motorhead/qemu
1
0
Fork 0
mirror of https://github.com/Motorhead1991/qemu.git synced 2025-08-04 00:03:54 -06:00
Code Issues Projects Releases Packages Wiki Activity Actions

memory: fetch pmem size in get_file_size()

Browse source 
Neither stat(2) nor lseek(2) report the size of Linux devdax pmem
character device nodes.  Commit 314aec4a6e
("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 <stefanha@redhat.com>
Message-Id: <20190830093056.12572-1-stefanha@redhat.com>
Reviewed-by: Eduardo Habkost <ehabkost@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Stefan Hajnoczi 2019-08-30 10:30:56 +01:00 • committed by Paolo Bonzini
parent 41a2635124
commit 72d41eb4b8
5 changed files with 33 additions and 96 deletions
Download patch file Download diff file Expand all files Collapse all files

22
backends/hostmem-file.c
View file

@ -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),