diff options
| -rw-r--r-- | backends/hostmem-file.c | 29 | ||||
| -rw-r--r-- | qemu-options.hx | 8 |
2 files changed, 36 insertions, 1 deletions
diff --git a/backends/hostmem-file.c b/backends/hostmem-file.c index fc4ef46d11..e44c319915 100644 --- a/backends/hostmem-file.c +++ b/backends/hostmem-file.c @@ -32,6 +32,7 @@ struct HostMemoryBackendFile { HostMemoryBackend parent_obj; bool share; + bool discard_data; char *mem_path; }; @@ -103,16 +104,44 @@ static void file_memory_backend_set_share(Object *o, bool value, Error **errp) fb->share = value; } +static bool file_memory_backend_get_discard_data(Object *o, Error **errp) +{ + return MEMORY_BACKEND_FILE(o)->discard_data; +} + +static void file_memory_backend_set_discard_data(Object *o, bool value, + Error **errp) +{ + MEMORY_BACKEND_FILE(o)->discard_data = value; +} + +static void file_backend_unparent(Object *obj) +{ + HostMemoryBackend *backend = MEMORY_BACKEND(obj); + HostMemoryBackendFile *fb = MEMORY_BACKEND_FILE(obj); + + if (host_memory_backend_mr_inited(backend) && fb->discard_data) { + void *ptr = memory_region_get_ram_ptr(&backend->mr); + uint64_t sz = memory_region_size(&backend->mr); + + qemu_madvise(ptr, sz, QEMU_MADV_REMOVE); + } +} + static void file_backend_class_init(ObjectClass *oc, void *data) { HostMemoryBackendClass *bc = MEMORY_BACKEND_CLASS(oc); bc->alloc = file_backend_memory_alloc; + oc->unparent = file_backend_unparent; object_class_property_add_bool(oc, "share", file_memory_backend_get_share, file_memory_backend_set_share, &error_abort); + object_class_property_add_bool(oc, "discard-data", + file_memory_backend_get_discard_data, file_memory_backend_set_discard_data, + &error_abort); object_class_property_add_str(oc, "mem-path", get_mem_path, set_mem_path, &error_abort); diff --git a/qemu-options.hx b/qemu-options.hx index 600614f6e5..77859a248c 100644 --- a/qemu-options.hx +++ b/qemu-options.hx @@ -4182,7 +4182,7 @@ property must be set. These objects are placed in the @table @option -@item -object memory-backend-file,id=@var{id},size=@var{size},mem-path=@var{dir},share=@var{on|off} +@item -object memory-backend-file,id=@var{id},size=@var{size},mem-path=@var{dir},share=@var{on|off},discard-data=@var{on|off} Creates a memory file backend object, which can be used to back the guest RAM with huge pages. The @option{id} parameter is a @@ -4194,6 +4194,12 @@ the path to either a shared memory or huge page filesystem mount. The @option{share} boolean option determines whether the memory region is marked as private to QEMU, or shared. The latter allows a co-operating external process to access the QEMU memory region. +Setting the @option{discard-data} boolean option to @var{on} +indicates that file contents can be destroyed when QEMU exits, +to avoid unnecessarily flushing data to the backing file. Note +that @option{discard-data} is only an optimization, and QEMU +might not discard file contents if it aborts unexpectedly or is +terminated using SIGKILL. @item -object rng-random,id=@var{id},filename=@var{/dev/random} |