Introduce memory_region_init_rom_device_from_file() which mmap the backing file of ROM devices. This allows to reduce QEMU memory footprint as the same file can be shared between multiple instances of QEMU.
Signed-off-by: Philippe Mathieu-Daudé <phi...@redhat.com> --- include/exec/memory.h | 85 +++++++++++++++++++++++++++++++++++++ softmmu/memory.c | 98 +++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 183 insertions(+) diff --git a/include/exec/memory.h b/include/exec/memory.h index c6fb714e499..bacf7495003 100644 --- a/include/exec/memory.h +++ b/include/exec/memory.h @@ -487,6 +487,9 @@ struct MemoryRegion { const char *name; unsigned ioeventfd_nb; MemoryRegionIoeventfd *ioeventfds; +#ifndef CONFIG_POSIX + gchar *contents; +#endif }; struct IOMMUMemoryRegion { @@ -1131,6 +1134,43 @@ void memory_region_init_rom_device_nomigrate(MemoryRegion *mr, uint64_t size, Error **errp); +/** + * memory_region_init_rom_device_from_file_nomigrate: + * Initialize a ROM memory region from the specified backing file. + * Writes are handled via callbacks. + * + * Note that this function does not do anything to cause the data in the + * RAM side of the memory region to be migrated; that is the responsibility + * of the caller. + * + * @mr: the #MemoryRegion to be initialized. + * @owner: the object that tracks the region's reference count + * @ops: callbacks for write access handling (must not be NULL). + * @opaque: passed to the read and write callbacks of the @ops structure. + * @name: Region name, becomes part of RAMBlock name used in migration stream + * must be unique within any device + * @size: size of the region. + * @ram_flags: specify the properties of the ram block, which can be one + * or bit-or of following values + * - RAM_SHARED: mmap the backing file or device with MAP_SHARED + * - RAM_PMEM: the backend @mem_path is persistent memory + * Other bits are ignored. + * @path: specify the backing file + * @readonly: true to open @path for reading, false for read/write. + * @errp: pointer to Error*, to store an error if it happens. + */ +void memory_region_init_rom_device_from_file_nomigrate(MemoryRegion *mr, + Object *owner, + const MemoryRegionOps *ops, + void *opaque, + const char *name, + uint64_t size, + uint64_t align, + uint32_t ram_flags, + const char *path, + bool readonly, + Error **errp); + /** * memory_region_init_iommu: Initialize a memory region of a custom type * that translates addresses @@ -1249,6 +1289,51 @@ void memory_region_init_rom_device(MemoryRegion *mr, Error **errp); +/** + * memory_region_init_rom_device_from_file: + * Initialize a ROM memory region from the specified backing file. + * Writes are handled via callbacks. + * + * This function initializes a memory region backed by RAM for reads + * and callbacks for writes, and arranges for the RAM backing to + * be migrated (by calling vmstate_register_ram() + * if @owner is a DeviceState, or vmstate_register_ram_global() if + * @owner is NULL). + * + * TODO: Currently we restrict @owner to being either NULL (for + * global RAM regions with no owner) or devices, so that we can + * give the RAM block a unique name for migration purposes. + * We should lift this restriction and allow arbitrary Objects. + * If you pass a non-NULL non-device @owner then we will assert. + * + * @mr: the #MemoryRegion to be initialized. + * @owner: the object that tracks the region's reference count + * @ops: callbacks for write access handling (must not be NULL). + * @opaque: passed to the read and write callbacks of the @ops structure. + * @name: Region name, becomes part of RAMBlock name used in migration stream + * must be unique within any device + * @size: size of the region. + * @ram_flags: specify the properties of the ram block, which can be one + * or bit-or of following values + * - RAM_SHARED: mmap the backing file or device with MAP_SHARED + * - RAM_PMEM: the backend @mem_path is persistent memory + * Other bits are ignored. + * @path: specify the backing file + * @readonly: true to open @path for reading, false for read/write. + * @errp: pointer to Error*, to store an error if it happens. + */ +void memory_region_init_rom_device_from_file(MemoryRegion *mr, + Object *owner, + const MemoryRegionOps *ops, + void *opaque, + const char *name, + uint64_t size, + uint64_t align, + uint32_t ram_flags, + const char *path, + bool readonly, + Error **errp); + /** * memory_region_owner: get a memory region's owner. * diff --git a/softmmu/memory.c b/softmmu/memory.c index 874a8fccdee..ea1892a8cd6 100644 --- a/softmmu/memory.c +++ b/softmmu/memory.c @@ -1120,6 +1120,14 @@ static void memory_region_destructor_ram(MemoryRegion *mr) qemu_ram_free(mr->ram_block); } +#ifndef CONFIG_POSIX +static void memory_region_destructor_contents(MemoryRegion *mr) +{ + qemu_ram_free(mr->ram_block); + g_free(mr->contents); +} +#endif + static bool memory_region_need_escape(char c) { return c == '/' || c == '[' || c == '\\' || c == ']'; @@ -1712,6 +1720,96 @@ void memory_region_init_rom_device_nomigrate(MemoryRegion *mr, } } +void memory_region_init_rom_device_from_file_nomigrate(MemoryRegion *mr, + Object *owner, + const MemoryRegionOps *ops, + void *opaque, + const char *name, + uint64_t size, + uint64_t align, + uint32_t ram_flags, + const char *path, + bool readonly, + Error **errp) +{ + Error *err = NULL; + + assert(ops); +#ifdef CONFIG_POSIX + memory_region_init(mr, owner, name, size); + mr->opaque = opaque; + mr->ops = ops; + mr->rom_device = true; + mr->readonly = readonly; + mr->ram = true; + mr->align = align; + mr->terminates = true; + mr->destructor = memory_region_destructor_ram; + mr->ram_block = qemu_ram_alloc_from_file(size, mr, ram_flags, path, + readonly, &err); + if (err) { + mr->size = int128_zero(); + object_unparent(OBJECT(mr)); + error_propagate(errp, err); + } +#else + g_autoptr(GError) gerr = NULL; + gsize len; + + memory_region_init(mr, owner, name, size); + mr->ops = ops; + mr->opaque = opaque; + mr->terminates = true; + mr->rom_device = true; + + if (!g_file_get_contents(path, &mr->contents, &len, &gerr)) { + error_setg(errp, "Unable to read '%s': %s", path, gerr->message); + return; + } + mr->destructor = memory_region_destructor_contents; + mr->contents = g_realloc(mr->contents, size); + mr->ram_block = qemu_ram_alloc_from_ptr(size, mr->contents, mr, &err); + if (err) { + mr->size = int128_zero(); + object_unparent(OBJECT(mr)); + error_propagate(errp, err); + } +#endif +} + +void memory_region_init_rom_device_from_file(MemoryRegion *mr, + Object *owner, + const MemoryRegionOps *ops, + void *opaque, + const char *name, + uint64_t size, + uint64_t align, + uint32_t ram_flags, + const char *path, + bool readonly, + Error **errp) +{ + DeviceState *owner_dev; + Error *err = NULL; + + memory_region_init_rom_device_from_file_nomigrate(mr, owner, ops, opaque, + name, size, align, + ram_flags, path, readonly, + &err); + if (err) { + error_propagate(errp, err); + return; + } + /* This will assert if owner is neither NULL nor a DeviceState. + * We only want the owner here for the purposes of defining a + * unique name for migration. TODO: Ideally we should implement + * a naming scheme for Objects which are not DeviceStates, in + * which case we can relax this restriction. + */ + owner_dev = DEVICE(owner); + vmstate_register_ram(mr, owner_dev); +} + void memory_region_init_iommu(void *_iommu_mr, size_t instance_size, const char *mrtypename, -- 2.26.2