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qemu: monitor: Add algorithm for combining query-(hotpluggable-)-cpus data

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For hotplug purposes it's necessary to retrieve data using
query-hotpluggable-cpus while the old query-cpus API report thread IDs
and order of hotplug.

This patch adds code that merges the data using a rather non-trivial
algorithm and fills the data to the qemuMonitorCPUInfo structure for
adding to appropriate place in the domain definition.
This commit is contained in:
Peter Krempa 2016-08-01 13:56:23 +02:00
parent 1213f0f8a5
commit 9bbbc88a8f
3 changed files with 220 additions and 10 deletions
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2
src/qemu/qemu_domain.c
View File

@ -5804,7 +5804,7 @@ qemuDomainRefreshVcpuInfo(virQEMUDriverPtr driver,
if (qemuDomainObjEnterMonitorAsync(driver, vm, asyncJob) < 0)
return -1;
rc = qemuMonitorGetCPUInfo(qemuDomainGetMonitor(vm), &info, maxvcpus);
rc = qemuMonitorGetCPUInfo(qemuDomainGetMonitor(vm), &info, maxvcpus, false);
if (qemuDomainObjExitMonitor(driver, vm) < 0)
goto cleanup;

205
src/qemu/qemu_monitor.c
View File

@ -1656,13 +1656,36 @@ qemuMonitorSystemReset(qemuMonitorPtr mon)
}
static void
qemuMonitorCPUInfoClear(qemuMonitorCPUInfoPtr cpus,
size_t ncpus)
{
size_t i;
for (i = 0; i < ncpus; i++) {
cpus[i].id = 0;
cpus[i].socket_id = -1;
cpus[i].core_id = -1;
cpus[i].thread_id = -1;
cpus[i].vcpus = 0;
cpus[i].tid = 0;
VIR_FREE(cpus[i].qom_path);
VIR_FREE(cpus[i].alias);
VIR_FREE(cpus[i].type);
}
}
void
qemuMonitorCPUInfoFree(qemuMonitorCPUInfoPtr cpus,
size_t ncpus ATTRIBUTE_UNUSED)
size_t ncpus)
{
if (!cpus)
return;
qemuMonitorCPUInfoClear(cpus, ncpus);
VIR_FREE(cpus);
}
@ -1682,11 +1705,157 @@ qemuMonitorQueryCpusFree(struct qemuMonitorQueryCpusEntry *entries,
}
/**
* Legacy approach doesn't allow out of order cpus, thus no complex matching
* algorithm is necessary */
static void
qemuMonitorGetCPUInfoLegacy(struct qemuMonitorQueryCpusEntry *cpuentries,
size_t ncpuentries,
qemuMonitorCPUInfoPtr vcpus,
size_t maxvcpus)
{
size_t i;
for (i = 0; i < maxvcpus; i++) {
if (i < ncpuentries)
vcpus[i].tid = cpuentries[i].tid;
/* for legacy hotplug to work we need to fake the vcpu count added by
* enabling a given vcpu */
vcpus[i].vcpus = 1;
}
}
/**
* qemuMonitorGetCPUInfoHotplug:
*
* This function stitches together data retrieved via query-hotpluggable-cpus
* which returns entities on the hotpluggable level (which may describe more
* than one guest logical vcpu) with the output of query-cpus, having an entry
* per enabled guest logical vcpu.
*
* query-hotpluggable-cpus conveys following information:
* - topology information and number of logical vcpus this entry creates
* - device type name of the entry that needs to be used when hotplugging
* - qom path in qemu which can be used to map the entry against query-cpus
*
* query-cpus conveys following information:
* - thread id of a given guest logical vcpu
* - order in which the vcpus were inserted
* - qom path to allow mapping the two together
*
* The libvirt's internal structure has an entry for each possible (even
* disabled) guest vcpu. The purpose is to map the data together so that we are
* certain of the thread id mapping and the information required for vcpu
* hotplug.
*
* This function returns 0 on success and -1 on error, but does not report
* libvirt errors so that fallback approach can be used.
*/
static int
qemuMonitorGetCPUInfoHotplug(struct qemuMonitorQueryHotpluggableCpusEntry *hotplugvcpus,
size_t nhotplugvcpus,
struct qemuMonitorQueryCpusEntry *cpuentries,
size_t ncpuentries,
qemuMonitorCPUInfoPtr vcpus,
size_t maxvcpus)
{
char *tmp;
int order = 1;
size_t totalvcpus = 0;
size_t i;
size_t j;
/* ensure that the total vcpu count reported by query-hotpluggable-cpus equals
* to the libvirt maximum cpu count */
for (i = 0; i < nhotplugvcpus; i++)
totalvcpus += hotplugvcpus[i].vcpus;
/* trim '/thread...' suffix from the data returned by query-cpus */
for (i = 0; i < ncpuentries; i++) {
if (cpuentries[i].qom_path &&
(tmp = strstr(cpuentries[i].qom_path, "/thread")))
*tmp = '\0';
}
if (totalvcpus != maxvcpus) {
VIR_DEBUG("expected '%zu' total vcpus got '%zu'", maxvcpus, totalvcpus);
return -1;
}
/* Note the order in which the hotpluggable entities are inserted by
* matching them to the query-cpus entries */
for (i = 0; i < ncpuentries; i++) {
for (j = 0; j < nhotplugvcpus; j++) {
if (!cpuentries[i].qom_path ||
!hotplugvcpus[j].qom_path ||
STRNEQ(cpuentries[i].qom_path, hotplugvcpus[j].qom_path))
continue;
/* add ordering info for hotpluggable entries */
if (hotplugvcpus[j].enable_id == 0)
hotplugvcpus[j].enable_id = order++;
break;
}
}
/* transfer appropriate data from the hotpluggable list to corresponding
* entries. the entries returned by qemu may in fact describe multiple
* logical vcpus in the guest */
j = 0;
for (i = 0; i < nhotplugvcpus; i++) {
vcpus[j].socket_id = hotplugvcpus[i].socket_id;
vcpus[j].core_id = hotplugvcpus[i].core_id;
vcpus[j].thread_id = hotplugvcpus[i].thread_id;
vcpus[j].vcpus = hotplugvcpus[i].vcpus;
VIR_STEAL_PTR(vcpus[j].qom_path, hotplugvcpus[i].qom_path);
VIR_STEAL_PTR(vcpus[j].alias, hotplugvcpus[i].alias);
VIR_STEAL_PTR(vcpus[j].type, hotplugvcpus[i].type);
vcpus[j].id = hotplugvcpus[i].enable_id;
/* skip over vcpu entries covered by this hotpluggable entry */
j += hotplugvcpus[i].vcpus;
}
/* match entries from query cpus to the output array taking into account
* multi-vcpu objects */
for (j = 0; j < ncpuentries; j++) {
/* find the correct entry or beginning of group of entries */
for (i = 0; i < maxvcpus; i++) {
if (cpuentries[j].qom_path && vcpus[i].qom_path &&
STREQ(cpuentries[j].qom_path, vcpus[i].qom_path))
break;
}
if (i == maxvcpus) {
VIR_DEBUG("too many query-cpus entries for a given "
"query-hotpluggable-cpus entry");
return -1;
}
if (vcpus[i].vcpus != 1) {
/* find a possibly empty vcpu thread for core granularity systems */
for (; i < maxvcpus; i++) {
if (vcpus[i].tid == 0)
break;
}
}
vcpus[i].tid = cpuentries[j].tid;
}
return 0;
}
/**
* qemuMonitorGetCPUInfo:
* @mon: monitor
* @vcpus: pointer filled by array of qemuMonitorCPUInfo structures
* @maxvcpus: total possible number of vcpus
* @hotplug: query data relevant for hotplug support
*
* Detects VCPU information. If qemu doesn't support or fails reporting
* information this function will return success as other parts of libvirt
@ -1698,20 +1867,32 @@ qemuMonitorQueryCpusFree(struct qemuMonitorQueryCpusEntry *entries,
int
qemuMonitorGetCPUInfo(qemuMonitorPtr mon,
qemuMonitorCPUInfoPtr *vcpus,
size_t maxvcpus)
size_t maxvcpus,
bool hotplug)
{
qemuMonitorCPUInfoPtr info = NULL;
struct qemuMonitorQueryHotpluggableCpusEntry *hotplugcpus = NULL;
size_t nhotplugcpus = 0;
struct qemuMonitorQueryCpusEntry *cpuentries = NULL;
size_t ncpuentries = 0;
size_t i;
int ret = -1;
int rc;
qemuMonitorCPUInfoPtr info = NULL;
QEMU_CHECK_MONITOR(mon);
if (hotplug)
QEMU_CHECK_MONITOR_JSON(mon);
else
QEMU_CHECK_MONITOR(mon);
if (VIR_ALLOC_N(info, maxvcpus) < 0)
return -1;
/* initialize a few non-zero defaults */
qemuMonitorCPUInfoClear(info, maxvcpus);
if (hotplug &&
(qemuMonitorJSONGetHotpluggableCPUs(mon, &hotplugcpus, &nhotplugcpus)) < 0)
goto cleanup;
if (mon->json)
rc = qemuMonitorJSONQueryCPUs(mon, &cpuentries, &ncpuentries);
else
@ -1726,15 +1907,23 @@ qemuMonitorGetCPUInfo(qemuMonitorPtr mon,
goto cleanup;
}
for (i = 0; i < ncpuentries; i++)
info[i].tid = cpuentries[i].tid;
if (!hotplugcpus ||
qemuMonitorGetCPUInfoHotplug(hotplugcpus, nhotplugcpus,
cpuentries, ncpuentries,
info, maxvcpus) < 0) {
/* Fallback to the legacy algorithm. Hotplug paths will make sure that
* the apropriate data is present */
qemuMonitorCPUInfoClear(info, maxvcpus);
qemuMonitorGetCPUInfoLegacy(cpuentries, ncpuentries, info, maxvcpus);
}
VIR_STEAL_PTR(*vcpus, info);
ret = 0;
cleanup:
qemuMonitorCPUInfoFree(info, maxvcpus);
qemuMonitorQueryHotpluggableCpusFree(hotplugcpus, nhotplugcpus);
qemuMonitorQueryCpusFree(cpuentries, ncpuentries);
qemuMonitorCPUInfoFree(info, maxvcpus);
return ret;
}

23
src/qemu/qemu_monitor.h
View File

@ -409,6 +409,9 @@ struct qemuMonitorQueryHotpluggableCpusEntry {
int socket_id;
int core_id;
int thread_id;
/* internal data */
int enable_id;
};
void qemuMonitorQueryHotpluggableCpusFree(struct qemuMonitorQueryHotpluggableCpusEntry *entries,
size_t nentries);
@ -416,6 +419,23 @@ void qemuMonitorQueryHotpluggableCpusFree(struct qemuMonitorQueryHotpluggableCpu
struct _qemuMonitorCPUInfo {
pid_t tid;
int id; /* order of enabling of the given cpu */
/* topology info for hotplug purposes. Hotplug of given vcpu impossible if
* all entries are -1 */
int socket_id;
int core_id;
int thread_id;
unsigned int vcpus; /* number of vcpus added if given entry is hotplugged */
/* name of the qemu type to add in case of hotplug */
char *type;
/* alias of an hotpluggable entry. Entries with alias can be hot-unplugged */
char *alias;
/* internal for use in the matching code */
char *qom_path;
};
typedef struct _qemuMonitorCPUInfo qemuMonitorCPUInfo;
typedef qemuMonitorCPUInfo *qemuMonitorCPUInfoPtr;
@ -424,7 +444,8 @@ void qemuMonitorCPUInfoFree(qemuMonitorCPUInfoPtr list,
size_t nitems);
int qemuMonitorGetCPUInfo(qemuMonitorPtr mon,
qemuMonitorCPUInfoPtr *vcpus,
size_t maxvcpus);
size_t maxvcpus,
bool hotplug);
int qemuMonitorGetVirtType(qemuMonitorPtr mon,
virDomainVirtType *virtType);