qga: implement qmp_guest_get_vcpus() for Linux with sysfs
Signed-off-by: Laszlo Ersek <lersek@redhat.com> Reviewed-by: Eric Blake <eblake@redhat.com> Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>
This commit is contained in:
Laszlo Ersek
Michael Roth
parent
70e133a708
commit
d2baff6253
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@ -15,6 +15,10 @@
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#include <sys/types.h>
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#include <sys/ioctl.h>
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#include <sys/wait.h>
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#include <unistd.h>
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#include <errno.h>
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#include <fcntl.h>
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#include <inttypes.h>
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#include "qga/guest-agent-core.h"
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#include "qga-qmp-commands.h"
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#include "qapi/qmp/qerror.h"
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@ -1111,6 +1115,136 @@ error:
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return NULL;
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}
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#define SYSCONF_EXACT(name, err) sysconf_exact((name), #name, (err))
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static long sysconf_exact(int name, const char *name_str, Error **err)
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{
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long ret;
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errno = 0;
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ret = sysconf(name);
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if (ret == -1) {
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if (errno == 0) {
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error_setg(err, "sysconf(%s): value indefinite", name_str);
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} else {
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error_setg_errno(err, errno, "sysconf(%s)", name_str);
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}
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}
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return ret;
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}
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/* Transfer online/offline status between @vcpu 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-@vcpu direction, the following @vcpu fields are accessed:
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* - R: vcpu->logical_id
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* - W: vcpu->online
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* - W: vcpu->can_offline
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*
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* In @vcpu-to-system direction, the following @vcpu fields are accessed:
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* - R: vcpu->logical_id
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* - R: vcpu->online
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*
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* Written members remain unmodified on error.
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*/
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static void transfer_vcpu(GuestLogicalProcessor *vcpu, bool sys2vcpu,
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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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dirpath = g_strdup_printf("/sys/devices/system/cpu/cpu%" PRId64 "/",
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vcpu->logical_id);
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dirfd = open(dirpath, O_RDONLY | O_DIRECTORY);
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if (dirfd == -1) {
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error_setg_errno(errp, errno, "open(\"%s\")", dirpath);
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} else {
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static const char fn[] = "online";
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int fd;
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int res;
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fd = openat(dirfd, fn, sys2vcpu ? O_RDONLY : O_RDWR);
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if (fd == -1) {
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if (errno != ENOENT) {
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error_setg_errno(errp, errno, "open(\"%s/%s\")", dirpath, fn);
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} else if (sys2vcpu) {
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vcpu->online = true;
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vcpu->can_offline = false;
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} else if (!vcpu->online) {
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error_setg(errp, "logical processor #%" PRId64 " can't be "
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"offlined", vcpu->logical_id);
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} /* otherwise pretend successful re-onlining */
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} else {
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unsigned char status;
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res = pread(fd, &status, 1, 0);
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if (res == -1) {
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error_setg_errno(errp, errno, "pread(\"%s/%s\")", dirpath, fn);
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} else if (res == 0) {
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error_setg(errp, "pread(\"%s/%s\"): unexpected EOF", dirpath,
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fn);
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} else if (sys2vcpu) {
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vcpu->online = (status != '0');
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vcpu->can_offline = true;
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} else if (vcpu->online != (status != '0')) {
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status = '0' + vcpu->online;
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if (pwrite(fd, &status, 1, 0) == -1) {
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error_setg_errno(errp, errno, "pwrite(\"%s/%s\")", dirpath,
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fn);
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}
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} /* otherwise pretend successful re-(on|off)-lining */
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res = close(fd);
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g_assert(res == 0);
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}
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res = close(dirfd);
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g_assert(res == 0);
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}
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g_free(dirpath);
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}
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GuestLogicalProcessorList *qmp_guest_get_vcpus(Error **errp)
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{
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int64_t current;
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GuestLogicalProcessorList *head, **link;
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long sc_max;
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Error *local_err = NULL;
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current = 0;
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head = NULL;
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link = &head;
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sc_max = SYSCONF_EXACT(_SC_NPROCESSORS_CONF, &local_err);
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while (local_err == NULL && current < sc_max) {
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GuestLogicalProcessor *vcpu;
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GuestLogicalProcessorList *entry;
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vcpu = g_malloc0(sizeof *vcpu);
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vcpu->logical_id = current++;
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vcpu->has_can_offline = true; /* lolspeak ftw */
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transfer_vcpu(vcpu, true, &local_err);
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entry = g_malloc0(sizeof *entry);
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entry->value = vcpu;
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*link = entry;
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link = &entry->next;
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}
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if (local_err == NULL) {
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/* there's no guest with zero VCPUs */
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g_assert(head != NULL);
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return head;
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}
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qapi_free_GuestLogicalProcessorList(head);
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error_propagate(errp, local_err);
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return NULL;
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}
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#else /* defined(__linux__) */
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void qmp_guest_suspend_disk(Error **err)
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@ -1134,6 +1268,12 @@ GuestNetworkInterfaceList *qmp_guest_network_get_interfaces(Error **errp)
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return NULL;
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}
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GuestLogicalProcessorList *qmp_guest_get_vcpus(Error **errp)
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{
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error_set(errp, QERR_UNSUPPORTED);
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return NULL;
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}
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#endif
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#if !defined(CONFIG_FSFREEZE)
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@ -1167,12 +1307,6 @@ void qmp_guest_fstrim(bool has_minimum, int64_t minimum, Error **err)
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}
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#endif
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GuestLogicalProcessorList *qmp_guest_get_vcpus(Error **errp)
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{
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error_set(errp, QERR_UNSUPPORTED);
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return NULL;
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}
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int64_t qmp_guest_set_vcpus(GuestLogicalProcessorList *vcpus, Error **errp)
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{
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error_set(errp, QERR_UNSUPPORTED);
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