X-Spam_bar: - X-Spam_report: (-1.4 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-1, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, MIME_BASE64_TEXT=1.741, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H4=-0.01, RCVD_IN_MSPIKE_WL=-0.01, 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 , Stefan Hajnoczi , Paolo Bonzini , Igor Mammedov , Richard Henderson Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: "Qemu-devel" X-ZohoMail-DKIM: fail (Header signature does not verify) Content-Type: text/plain; charset="utf-8" Let -object memory-backend-file work on read-only files when the readonly=3Don option is given. This can be used to share the contents of a file between multiple guests while preventing them from consuming Copy-on-Write memory if guests dirty the pages, for example. Signed-off-by: Stefan Hajnoczi Acked-by: Michael S. Tsirkin Reviewed-by: Philippe Mathieu-Daud=C3=A9 --- backends/hostmem-file.c | 26 +++++++++++++++++++++++++- qemu-options.hx | 5 ++++- 2 files changed, 29 insertions(+), 2 deletions(-) diff --git a/backends/hostmem-file.c b/backends/hostmem-file.c index 37c70acfe2..6bd5bf9b91 100644 --- a/backends/hostmem-file.c +++ b/backends/hostmem-file.c @@ -30,6 +30,7 @@ struct HostMemoryBackendFile { uint64_t align; bool discard_data; bool is_pmem; + bool readonly; }; =20 static void @@ -57,7 +58,7 @@ file_backend_memory_alloc(HostMemoryBackend *backend, Err= or **errp) backend->size, fb->align, (backend->share ? RAM_SHARED : 0) | (fb->is_pmem ? RAM_PMEM : 0), - fb->mem_path, false, errp); + fb->mem_path, fb->readonly, errp); g_free(name); #endif } @@ -152,6 +153,26 @@ static void file_memory_backend_set_pmem(Object *o, bo= ol value, Error **errp) fb->is_pmem =3D value; } =20 +static bool file_memory_backend_get_readonly(Object *o, Error **errp) +{ + return MEMORY_BACKEND_FILE(o)->readonly; +} + +static void file_memory_backend_set_readonly(Object *o, bool value, + Error **errp) +{ + HostMemoryBackend *backend =3D MEMORY_BACKEND(o); + HostMemoryBackendFile *fb =3D MEMORY_BACKEND_FILE(o); + + if (host_memory_backend_mr_inited(backend)) { + error_setg(errp, "cannot change property 'readonly' of %s.", + object_get_typename(o)); + return; + } + + fb->readonly =3D value; +} + static void file_backend_unparent(Object *obj) { HostMemoryBackend *backend =3D MEMORY_BACKEND(obj); @@ -183,6 +204,9 @@ file_backend_class_init(ObjectClass *oc, void *data) NULL, NULL); object_class_property_add_bool(oc, "pmem", file_memory_backend_get_pmem, file_memory_backend_set_pmem); + object_class_property_add_bool(oc, "readonly", + file_memory_backend_get_readonly, + file_memory_backend_set_readonly); } =20 static void file_backend_instance_finalize(Object *o) diff --git a/qemu-options.hx b/qemu-options.hx index 708583b4ce..d834e00b0d 100644 --- a/qemu-options.hx +++ b/qemu-options.hx @@ -4369,7 +4369,7 @@ SRST they are specified. Note that the 'id' property must be set. These objects are placed in the '/objects' path. =20 - ``-object memory-backend-file,id=3Did,size=3Dsize,mem-path=3Ddir,share= =3Don|off,discard-data=3Don|off,merge=3Don|off,dump=3Don|off,prealloc=3Don|= off,host-nodes=3Dhost-nodes,policy=3Ddefault|preferred|bind|interleave,alig= n=3Dalign`` + ``-object memory-backend-file,id=3Did,size=3Dsize,mem-path=3Ddir,share= =3Don|off,discard-data=3Don|off,merge=3Don|off,dump=3Don|off,prealloc=3Don|= off,host-nodes=3Dhost-nodes,policy=3Ddefault|preferred|bind|interleave,alig= n=3Dalign,readonly=3Don|off`` Creates a memory file backend object, which can be used to back the guest RAM with huge pages. =20 @@ -4452,6 +4452,9 @@ SRST 4.15) and the filesystem of ``mem-path`` mounted with DAX option. =20 + The ``readonly`` option specifies whether the backing file is open= ed + read-only or read-write (default). + ``-object memory-backend-ram,id=3Did,merge=3Don|off,dump=3Don|off,shar= e=3Don|off,prealloc=3Don|off,size=3Dsize,host-nodes=3Dhost-nodes,policy=3Dd= efault|preferred|bind|interleave`` Creates a memory backend object, which can be used to back the guest RAM. Memory backend objects offer more control than the --=20 2.26.2 From nobody Sat Apr 27 16:01:39 2024 Delivered-To: importer@patchew.org Authentication-Results: mx.zohomail.com; dkim=fail; spf=pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org; dmarc=fail(p=none dis=none) header.from=redhat.com ARC-Seal: i=1; a=rsa-sha256; t=1596536127; cv=none; d=zohomail.com; s=zohoarc; b=TV9hVctj7wGncflACGyk85pPAPn2wg39HfcO/h3IQNJHvrx/HX/6bGi1/CqdI0XSA6+WxZoNCupPumC0CC4uMe7e1mUPDayrwARHw9V4ArPSZZw3JA96Z5SzKOK3q9O9ji1H6C+HEnGADofq/pbGZoMJueIrLqsjEho7JQiinEY= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=zohomail.com; s=zohoarc; t=1596536127; h=Content-Type:Content-Transfer-Encoding:Cc:Date:From:In-Reply-To:List-Subscribe:List-Post:List-Id:List-Archive:List-Help:List-Unsubscribe:MIME-Version:Message-ID:References:Sender:Subject:To; bh=7tNdK7Ca4i2liwy+NdcizhRAuTPr3rRoZ97wATJpZj8=; b=Kh9JT02k05WriBkr37LXa2lEVInnXRhUxuJ/8b70ovlsakcz63sNIEtWSfJlByEzcZ0kUHlMsQSrT6Z/3F92y/6jW+vWnyB+zadVmMzxCox2hLzZewBpaWtCIw0gkogU71nxaPJATSKkTBsHsFuN8MCYGTf8CX7q1iHtRKxejz0= ARC-Authentication-Results: i=1; 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Tue, 04 Aug 2020 06:13:18 -0400 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-184-52Qk7QNyNm6APlJG1uG3Jg-1; Tue, 04 Aug 2020 06:13:13 -0400 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 905FB19057A2; Tue, 4 Aug 2020 10:13:12 +0000 (UTC) Received: from localhost (ovpn-112-116.ams2.redhat.com [10.36.112.116]) by smtp.corp.redhat.com (Postfix) with ESMTP id 283B671797; Tue, 4 Aug 2020 10:13:03 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1596535995; 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=7tNdK7Ca4i2liwy+NdcizhRAuTPr3rRoZ97wATJpZj8=; b=XKbvMmnFgdd+3kUFjxkQJMxlp+k/bUdTs2qFRrVly2vUaQUd+k2kJ4Yiiy8arBkzIr9eis c9be0xxK15cy1JfwisohuYejuwEj7/QhsUOEm2JRZ3dhTTpbiqboi2TYlOuEZLq/mSpBLK FelDQ7NkBKApj675xiRiA2Rsa1eozJo= X-MC-Unique: 52Qk7QNyNm6APlJG1uG3Jg-1 From: Stefan Hajnoczi To: qemu-devel@nongnu.org Subject: [PATCH 3/3] nvdimm: honor -object memory-backend-file, readonly=on option Date: Tue, 4 Aug 2020 11:12:44 +0100 Message-Id: <20200804101244.1283503-4-stefanha@redhat.com> In-Reply-To: <20200804101244.1283503-1-stefanha@redhat.com> References: <20200804101244.1283503-1-stefanha@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Transfer-Encoding: quoted-printable Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Received-SPF: pass client-ip=205.139.110.120; envelope-from=stefanha@redhat.com; helo=us-smtp-1.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/08/04 01:28:23 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] X-Spam_score_int: -13 X-Spam_score: -1.4 X-Spam_bar: - X-Spam_report: (-1.4 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-1, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, MIME_BASE64_TEXT=1.741, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H3=-0.01, RCVD_IN_MSPIKE_WL=-0.01, 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 , Stefan Hajnoczi , Paolo Bonzini , Igor Mammedov , Richard Henderson Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: "Qemu-devel" X-ZohoMail-DKIM: fail (Header signature does not verify) Content-Type: text/plain; charset="utf-8" Make it possible to present read-only files to the guest as "unarmed" NVDIMMs. The Linux NVDIMM device (/dev/pmemX) is read-only. Signed-off-by: Stefan Hajnoczi Acked-by: Michael S. Tsirkin Reviewed-by: Philippe Mathieu-Daud=C3=A9 --- docs/nvdimm.txt | 8 +++++++- hw/mem/nvdimm.c | 4 ++++ 2 files changed, 11 insertions(+), 1 deletion(-) diff --git a/docs/nvdimm.txt b/docs/nvdimm.txt index c2c6e441b3..c0b52de111 100644 --- a/docs/nvdimm.txt +++ b/docs/nvdimm.txt @@ -17,7 +17,7 @@ following command line options: =20 -machine pc,nvdimm -m $RAM_SIZE,slots=3D$N,maxmem=3D$MAX_SIZE - -object memory-backend-file,id=3Dmem1,share=3Don,mem-path=3D$PATH,size=3D= $NVDIMM_SIZE + -object memory-backend-file,id=3Dmem1,share=3Don,mem-path=3D$PATH,size=3D= $NVDIMM_SIZE,readonly=3Doff -device nvdimm,id=3Dnvdimm1,memdev=3Dmem1 =20 Where, @@ -42,6 +42,12 @@ Where, "share=3Doff", then guest writes won't be applied to the backend file and thus will be invisible to other guests. =20 + "readonly=3Don/off" controls whether the the file $PATH is opened read-= only or + read/write (default). "readonly=3Don" sets the ACPI NFIT NVDIMM Region = Mapping + Structure "NVDIMM State Flags" Bit 3 indicating that the device is "una= rmed" + and cannot accept persistent writes. Linux guest drivers set the device= to + read-only when this bit is present. + - "device nvdimm,id=3Dnvdimm1,memdev=3Dmem1" creates a virtual NVDIMM device whose storage is provided by above memory backend device. =20 diff --git a/hw/mem/nvdimm.c b/hw/mem/nvdimm.c index e1574bc07c..694223450e 100644 --- a/hw/mem/nvdimm.c +++ b/hw/mem/nvdimm.c @@ -151,6 +151,10 @@ static void nvdimm_prepare_memory_region(NVDIMMDevice = *nvdimm, Error **errp) "nvdimm-memory", mr, 0, pmem_size); memory_region_set_nonvolatile(nvdimm->nvdimm_mr, true); nvdimm->nvdimm_mr->align =3D align; + + if (memory_region_is_rom(mr)) { + nvdimm->unarmed =3D true; /* this device is read-only */ + } } =20 static MemoryRegion *nvdimm_md_get_memory_region(MemoryDeviceState *md, --=20 2.26.2