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hostmem-file: reject invalid pmem file sizes

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Guests started with NVDIMMs larger than the underlying host file produce
confusing errors inside the guest.  This happens because the guest
accesses pages beyond the end of the file.

Check the pmem file size on startup and print a clear error message if
the size is invalid.

Fixes: https://bugzilla.redhat.com/show_bug.cgi?id=1669053
Cc: Wei Yang <richardw.yang@linux.intel.com>
Cc: Zhang Yi <yi.z.zhang@linux.intel.com>
Cc: Eduardo Habkost <ehabkost@redhat.com>
Cc: Igor Mammedov <imammedo@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-Id: <20190214031004.32522-3-stefanha@redhat.com>
Reviewed-by: Wei Yang <richardw.yang@linux.intel.com>
Reviewed-by: Igor Mammedov <imammedo@redhat.com>
Reviewed-by: Pankaj Gupta <pagupta@redhat.com>
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
This commit is contained in:
Stefan Hajnoczi 2019-02-14 11:10:04 +08:00 • committed by Eduardo Habkost
parent 336cfef495
commit 314aec4a6e
4 changed files with 94 additions and 0 deletions
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53
util/oslib-posix.c
View file

@ -500,6 +500,59 @@ void os_mem_prealloc(int fd, char *area, size_t memory, int smp_cpus,
}
}
uint64_t qemu_get_pmem_size(const char *filename, Error **errp)
{
struct stat st;
if (stat(filename, &st) < 0) {
error_setg(errp, "unable to stat pmem file \"%s\"", filename);
return 0;
}
#if defined(__linux__)
/* Special handling for devdax character devices */
if (S_ISCHR(st.st_mode)) {
char *subsystem_path = NULL;
char *subsystem = NULL;
char *size_path = NULL;
char *size_str = NULL;
uint64_t ret = 0;
subsystem_path = g_strdup_printf("/sys/dev/char/%d:%d/subsystem",
major(st.st_rdev), minor(st.st_rdev));
subsystem = g_file_read_link(subsystem_path, NULL);
if (!subsystem) {
error_setg(errp, "unable to read subsystem for pmem file \"%s\"",
filename);
goto devdax_err;
}
if (!g_str_has_suffix(subsystem, "/dax")) {
error_setg(errp, "pmem file \"%s\" is not a dax device", filename);
goto devdax_err;
}
size_path = g_strdup_printf("/sys/dev/char/%d:%d/size",
major(st.st_rdev), minor(st.st_rdev));
if (!g_file_get_contents(size_path, &size_str, NULL, NULL)) {
error_setg(errp, "unable to read size for pmem file \"%s\"",
size_path);
goto devdax_err;
}
ret = g_ascii_strtoull(size_str, NULL, 0);
devdax_err:
g_free(size_str);
g_free(size_path);
g_free(subsystem);
g_free(subsystem_path);
return ret;
}
#endif /* defined(__linux__) */
return st.st_size;
}
char *qemu_get_pid_name(pid_t pid)
{