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Tue, 12 May 2020 08:48:57 +0000 (UTC) Date: Tue, 12 May 2020 09:48:55 +0100 From: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= To: elena.ufimtseva@oracle.com Subject: Re: [PATCH RESEND v6 01/36] memory: alloc RAM from file at offset Message-ID: <20200512084855.GC1191162@redhat.com> References: MIME-Version: 1.0 In-Reply-To: User-Agent: Mutt/1.13.4 (2020-02-15) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Received-SPF: pass client-ip=205.139.110.61; envelope-from=berrange@redhat.com; helo=us-smtp-delivery-1.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/05/12 02:02:05 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] X-Spam_score_int: -10 X-Spam_score: -1.1 X-Spam_bar: - X-Spam_report: (-1.1 / 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, FROM_EXCESS_BASE64=0.979, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H2=-0.001, SPF_PASS=-0.001, URIBL_BLOCKED=0.001 autolearn=_AUTOLEARN 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: , Reply-To: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= Cc: fam@euphon.net, john.g.johnson@oracle.com, swapnil.ingle@nutanix.com, mst@redhat.com, qemu-devel@nongnu.org, kraxel@redhat.com, jag.raman@oracle.com, quintela@redhat.com, armbru@redhat.com, kanth.ghatraju@oracle.com, felipe@nutanix.com, thuth@redhat.com, ehabkost@redhat.com, konrad.wilk@oracle.com, dgilbert@redhat.com, liran.alon@oracle.com, stefanha@redhat.com, thanos.makatos@nutanix.com, rth@twiddle.net, kwolf@redhat.com, mreitz@redhat.com, ross.lagerwall@citrix.com, marcandre.lureau@gmail.com, pbonzini@redhat.com Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Wed, Apr 22, 2020 at 09:13:36PM -0700, elena.ufimtseva@oracle.com wrote: > From: Jagannathan Raman > > Allow RAM MemoryRegion to be created from an offset in a file, instead > of allocating at offset of 0 by default. This is needed to synchronize > RAM between QEMU & remote process. Can you elaborate on why remote processes require the RAM to be offset from zero ? NB, I'm not objecting - I'm just curious to understand more. > > Signed-off-by: Jagannathan Raman > Signed-off-by: John G Johnson > Signed-off-by: Elena Ufimtseva > Reviewed-by: Dr. David Alan Gilbert > --- > exec.c | 11 +++++++---- > include/exec/ram_addr.h | 2 +- > include/qemu/mmap-alloc.h | 3 ++- > memory.c | 2 +- > util/mmap-alloc.c | 7 ++++--- > util/oslib-posix.c | 2 +- > 6 files changed, 16 insertions(+), 11 deletions(-) > > diff --git a/exec.c b/exec.c > index 2874bb5088..d0ac9545f4 100644 > --- a/exec.c > +++ b/exec.c > @@ -1801,6 +1801,7 @@ static void *file_ram_alloc(RAMBlock *block, > ram_addr_t memory, > int fd, > bool truncate, > + off_t offset, > Error **errp) > { > void *area; > @@ -1851,7 +1852,8 @@ static void *file_ram_alloc(RAMBlock *block, > } > > area = qemu_ram_mmap(fd, memory, block->mr->align, > - block->flags & RAM_SHARED, block->flags & RAM_PMEM); > + block->flags & RAM_SHARED, block->flags & RAM_PMEM, > + offset); > if (area == MAP_FAILED) { > error_setg_errno(errp, errno, > "unable to map backing store for guest RAM"); > @@ -2283,7 +2285,7 @@ static void ram_block_add(RAMBlock *new_block, Error **errp, bool shared) > #ifdef CONFIG_POSIX > RAMBlock *qemu_ram_alloc_from_fd(ram_addr_t size, MemoryRegion *mr, > uint32_t ram_flags, int fd, > - Error **errp) > + off_t offset, Error **errp) > { > RAMBlock *new_block; > Error *local_err = NULL; > @@ -2328,7 +2330,8 @@ RAMBlock *qemu_ram_alloc_from_fd(ram_addr_t size, MemoryRegion *mr, > new_block->used_length = size; > new_block->max_length = size; > new_block->flags = ram_flags; > - new_block->host = file_ram_alloc(new_block, size, fd, !file_size, errp); > + new_block->host = file_ram_alloc(new_block, size, fd, !file_size, offset, > + errp); > if (!new_block->host) { > g_free(new_block); > return NULL; > @@ -2358,7 +2361,7 @@ RAMBlock *qemu_ram_alloc_from_file(ram_addr_t size, MemoryRegion *mr, > return NULL; > } > > - block = qemu_ram_alloc_from_fd(size, mr, ram_flags, fd, errp); > + block = qemu_ram_alloc_from_fd(size, mr, ram_flags, fd, 0, errp); > if (!block) { > if (created) { > unlink(mem_path); > diff --git a/include/exec/ram_addr.h b/include/exec/ram_addr.h > index 5e59a3d8d7..1b9f489ff0 100644 > --- a/include/exec/ram_addr.h > +++ b/include/exec/ram_addr.h > @@ -121,7 +121,7 @@ RAMBlock *qemu_ram_alloc_from_file(ram_addr_t size, MemoryRegion *mr, > Error **errp); > RAMBlock *qemu_ram_alloc_from_fd(ram_addr_t size, MemoryRegion *mr, > uint32_t ram_flags, int fd, > - Error **errp); > + off_t offset, Error **errp); > > RAMBlock *qemu_ram_alloc_from_ptr(ram_addr_t size, void *host, > MemoryRegion *mr, Error **errp); > diff --git a/include/qemu/mmap-alloc.h b/include/qemu/mmap-alloc.h > index e786266b92..4f579858bc 100644 > --- a/include/qemu/mmap-alloc.h > +++ b/include/qemu/mmap-alloc.h > @@ -25,7 +25,8 @@ void *qemu_ram_mmap(int fd, > size_t size, > size_t align, > bool shared, > - bool is_pmem); > + bool is_pmem, > + off_t start); > > void qemu_ram_munmap(int fd, void *ptr, size_t size); > > diff --git a/memory.c b/memory.c > index 601b749906..f5fec476b7 100644 > --- a/memory.c > +++ b/memory.c > @@ -1596,7 +1596,7 @@ void memory_region_init_ram_from_fd(MemoryRegion *mr, > mr->destructor = memory_region_destructor_ram; > mr->ram_block = qemu_ram_alloc_from_fd(size, mr, > share ? RAM_SHARED : 0, > - fd, &err); > + fd, 0, &err); > mr->dirty_log_mask = tcg_enabled() ? (1 << DIRTY_MEMORY_CODE) : 0; > if (err) { > mr->size = int128_zero(); > diff --git a/util/mmap-alloc.c b/util/mmap-alloc.c > index 27dcccd8ec..a28f7025f0 100644 > --- a/util/mmap-alloc.c > +++ b/util/mmap-alloc.c > @@ -86,7 +86,8 @@ void *qemu_ram_mmap(int fd, > size_t size, > size_t align, > bool shared, > - bool is_pmem) > + bool is_pmem, > + off_t start) > { > int flags; > int map_sync_flags = 0; > @@ -147,7 +148,7 @@ void *qemu_ram_mmap(int fd, > offset = QEMU_ALIGN_UP((uintptr_t)guardptr, align) - (uintptr_t)guardptr; > > ptr = mmap(guardptr + offset, size, PROT_READ | PROT_WRITE, > - flags | map_sync_flags, fd, 0); > + flags | map_sync_flags, fd, start); > > if (ptr == MAP_FAILED && map_sync_flags) { > if (errno == ENOTSUP) { > @@ -172,7 +173,7 @@ void *qemu_ram_mmap(int fd, > * we will remove these flags to handle compatibility. > */ > ptr = mmap(guardptr + offset, size, PROT_READ | PROT_WRITE, > - flags, fd, 0); > + flags, fd, start); > } > > if (ptr == MAP_FAILED) { > diff --git a/util/oslib-posix.c b/util/oslib-posix.c > index 062236a1ab..4c6b9e90c6 100644 > --- a/util/oslib-posix.c > +++ b/util/oslib-posix.c > @@ -209,7 +209,7 @@ 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 = QEMU_VMALLOC_ALIGN; > - void *ptr = qemu_ram_mmap(-1, size, align, shared, false); > + void *ptr = qemu_ram_mmap(-1, size, align, shared, false, 0); > > if (ptr == MAP_FAILED) { > return NULL; > -- > 2.25.GIT > Regards, Daniel -- |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o- https://fstop138.berrange.com :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|