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bh=42pLyzKDZ/gxRKMRifq1wFLLa5fytpU5alp2iv0kz9I=; b=BJCkvEdNJY1LPJKNo2ifW17Cw9ONwcE7fcPunGmpT+nIcgP5WDsozeeiRk+9z68ZopXoxq FwOEV6XJ+ktAkFsZIRNlyIHnYYd28dYnuoGKyKAkYuH8ZIhiyGW7iXFLsQqDOwraQLEyjg xpFKwjJvKiwE3A9R0DlsV59z5MTopoc= X-MC-Unique: RltI-H2zPdu3Sn2IYGDW0g-1 From: Stefan Hajnoczi To: qemu-devel@nongnu.org Subject: [PATCH v3 1/3] memory: add readonly support to memory_region_init_ram_from_file() Date: Mon, 4 Jan 2021 17:13:18 +0000 Message-Id: <20210104171320.575838-2-stefanha@redhat.com> In-Reply-To: <20210104171320.575838-1-stefanha@redhat.com> References: <20210104171320.575838-1-stefanha@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 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=63.128.21.124; envelope-from=stefanha@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -29 X-Spam_score: -3.0 X-Spam_bar: --- X-Spam_report: (-3.0 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.243, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H4=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: Xiao Guangrong , "Michael S. Tsirkin" , Julio Montes , Eduardo Habkost , 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" 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=A9 Reviewed-by: Igor Mammedov Reviewed-by: Liam Merwick Signed-off-by: Stefan Hajnoczi --- include/exec/memory.h | 2 ++ include/exec/ram_addr.h | 5 +++-- include/qemu/mmap-alloc.h | 2 ++ backends/hostmem-file.c | 2 +- softmmu/memory.c | 7 +++++-- softmmu/physmem.c | 18 +++++++++++------- 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 521d9901d7..c6ce74fb79 100644 --- a/include/exec/memory.h +++ b/include/exec/memory.h @@ -966,6 +966,7 @@ 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 @@ -978,6 +979,7 @@ 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 c6d2ef1d07..40b16609ab 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 40e1e5b3e3..e827692124 100644 --- a/backends/hostmem-file.c +++ b/backends/hostmem-file.c @@ -56,7 +56,7 @@ 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/softmmu/memory.c b/softmmu/memory.c index 333e1ed7b0..676c298b60 100644 --- a/softmmu/memory.c +++ b/softmmu/memory.c @@ -1587,15 +1587,18 @@ 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); if (err) { mr->size =3D int128_zero(); object_unparent(OBJECT(mr)); @@ -1618,7 +1621,7 @@ 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); if (err) { mr->size =3D int128_zero(); object_unparent(OBJECT(mr)); diff --git a/softmmu/physmem.c b/softmmu/physmem.c index 2cd1de4a2c..5753cfc39f 100644 --- a/softmmu/physmem.c +++ b/softmmu/physmem.c @@ -1398,6 +1398,7 @@ 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) { @@ -1408,7 +1409,7 @@ 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; @@ -1460,6 +1461,7 @@ 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) { @@ -1510,7 +1512,7 @@ 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, @@ -1942,7 +1944,7 @@ 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; @@ -1996,7 +1998,8 @@ 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; @@ -2015,18 +2018,19 @@ 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/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 f15234b5c0..cfe86553da 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 2.29.2