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bh=bKBHBoH9dGFt0R/uUkWH6Lh6oMUiq2Vl3Dy7wGj8CEU=; b=CtI2YZxSUb3h/1wtTJoVkkAo1Bac2iUDayRD6Y5lf45BqTWd2j10j3xAvxZzv66Qg8+WQA fRPcknlsEvGa1YCfHIWVmZj57/ue0Ztyz9k5PV07EYsZ2VK1+pjc89YukesYHqLS+AiR/k 11n7yK6yehY/21Z8+bUNVJ5iTJZaIC8= X-MC-Unique: KTbJwVvTOkeQE3nvKZPu3g-1 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 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 = 2020/09/16 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=20Mathieu-Daud=C3=83=C2=A9?= , 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. Acked-by: Michael S. Tsirkin Reviewed-by: Philippe Mathieu-Daud=C3=83=C2=A9 Signed-off-by: Stefan Hajnoczi Reviewed-by: Igor Mammedov Reviewed-by: Liam Merwick Tested-by: Liam Merwick --- 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); =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 a3b2e8209e..dffdf142e0 100644 --- a/backends/hostmem-file.c +++ b/backends/hostmem-file.c @@ -58,7 +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, 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) =20 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, =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; @@ -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"); } =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, @@ -2314,7 +2316,7 @@ 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; @@ -2368,7 +2370,8 @@ 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; @@ -2387,18 +2390,19 @@ 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 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 =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 Thu Mar 28 11:50:19 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=1600250664; cv=none; d=zohomail.com; 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Wed, 16 Sep 2020 09:52:14 +0000 (UTC) Received: from localhost (ovpn-115-47.ams2.redhat.com [10.36.115.47]) by smtp.corp.redhat.com (Postfix) with ESMTP id A976560BFA; Wed, 16 Sep 2020 09:52:07 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1600249936; 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=UgsgLUowiBqZlz5+WiOQFwOsVeKJ0sRt4MwusZZWNVI=; b=USJMFd8aeH1SEHIMAI5SR7WHcjDSRqtnDxWsagGWuDgLTLOkDo/ICYoiCdk9+wGoaF9Ehy Xdt7p0yJSNcMyy94NQccz3kdrGkC4x21tmBtzt0lQCGqKc+W3vCv8dURmr8YHxw/Y7BtQ1 Xi0ABDOaokR+RXwJeenhc4tKPMy65Bg= X-MC-Unique: 83ZCLrD9MBayvWt8Ww3O8g-1 From: Stefan Hajnoczi To: qemu-devel@nongnu.org Subject: [PATCH v2 2/3] hostmem-file: add readonly=on|off option Date: Wed, 16 Sep 2020 10:51:49 +0100 Message-Id: <20200916095150.755714-3-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 10.5.11.12 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 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=63.128.21.124; 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 02:35:56 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=20Mathieu-Daud=C3=A9?= , 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. Acked-by: Michael S. Tsirkin Reviewed-by: Philippe Mathieu-Daud=C3=A9 Signed-off-by: Stefan Hajnoczi Reviewed-by: Liam Merwick Tested-by: Liam Merwick --- 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 dffdf142e0..da585e4300 100644 --- a/backends/hostmem-file.c +++ b/backends/hostmem-file.c @@ -31,6 +31,7 @@ struct HostMemoryBackendFile { uint64_t align; bool discard_data; bool is_pmem; + bool readonly; }; =20 static void @@ -58,7 +59,7 @@ 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 } @@ -153,6 +154,26 @@ 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); @@ -184,6 +205,9 @@ 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 b0f020594e..3dfaaddd62 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 Thu Mar 28 11:50:19 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=1600250193; cv=none; d=zohomail.com; s=zohoarc; b=aztcd4QsMOEdkOeZ44FP+Xfe6SoWTMuKxawFctFnks0cJqy6WXow7odSWcm13kMkk6DINz1cIX46qTxK/r907Tf/QsQxjsTcclgmMm8rBd9cqaLeyRPlvfpt5Iz/oxB7/ubb81akCM0BezLHUtlXtZXyeGmL2vy0doUkbfwXF00= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=zohomail.com; s=zohoarc; t=1600250193; 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=MXsIGqRE07bfYc36CHCsPlQ1Vpqma7Ye5JadMeb6sv4=; b=KnwC4o7S62CM8L9bCJGB8M0PY4uxM65xP6NNqUCuZ17l7qVZQOe0X2gaoR1/btc5E9OT4GaIEbR9sJZk8tkqiRm3FBiKyAmYgIdYnM2UdPkI2vOp7ZboAr6Yo1efuZ3Z4dHJKaM8jhayu+8OHLVR7vMQ8FIFRxjPRtwFj0uoVws= ARC-Authentication-Results: i=1; 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Wed, 16 Sep 2020 05:52:22 -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-504-0jd0sEcGP2iZFE3-TL3QBQ-1; Wed, 16 Sep 2020 05:52:16 -0400 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id B5F48107464B; Wed, 16 Sep 2020 09:52:15 +0000 (UTC) Received: from localhost (ovpn-115-47.ams2.redhat.com [10.36.115.47]) by smtp.corp.redhat.com (Postfix) with ESMTP id 5A66260BFA; Wed, 16 Sep 2020 09:52:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1600249940; 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=MXsIGqRE07bfYc36CHCsPlQ1Vpqma7Ye5JadMeb6sv4=; b=f5hMZsOevlHDyIMCmCHNFqBXR8zypkKyMWrOwbrmnxajCadYP8ygkjW3NPAGYxTzOqgceh cXPxZ6spedp0KlkhvcZ6fE2jV2HqdAyn27ND/gFYWAWNHeNT6zaZKYxklWD+pAYhhgTPSi 2VEQDl65MGninETmBSOq34XRoCPzwPQ= X-MC-Unique: 0jd0sEcGP2iZFE3-TL3QBQ-1 From: Stefan Hajnoczi To: qemu-devel@nongnu.org Subject: [PATCH v2 3/3] nvdimm: honor -object memory-backend-file, readonly=on option Date: Wed, 16 Sep 2020 10:51:50 +0100 Message-Id: <20200916095150.755714-4-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 10.5.11.12 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=stefanha@redhat.com X-Mimecast-Spam-Score: 0.003 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=205.139.110.61; envelope-from=stefanha@redhat.com; helo=us-smtp-delivery-1.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/09/16 00:53:39 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_H2=-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=20Mathieu-Daud=C3=A9?= , 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. Acked-by: Michael S. Tsirkin Reviewed-by: Philippe Mathieu-Daud=C3=A9 Signed-off-by: Stefan Hajnoczi Reviewed-by: Liam Merwick Tested-by: Liam Merwick --- 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..06c2008107 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 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..848cd65917 100644 --- a/hw/mem/nvdimm.c +++ b/hw/mem/nvdimm.c @@ -146,6 +146,10 @@ static void nvdimm_prepare_memory_region(NVDIMMDevice = *nvdimm, Error **errp) return; } =20 + if (memory_region_is_rom(mr)) { + nvdimm->unarmed =3D true; /* this device is read-only */ + } + nvdimm->nvdimm_mr =3D g_new(MemoryRegion, 1); memory_region_init_alias(nvdimm->nvdimm_mr, OBJECT(dimm), "nvdimm-memory", mr, 0, pmem_size); --=20 2.26.2