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bh=pW9aucHl9ELVmz+74I/jqd2gfJxUAeqYfg06JqdTZIw=; b=AeqSGEwULD+L/wNHCejE8ggVIP7nuURBTah78LRUrS99ixsKFSd9fZ+F9VItdYvma/vlch Nb1rfj1Z1GCKar4FiJl0ZX14arGrG/tue0BkM78P/9TcBZ2ZwkGh2CJH0NN9L7h6zHnxc2 0rVGcnOk9aMVElcrEdIomUYT0KT/moU= X-MC-Unique: Ixw2C_iTNf29gVvXYFNoEw-1 From: David Hildenbrand To: qemu-devel@nongnu.org Subject: [PATCH v5 03/14] util/mmap-alloc: Factor out activating of memory to mmap_activate() Date: Tue, 13 Apr 2021 11:14:10 +0200 Message-Id: <20210413091421.7707-4-david@redhat.com> In-Reply-To: <20210413091421.7707-1-david@redhat.com> References: <20210413091421.7707-1-david@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=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" We want to activate memory within a reserved memory region, to make it accessible. Let's factor that out. Reviewed-by: Richard Henderson Acked-by: Murilo Opsfelder Araujo Reviewed-by: Peter Xu Signed-off-by: David Hildenbrand --- util/mmap-alloc.c | 94 +++++++++++++++++++++++++---------------------- 1 file changed, 50 insertions(+), 44 deletions(-) diff --git a/util/mmap-alloc.c b/util/mmap-alloc.c index 223d66219c..0e2bd7bc0e 100644 --- a/util/mmap-alloc.c +++ b/util/mmap-alloc.c @@ -114,6 +114,52 @@ static void *mmap_reserve(size_t size, int fd) return mmap(0, size, PROT_NONE, flags, fd, 0); } =20 +/* + * 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) +{ + const int prot =3D PROT_READ | (readonly ? 0 : PROT_WRITE); + int map_sync_flags =3D 0; + int flags =3D MAP_FIXED; + void *activated_ptr; + + flags |=3D fd =3D=3D -1 ? MAP_ANONYMOUS : 0; + flags |=3D shared ? MAP_SHARED : MAP_PRIVATE; + if (shared && is_pmem) { + map_sync_flags =3D MAP_SYNC | MAP_SHARED_VALIDATE; + } + + activated_ptr =3D mmap(ptr, size, prot, flags | map_sync_flags, fd, + map_offset); + if (activated_ptr =3D=3D MAP_FAILED && map_sync_flags) { + if (errno =3D=3D ENOTSUP) { + char *proc_link =3D g_strdup_printf("/proc/self/fd/%d", fd); + char *file_name =3D g_malloc0(PATH_MAX); + int len =3D readlink(proc_link, file_name, PATH_MAX - 1); + + if (len < 0) { + len =3D 0; + } + file_name[len] =3D '\0'; + fprintf(stderr, "Warning: requesting persistence across crashe= s " + "for backend file %s failed. Proceeding without " + "persistence, data might become corrupted in case of h= ost " + "crash.\n", file_name); + g_free(proc_link); + g_free(file_name); + } + /* + * If mmap failed with MAP_SHARED_VALIDATE | MAP_SYNC, we will try + * again without these flags to handle backwards compatibility. + */ + activated_ptr =3D mmap(ptr, size, prot, flags, fd, map_offset); + } + return activated_ptr; +} + static inline size_t mmap_guard_pagesize(int fd) { #if defined(__powerpc64__) && defined(__linux__) @@ -133,13 +179,8 @@ void *qemu_ram_mmap(int fd, off_t map_offset) { const size_t guard_pagesize =3D mmap_guard_pagesize(fd); - int prot; - int flags; - int map_sync_flags =3D 0; - size_t offset; - size_t total; - void *guardptr; - void *ptr; + size_t offset, total; + void *ptr, *guardptr; =20 /* * Note: this always allocates at least one extra page of virtual addr= ess @@ -156,45 +197,10 @@ void *qemu_ram_mmap(int fd, /* Always align to host page size */ assert(align >=3D guard_pagesize); =20 - flags =3D MAP_FIXED; - flags |=3D fd =3D=3D -1 ? MAP_ANONYMOUS : 0; - flags |=3D shared ? MAP_SHARED : MAP_PRIVATE; - if (shared && is_pmem) { - map_sync_flags =3D MAP_SYNC | MAP_SHARED_VALIDATE; - } - offset =3D QEMU_ALIGN_UP((uintptr_t)guardptr, align) - (uintptr_t)guar= dptr; =20 - prot =3D PROT_READ | (readonly ? 0 : PROT_WRITE); - - ptr =3D mmap(guardptr + offset, size, prot, - flags | map_sync_flags, fd, map_offset); - - if (ptr =3D=3D MAP_FAILED && map_sync_flags) { - if (errno =3D=3D ENOTSUP) { - char *proc_link, *file_name; - int len; - proc_link =3D g_strdup_printf("/proc/self/fd/%d", fd); - file_name =3D g_malloc0(PATH_MAX); - len =3D readlink(proc_link, file_name, PATH_MAX - 1); - if (len < 0) { - len =3D 0; - } - file_name[len] =3D '\0'; - fprintf(stderr, "Warning: requesting persistence across crashe= s " - "for backend file %s failed. Proceeding without " - "persistence, data might become corrupted in case of h= ost " - "crash.\n", file_name); - g_free(proc_link); - g_free(file_name); - } - /* - * if map failed with MAP_SHARED_VALIDATE | MAP_SYNC, - * we will remove these flags to handle compatibility. - */ - ptr =3D mmap(guardptr + offset, size, prot, flags, fd, map_offset); - } - + ptr =3D mmap_activate(guardptr + offset, size, fd, readonly, shared, i= s_pmem, + map_offset); if (ptr =3D=3D MAP_FAILED) { munmap(guardptr, total); return MAP_FAILED; --=20 2.30.2