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qga: implement qmp_guest_get_vcpus() for Linux with sysfs

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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 2013-03-06 22:59:30 +01:00 committed by Michael Roth
parent 70e133a708
commit d2baff6253
1 changed files with 140 additions and 6 deletions
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146
qga/commands-posix.c
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@ -15,6 +15,10 @@
#include <sys/types.h>
#include <sys/ioctl.h>
#include <sys/wait.h>
#include <unistd.h>
#include <errno.h>
#include <fcntl.h>
#include <inttypes.h>
#include "qga/guest-agent-core.h"
#include "qga-qmp-commands.h"
#include "qapi/qmp/qerror.h"
@ -1111,6 +1115,136 @@ error:
return NULL;
}
#define SYSCONF_EXACT(name, err) sysconf_exact((name), #name, (err))
static long sysconf_exact(int name, const char *name_str, Error **err)
{
long ret;
errno = 0;
ret = sysconf(name);
if (ret == -1) {
if (errno == 0) {
error_setg(err, "sysconf(%s): value indefinite", name_str);
} else {
error_setg_errno(err, errno, "sysconf(%s)", name_str);
}
}
return ret;
}
/* Transfer online/offline status between @vcpu and the guest system.
*
* On input either @errp or *@errp must be NULL.
*
* In system-to-@vcpu direction, the following @vcpu fields are accessed:
* - R: vcpu->logical_id
* - W: vcpu->online
* - W: vcpu->can_offline
*
* In @vcpu-to-system direction, the following @vcpu fields are accessed:
* - R: vcpu->logical_id
* - R: vcpu->online
*
* Written members remain unmodified on error.
*/
static void transfer_vcpu(GuestLogicalProcessor *vcpu, bool sys2vcpu,
Error **errp)
{
char *dirpath;
int dirfd;
dirpath = g_strdup_printf("/sys/devices/system/cpu/cpu%" PRId64 "/",
vcpu->logical_id);
dirfd = open(dirpath, O_RDONLY | O_DIRECTORY);
if (dirfd == -1) {
error_setg_errno(errp, errno, "open(\"%s\")", dirpath);
} else {
static const char fn[] = "online";
int fd;
int res;
fd = openat(dirfd, fn, sys2vcpu ? O_RDONLY : O_RDWR);
if (fd == -1) {
if (errno != ENOENT) {
error_setg_errno(errp, errno, "open(\"%s/%s\")", dirpath, fn);
} else if (sys2vcpu) {
vcpu->online = true;
vcpu->can_offline = false;
} else if (!vcpu->online) {
error_setg(errp, "logical processor #%" PRId64 " can't be "
"offlined", vcpu->logical_id);
} /* otherwise pretend successful re-onlining */
} else {
unsigned char status;
res = pread(fd, &status, 1, 0);
if (res == -1) {
error_setg_errno(errp, errno, "pread(\"%s/%s\")", dirpath, fn);
} else if (res == 0) {
error_setg(errp, "pread(\"%s/%s\"): unexpected EOF", dirpath,
fn);
} else if (sys2vcpu) {
vcpu->online = (status != '0');
vcpu->can_offline = true;
} else if (vcpu->online != (status != '0')) {
status = '0' + vcpu->online;
if (pwrite(fd, &status, 1, 0) == -1) {
error_setg_errno(errp, errno, "pwrite(\"%s/%s\")", dirpath,
fn);
}
} /* otherwise pretend successful re-(on|off)-lining */
res = close(fd);
g_assert(res == 0);
}
res = close(dirfd);
g_assert(res == 0);
}
g_free(dirpath);
}
GuestLogicalProcessorList *qmp_guest_get_vcpus(Error **errp)
{
int64_t current;
GuestLogicalProcessorList *head, **link;
long sc_max;
Error *local_err = NULL;
current = 0;
head = NULL;
link = &head;
sc_max = SYSCONF_EXACT(_SC_NPROCESSORS_CONF, &local_err);
while (local_err == NULL && current < sc_max) {
GuestLogicalProcessor *vcpu;
GuestLogicalProcessorList *entry;
vcpu = g_malloc0(sizeof *vcpu);
vcpu->logical_id = current++;
vcpu->has_can_offline = true; /* lolspeak ftw */
transfer_vcpu(vcpu, true, &local_err);
entry = g_malloc0(sizeof *entry);
entry->value = vcpu;
*link = entry;
link = &entry->next;
}
if (local_err == NULL) {
/* there's no guest with zero VCPUs */
g_assert(head != NULL);
return head;
}
qapi_free_GuestLogicalProcessorList(head);
error_propagate(errp, local_err);
return NULL;
}
#else /* defined(__linux__) */
void qmp_guest_suspend_disk(Error **err)
@ -1134,6 +1268,12 @@ GuestNetworkInterfaceList *qmp_guest_network_get_interfaces(Error **errp)
return NULL;
}
GuestLogicalProcessorList *qmp_guest_get_vcpus(Error **errp)
{
error_set(errp, QERR_UNSUPPORTED);
return NULL;
}
#endif
#if !defined(CONFIG_FSFREEZE)
@ -1167,12 +1307,6 @@ void qmp_guest_fstrim(bool has_minimum, int64_t minimum, Error **err)
}
#endif
GuestLogicalProcessorList *qmp_guest_get_vcpus(Error **errp)
{
error_set(errp, QERR_UNSUPPORTED);
return NULL;
}
int64_t qmp_guest_set_vcpus(GuestLogicalProcessorList *vcpus, Error **errp)
{
error_set(errp, QERR_UNSUPPORTED);