mirror of https://github.com/proxmox/mirror_qemu
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 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>
master
parent
41a2635124
commit
72d41eb4b8
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@ -58,28 +58,6 @@ file_backend_memory_alloc(HostMemoryBackend *backend, Error **errp)
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return;
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return;
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}
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}
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/*
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* Verify pmem file size since starting a guest with an incorrect size
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* leads to confusing failures inside the guest.
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*/
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if (fb->is_pmem) {
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Error *local_err = NULL;
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uint64_t size;
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size = qemu_get_pmem_size(fb->mem_path, &local_err);
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if (local_err) {
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error_propagate(errp, local_err);
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return;
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}
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if (size && backend->size > size) {
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error_setg(errp, "size property %" PRIu64 " is larger than "
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"pmem file \"%s\" size %" PRIu64, backend->size,
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fb->mem_path, size);
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return;
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}
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}
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backend->force_prealloc = mem_prealloc;
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backend->force_prealloc = mem_prealloc;
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name = host_memory_backend_get_name(backend);
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name = host_memory_backend_get_name(backend);
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memory_region_init_ram_from_file(&backend->mr, OBJECT(backend),
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memory_region_init_ram_from_file(&backend->mr, OBJECT(backend),
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34
exec.c
34
exec.c
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@ -1791,7 +1791,39 @@ long qemu_maxrampagesize(void)
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#ifdef CONFIG_POSIX
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#ifdef CONFIG_POSIX
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static int64_t get_file_size(int fd)
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static int64_t get_file_size(int fd)
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{
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{
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int64_t size = lseek(fd, 0, SEEK_END);
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int64_t size;
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#if defined(__linux__)
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struct stat st;
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if (fstat(fd, &st) < 0) {
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return -errno;
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}
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/* Special handling for devdax character devices */
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if (S_ISCHR(st.st_mode)) {
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g_autofree char *subsystem_path = NULL;
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g_autofree char *subsystem = NULL;
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subsystem_path = g_strdup_printf("/sys/dev/char/%d:%d/subsystem",
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major(st.st_rdev), minor(st.st_rdev));
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subsystem = g_file_read_link(subsystem_path, NULL);
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if (subsystem && g_str_has_suffix(subsystem, "/dax")) {
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g_autofree char *size_path = NULL;
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g_autofree char *size_str = NULL;
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size_path = g_strdup_printf("/sys/dev/char/%d:%d/size",
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major(st.st_rdev), minor(st.st_rdev));
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if (g_file_get_contents(size_path, &size_str, NULL, NULL)) {
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return g_ascii_strtoll(size_str, NULL, 0);
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}
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}
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}
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#endif /* defined(__linux__) */
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/* st.st_size may be zero for special files yet lseek(2) works */
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size = lseek(fd, 0, SEEK_END);
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if (size < 0) {
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if (size < 0) {
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return -errno;
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return -errno;
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}
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}
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@ -570,19 +570,6 @@ void qemu_set_tty_echo(int fd, bool echo);
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void os_mem_prealloc(int fd, char *area, size_t sz, int smp_cpus,
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void os_mem_prealloc(int fd, char *area, size_t sz, int smp_cpus,
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Error **errp);
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Error **errp);
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/**
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* qemu_get_pmem_size:
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* @filename: path to a pmem file
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* @errp: pointer to a NULL-initialized error object
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*
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* Determine the size of a persistent memory file. Besides supporting files on
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* DAX file systems, this function also supports Linux devdax character
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* devices.
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*
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* Returns: the size or 0 on failure
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*/
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uint64_t qemu_get_pmem_size(const char *filename, Error **errp);
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/**
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/**
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* qemu_get_pid_name:
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* qemu_get_pid_name:
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* @pid: pid of a process
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* @pid: pid of a process
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@ -514,60 +514,6 @@ void os_mem_prealloc(int fd, char *area, size_t memory, int smp_cpus,
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}
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}
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}
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}
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uint64_t qemu_get_pmem_size(const char *filename, Error **errp)
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{
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struct stat st;
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if (stat(filename, &st) < 0) {
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error_setg(errp, "unable to stat pmem file \"%s\"", filename);
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return 0;
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}
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#if defined(__linux__)
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/* Special handling for devdax character devices */
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if (S_ISCHR(st.st_mode)) {
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char *subsystem_path = NULL;
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char *subsystem = NULL;
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char *size_path = NULL;
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char *size_str = NULL;
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uint64_t ret = 0;
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subsystem_path = g_strdup_printf("/sys/dev/char/%d:%d/subsystem",
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major(st.st_rdev), minor(st.st_rdev));
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subsystem = g_file_read_link(subsystem_path, NULL);
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if (!subsystem) {
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error_setg(errp, "unable to read subsystem for pmem file \"%s\"",
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filename);
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goto devdax_err;
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}
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if (!g_str_has_suffix(subsystem, "/dax")) {
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error_setg(errp, "pmem file \"%s\" is not a dax device", filename);
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goto devdax_err;
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}
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size_path = g_strdup_printf("/sys/dev/char/%d:%d/size",
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major(st.st_rdev), minor(st.st_rdev));
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if (!g_file_get_contents(size_path, &size_str, NULL, NULL)) {
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error_setg(errp, "unable to read size for pmem file \"%s\"",
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size_path);
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goto devdax_err;
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}
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ret = g_ascii_strtoull(size_str, NULL, 0);
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devdax_err:
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g_free(size_str);
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g_free(size_path);
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g_free(subsystem);
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g_free(subsystem_path);
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return ret;
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}
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#endif /* defined(__linux__) */
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return st.st_size;
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}
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char *qemu_get_pid_name(pid_t pid)
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char *qemu_get_pid_name(pid_t pid)
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{
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{
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char *name = NULL;
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char *name = NULL;
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@ -562,12 +562,6 @@ void os_mem_prealloc(int fd, char *area, size_t memory, int smp_cpus,
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}
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}
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}
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}
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uint64_t qemu_get_pmem_size(const char *filename, Error **errp)
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{
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error_setg(errp, "pmem support not available");
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return 0;
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}
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char *qemu_get_pid_name(pid_t pid)
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char *qemu_get_pid_name(pid_t pid)
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{
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{
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/* XXX Implement me */
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/* XXX Implement me */
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Loading…
Reference in New Issue