From 72d41eb4b8f923de91e8f06dc20aa86b0a9155fb Mon Sep 17 00:00:00 2001 From: Stefan Hajnoczi Date: Fri, 30 Aug 2019 10:30:56 +0100 Subject: memory: fetch pmem size in get_file_size() Neither stat(2) nor lseek(2) report the size of Linux devdax pmem character device nodes. Commit 314aec4a6e06844937f1677f6cba21981005f389 ("hostmem-file: reject invalid pmem file sizes") added code to hostmem-file.c to fetch the size from sysfs and compare against the user-provided size=NUM parameter: if (backend->size > size) { error_setg(errp, "size property %" PRIu64 " is larger than " "pmem file \"%s\" size %" PRIu64, backend->size, fb->mem_path, size); return; } It turns out that exec.c:qemu_ram_alloc_from_fd() already has an equivalent size check but it skips devdax pmem character devices because lseek(2) returns 0: if (file_size > 0 && file_size < size) { error_setg(errp, "backing store %s size 0x%" PRIx64 " does not match 'size' option 0x" RAM_ADDR_FMT, mem_path, file_size, size); return NULL; } This patch moves the devdax pmem file size code into get_file_size() so that we check the memory size in a single place: qemu_ram_alloc_from_fd(). This simplifies the code and makes it more general. This also fixes the problem that hostmem-file only checks the devdax pmem file size when the pmem=on parameter is given. An unchecked size=NUM parameter can lead to SIGBUS in QEMU so we must always fetch the file size for Linux devdax pmem character device nodes. Signed-off-by: Stefan Hajnoczi Message-Id: <20190830093056.12572-1-stefanha@redhat.com> Reviewed-by: Eduardo Habkost Signed-off-by: Paolo Bonzini --- backends/hostmem-file.c | 22 ---------------------- 1 file changed, 22 deletions(-) (limited to 'backends') diff --git a/backends/hostmem-file.c b/backends/hostmem-file.c index ecc15e3..be64020 100644 --- a/backends/hostmem-file.c +++ b/backends/hostmem-file.c @@ -58,28 +58,6 @@ file_backend_memory_alloc(HostMemoryBackend *backend, Error **errp) return; } - /* - * Verify pmem file size since starting a guest with an incorrect size - * leads to confusing failures inside the guest. - */ - if (fb->is_pmem) { - Error *local_err = NULL; - uint64_t size; - - size = qemu_get_pmem_size(fb->mem_path, &local_err); - if (local_err) { - error_propagate(errp, local_err); - return; - } - - if (size && backend->size > size) { - error_setg(errp, "size property %" PRIu64 " is larger than " - "pmem file \"%s\" size %" PRIu64, backend->size, - fb->mem_path, size); - return; - } - } - backend->force_prealloc = mem_prealloc; name = host_memory_backend_get_name(backend); memory_region_init_ram_from_file(&backend->mr, OBJECT(backend), -- cgit v1.1