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bh=H7yynwKj61aAw1v1PQsbJxe999hYkP+QGDK+uQwND/g=; b=SiRb4ARn3UcaoHXBDj0EPh33iSAvCfZLEztGUpRKoxQrtzPJDBUafRkl/iQFi4DAvFNB2z n1D1W/RRn0NxebySmX8dExOJZc5oms2Bu+AMCg/bP9sAEnHnctFamWFhnOLaGEMIBva2lK ILkS9Gns3dFVcmMtd6Jwm5ItLCjt9aE= X-MC-Unique: mgDzZCCmPU6JhGuWvagheA-1 From: David Hildenbrand To: qemu-devel@nongnu.org Subject: [PATCH v6 07/15] util/mmap-alloc: Pass flags instead of separate bools to qemu_ram_mmap() Date: Wed, 21 Apr 2021 14:26:16 +0200 Message-Id: <20210421122624.12292-8-david@redhat.com> In-Reply-To: <20210421122624.12292-1-david@redhat.com> References: <20210421122624.12292-1-david@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=david@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=david@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -27 X-Spam_score: -2.8 X-Spam_bar: -- X-Spam_report: (-2.8 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, 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: Marcel Apfelbaum , Murilo Opsfelder Araujo , Eduardo Habkost , "Michael S. Tsirkin" , David Hildenbrand , Richard Henderson , "Dr. David Alan Gilbert" , Peter Xu , Greg Kurz , Stefan Hajnoczi , Igor Mammedov , Paolo Bonzini , =?UTF-8?q?Philippe=20Mathieu-Daud=C3=A9?= 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's pass flags instead of bools to prepare for passing other flags and update the documentation of qemu_ram_mmap(). Introduce new QEMU_MAP_ flags that abstract the mmap() PROT_ and MAP_ flag handling and simplify it. We expose only flags that are currently supported by qemu_ram_mmap(). Maybe, we'll see qemu_mmap() in the future as well that can implement these flags. Note: We don't use MAP_ flags as some flags (e.g., MAP_SYNC) are only defined for some systems and we want to always be able to identify these flags reliably inside qemu_ram_mmap() -- for example, to properly warn when some future flags are not available or effective on a system. Also, this way we can simplify PROT_ handling as well. Reviewed-by: Peter Xu Signed-off-by: David Hildenbrand Reviewed-by: Philippe Mathieu-Daud=C3=A9 --- include/qemu/mmap-alloc.h | 16 +++++++++------- include/qemu/osdep.h | 18 ++++++++++++++++++ softmmu/physmem.c | 8 +++++--- util/mmap-alloc.c | 15 ++++++++------- util/oslib-posix.c | 3 ++- 5 files changed, 42 insertions(+), 18 deletions(-) diff --git a/include/qemu/mmap-alloc.h b/include/qemu/mmap-alloc.h index 456ff87df1..90d0eee705 100644 --- a/include/qemu/mmap-alloc.h +++ b/include/qemu/mmap-alloc.h @@ -7,18 +7,22 @@ size_t qemu_fd_getpagesize(int fd); size_t qemu_mempath_getpagesize(const char *mem_path); =20 /** - * qemu_ram_mmap: mmap the specified file or device. + * qemu_ram_mmap: mmap anonymous memory, the specified file or device. + * + * mmap() abstraction to map guest RAM, simplifying flag handling, taking + * care of alignment requirements and installing guard pages. * * Parameters: * @fd: the file or the device to mmap * @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. + * @qemu_map_flags: QEMU_MAP_* flags * @map_offset: map starts at offset of map_offset from the start of fd * + * Internally, MAP_PRIVATE, MAP_ANONYMOUS and MAP_SHARED_VALIDATE are set + * implicitly based on other parameters. + * * Return: * On success, return a pointer to the mapped area. * On failure, return MAP_FAILED. @@ -26,9 +30,7 @@ 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, + uint32_t qemu_map_flags, off_t map_offset); =20 void qemu_ram_munmap(int fd, void *ptr, size_t size); diff --git a/include/qemu/osdep.h b/include/qemu/osdep.h index cb2a07e472..a96d6cb7ac 100644 --- a/include/qemu/osdep.h +++ b/include/qemu/osdep.h @@ -366,6 +366,24 @@ void *qemu_anon_ram_alloc(size_t size, uint64_t *align= , bool shared); void qemu_vfree(void *ptr); void qemu_anon_ram_free(void *ptr, size_t size); =20 +/* + * Abstraction of PROT_ and MAP_ flags as passed to mmap(), for example, + * consumed by qemu_ram_mmap(). + */ + +/* Map PROT_READ instead of PROT_READ | PROT_WRITE. */ +#define QEMU_MAP_READONLY (1 << 0) + +/* Use MAP_SHARED instead of MAP_PRIVATE. */ +#define QEMU_MAP_SHARED (1 << 1) + +/* + * Use MAP_SYNC | MAP_SHARED_VALIDATE if supported. Ignored without + * QEMU_MAP_SHARED. If mapping fails, warn and fallback to !QEMU_MAP_SYNC. + */ +#define QEMU_MAP_SYNC (1 << 2) + + #define QEMU_MADV_INVALID -1 =20 #if defined(CONFIG_MADVISE) diff --git a/softmmu/physmem.c b/softmmu/physmem.c index 11b45be271..2e8d1f47f0 100644 --- a/softmmu/physmem.c +++ b/softmmu/physmem.c @@ -1533,6 +1533,7 @@ static void *file_ram_alloc(RAMBlock *block, off_t offset, Error **errp) { + uint32_t qemu_map_flags; void *area; =20 block->page_size =3D qemu_fd_getpagesize(fd); @@ -1580,9 +1581,10 @@ static void *file_ram_alloc(RAMBlock *block, perror("ftruncate"); } =20 - area =3D qemu_ram_mmap(fd, memory, block->mr->align, readonly, - block->flags & RAM_SHARED, block->flags & RAM_PME= M, - offset); + qemu_map_flags =3D readonly ? QEMU_MAP_READONLY : 0; + qemu_map_flags |=3D (block->flags & RAM_SHARED) ? QEMU_MAP_SHARED : 0; + qemu_map_flags |=3D (block->flags & RAM_PMEM) ? QEMU_MAP_SYNC : 0; + area =3D qemu_ram_mmap(fd, memory, block->mr->align, qemu_map_flags, o= ffset); if (area =3D=3D MAP_FAILED) { error_setg_errno(errp, errno, "unable to map backing store for guest RAM"); diff --git a/util/mmap-alloc.c b/util/mmap-alloc.c index 0e2bd7bc0e..1ddc0e2a1e 100644 --- a/util/mmap-alloc.c +++ b/util/mmap-alloc.c @@ -118,9 +118,12 @@ static void *mmap_reserve(size_t size, int fd) * Activate memory in a reserved region from the given fd (if any), to make * it accessible. */ -static void *mmap_activate(void *ptr, size_t size, int fd, bool readonly, - bool shared, bool is_pmem, off_t map_offset) +static void *mmap_activate(void *ptr, size_t size, int fd, + uint32_t qemu_map_flags, off_t map_offset) { + const bool readonly =3D qemu_map_flags & QEMU_MAP_READONLY; + const bool shared =3D qemu_map_flags & QEMU_MAP_SHARED; + const bool sync =3D qemu_map_flags & QEMU_MAP_SYNC; const int prot =3D PROT_READ | (readonly ? 0 : PROT_WRITE); int map_sync_flags =3D 0; int flags =3D MAP_FIXED; @@ -128,7 +131,7 @@ static void *mmap_activate(void *ptr, size_t size, int = fd, bool readonly, =20 flags |=3D fd =3D=3D -1 ? MAP_ANONYMOUS : 0; flags |=3D shared ? MAP_SHARED : MAP_PRIVATE; - if (shared && is_pmem) { + if (shared && sync) { map_sync_flags =3D MAP_SYNC | MAP_SHARED_VALIDATE; } =20 @@ -173,9 +176,7 @@ static inline size_t mmap_guard_pagesize(int fd) void *qemu_ram_mmap(int fd, size_t size, size_t align, - bool readonly, - bool shared, - bool is_pmem, + uint32_t qemu_map_flags, off_t map_offset) { const size_t guard_pagesize =3D mmap_guard_pagesize(fd); @@ -199,7 +200,7 @@ void *qemu_ram_mmap(int fd, =20 offset =3D QEMU_ALIGN_UP((uintptr_t)guardptr, align) - (uintptr_t)guar= dptr; =20 - ptr =3D mmap_activate(guardptr + offset, size, fd, readonly, shared, i= s_pmem, + ptr =3D mmap_activate(guardptr + offset, size, fd, qemu_map_flags, map_offset); if (ptr =3D=3D MAP_FAILED) { munmap(guardptr, total); diff --git a/util/oslib-posix.c b/util/oslib-posix.c index 36820fec16..c12108c6cb 100644 --- a/util/oslib-posix.c +++ b/util/oslib-posix.c @@ -229,8 +229,9 @@ void *qemu_memalign(size_t alignment, size_t size) /* alloc shared memory pages */ void *qemu_anon_ram_alloc(size_t size, uint64_t *alignment, bool shared) { + const uint32_t qemu_map_flags =3D shared ? QEMU_MAP_SHARED : 0; size_t align =3D QEMU_VMALLOC_ALIGN; - void *ptr =3D qemu_ram_mmap(-1, size, align, false, shared, false, 0); + void *ptr =3D qemu_ram_mmap(-1, size, align, qemu_map_flags, 0); =20 if (ptr =3D=3D MAP_FAILED) { return NULL; --=20 2.30.2