mirror of https://gitlab.com/qemu-project/qemu
qga: implement qmp_guest_get_memory_blocks() for Linux with sysfs
We can get guest's memory block information by using command "guest-get-memory-blocks", the returned value contains a list of memory block info, such as phys-index, online state, can-offline info. Signed-off-by: zhanghailiang <zhang.zhanghailiang@huawei.com> *replaced guest-triggerable assertion with an error msg Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>
This commit is contained in:
zhanghailiang
Michael Roth
parent
a065aaa920
commit
bd240fca42
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@ -1992,9 +1992,240 @@ out:
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}
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}
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static void ga_read_sysfs_file(int dirfd, const char *pathname, char *buf,
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int size, Error **errp)
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{
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int fd;
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int res;
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errno = 0;
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fd = openat(dirfd, pathname, O_RDONLY);
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if (fd == -1) {
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error_setg_errno(errp, errno, "open sysfs file \"%s\"", pathname);
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return;
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}
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res = pread(fd, buf, size, 0);
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if (res == -1) {
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error_setg_errno(errp, errno, "pread sysfs file \"%s\"", pathname);
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} else if (res == 0) {
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error_setg(errp, "pread sysfs file \"%s\": unexpected EOF", pathname);
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}
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close(fd);
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}
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static void ga_write_sysfs_file(int dirfd, const char *pathname,
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const char *buf, int size, Error **errp)
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{
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int fd;
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errno = 0;
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fd = openat(dirfd, pathname, O_WRONLY);
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if (fd == -1) {
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error_setg_errno(errp, errno, "open sysfs file \"%s\"", pathname);
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return;
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}
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if (pwrite(fd, buf, size, 0) == -1) {
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error_setg_errno(errp, errno, "pwrite sysfs file \"%s\"", pathname);
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}
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close(fd);
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}
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/* Transfer online/offline status between @mem_blk and the guest system.
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*
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* On input either @errp or *@errp must be NULL.
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*
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* In system-to-@mem_blk direction, the following @mem_blk fields are accessed:
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* - R: mem_blk->phys_index
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* - W: mem_blk->online
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* - W: mem_blk->can_offline
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*
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* In @mem_blk-to-system direction, the following @mem_blk fields are accessed:
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* - R: mem_blk->phys_index
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* - R: mem_blk->online
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*- R: mem_blk->can_offline
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* Written members remain unmodified on error.
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*/
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static void transfer_memory_block(GuestMemoryBlock *mem_blk, bool sys2memblk,
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GuestMemoryBlockResponse *result,
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Error **errp)
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{
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char *dirpath;
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int dirfd;
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char *status;
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Error *local_err = NULL;
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if (!sys2memblk) {
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DIR *dp;
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if (!result) {
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error_setg(errp, "Internal error, 'result' should not be NULL");
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return;
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}
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errno = 0;
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dp = opendir("/sys/devices/system/memory/");
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/* if there is no 'memory' directory in sysfs,
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* we think this VM does not support online/offline memory block,
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* any other solution?
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*/
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if (!dp && errno == ENOENT) {
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result->response =
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GUEST_MEMORY_BLOCK_RESPONSE_TYPE_OPERATION_NOT_SUPPORTED;
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goto out1;
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}
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closedir(dp);
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}
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dirpath = g_strdup_printf("/sys/devices/system/memory/memory%" PRId64 "/",
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mem_blk->phys_index);
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dirfd = open(dirpath, O_RDONLY | O_DIRECTORY);
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if (dirfd == -1) {
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if (sys2memblk) {
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error_setg_errno(errp, errno, "open(\"%s\")", dirpath);
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} else {
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if (errno == ENOENT) {
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result->response = GUEST_MEMORY_BLOCK_RESPONSE_TYPE_NOT_FOUND;
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} else {
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result->response =
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GUEST_MEMORY_BLOCK_RESPONSE_TYPE_OPERATION_FAILED;
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}
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}
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g_free(dirpath);
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goto out1;
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}
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g_free(dirpath);
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status = g_malloc0(10);
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ga_read_sysfs_file(dirfd, "state", status, 10, &local_err);
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if (local_err) {
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/* treat with sysfs file that not exist in old kernel */
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if (errno == ENOENT) {
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error_free(local_err);
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if (sys2memblk) {
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mem_blk->online = true;
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mem_blk->can_offline = false;
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} else if (!mem_blk->online) {
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result->response =
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GUEST_MEMORY_BLOCK_RESPONSE_TYPE_OPERATION_NOT_SUPPORTED;
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}
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} else {
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if (sys2memblk) {
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error_propagate(errp, local_err);
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} else {
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result->response =
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GUEST_MEMORY_BLOCK_RESPONSE_TYPE_OPERATION_FAILED;
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}
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}
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goto out2;
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}
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if (sys2memblk) {
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char removable = '0';
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mem_blk->online = (strncmp(status, "online", 6) == 0);
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ga_read_sysfs_file(dirfd, "removable", &removable, 1, &local_err);
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if (local_err) {
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/* if no 'removable' file, it does't support offline mem blk */
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if (errno == ENOENT) {
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error_free(local_err);
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mem_blk->can_offline = false;
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} else {
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error_propagate(errp, local_err);
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}
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} else {
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mem_blk->can_offline = (removable != '0');
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}
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} else {
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if (mem_blk->online != (strncmp(status, "online", 6) == 0)) {
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char *new_state = mem_blk->online ? g_strdup("online") :
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g_strdup("offline");
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ga_write_sysfs_file(dirfd, "state", new_state, strlen(new_state),
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&local_err);
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g_free(new_state);
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if (local_err) {
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error_free(local_err);
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result->response =
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GUEST_MEMORY_BLOCK_RESPONSE_TYPE_OPERATION_FAILED;
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goto out2;
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}
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result->response = GUEST_MEMORY_BLOCK_RESPONSE_TYPE_SUCCESS;
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result->has_error_code = false;
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} /* otherwise pretend successful re-(on|off)-lining */
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}
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g_free(status);
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close(dirfd);
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return;
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out2:
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g_free(status);
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close(dirfd);
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out1:
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if (!sys2memblk) {
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result->has_error_code = true;
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result->error_code = errno;
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}
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}
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GuestMemoryBlockList *qmp_guest_get_memory_blocks(Error **errp)
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{
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error_set(errp, QERR_UNSUPPORTED);
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GuestMemoryBlockList *head, **link;
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Error *local_err = NULL;
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struct dirent *de;
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DIR *dp;
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head = NULL;
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link = &head;
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dp = opendir("/sys/devices/system/memory/");
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if (!dp) {
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error_setg_errno(errp, errno, "Can't open directory"
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"\"/sys/devices/system/memory/\"\n");
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return NULL;
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}
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/* Note: the phys_index of memory block may be discontinuous,
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* this is because a memblk is the unit of the Sparse Memory design, which
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* allows discontinuous memory ranges (ex. NUMA), so here we should
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* traverse the memory block directory.
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*/
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while ((de = readdir(dp)) != NULL) {
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GuestMemoryBlock *mem_blk;
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GuestMemoryBlockList *entry;
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if ((strncmp(de->d_name, "memory", 6) != 0) ||
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!(de->d_type & DT_DIR)) {
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continue;
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}
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mem_blk = g_malloc0(sizeof *mem_blk);
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/* The d_name is "memoryXXX", phys_index is block id, same as XXX */
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mem_blk->phys_index = strtoul(&de->d_name[6], NULL, 10);
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mem_blk->has_can_offline = true; /* lolspeak ftw */
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transfer_memory_block(mem_blk, true, NULL, &local_err);
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entry = g_malloc0(sizeof *entry);
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entry->value = mem_blk;
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*link = entry;
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link = &entry->next;
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}
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closedir(dp);
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if (local_err == NULL) {
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/* there's no guest with zero memory blocks */
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if (head == NULL) {
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error_setg(errp, "guest reported zero memory blocks!");
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}
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return head;
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}
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qapi_free_GuestMemoryBlockList(head);
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error_propagate(errp, local_err);
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return NULL;
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}
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