[libvirt] [PATCH] Pin guest to memory node on NUMA system

[Shivaprasad G Bhat]

The patch contains the fix for defect 1009880 reported at redhat bugzilla.

The root cause is, ever since the subcpusets(vcpu,emulator) were introduced, the paren cpuset cannot be modified to remove the nodes that are in use by the subcpusets.
The fix is to break the memory node modification into three steps as to assign new nodes into the parent first. Change the nodes in the child nodes. Then remove the old nodes on the parent node.

Signed-off-by: Shivaprasad G Bhat <sbhat at linux.vnet.ibm.com>
---
 src/qemu/qemu_driver.c |  129 ++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 129 insertions(+)

diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
index c613967..4db692e 100644
--- a/src/qemu/qemu_driver.c
+++ b/src/qemu/qemu_driver.c
@@ -8193,7 +8193,11 @@ qemuDomainSetNumaParameters(virDomainPtr dom,
             }
         } else if (STREQ(param->field, VIR_DOMAIN_NUMA_NODESET)) {
             virBitmapPtr nodeset = NULL;
+            virBitmapPtr old_nodeset = NULL;
+            virBitmapPtr temp_nodeset = NULL;
             char *nodeset_str = NULL;
+            char *old_nodeset_str = NULL;
+            char *temp_nodeset_str = NULL;
 
             if (virBitmapParse(params[i].value.s,
                                0, &nodeset,
@@ -8203,6 +8207,10 @@ qemuDomainSetNumaParameters(virDomainPtr dom,
             }
 
             if (flags & VIR_DOMAIN_AFFECT_LIVE) {
+                size_t j;
+                virCgroupPtr cgroup_vcpu = NULL;
+                virCgroupPtr cgroup_emulator = NULL;
+
                 if (vm->def->numatune.memory.mode !=
                     VIR_DOMAIN_NUMATUNE_MEM_STRICT) {
                     virReportError(VIR_ERR_OPERATION_INVALID, "%s",
@@ -8222,7 +8230,128 @@ qemuDomainSetNumaParameters(virDomainPtr dom,
                     continue;
                 }
 
+                if (virCgroupGetCpusetMems(priv->cgroup, &old_nodeset_str) < 0) {
+                    virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
+                                   _("Failed to get current system nodeset values"));
+                    virBitmapFree(nodeset);
+                    VIR_FREE(nodeset_str);
+                    ret = -1;
+                    continue;
+                }
+
+                if (virBitmapParse(old_nodeset_str, 0, &old_nodeset,
+                                   VIR_DOMAIN_CPUMASK_LEN) < 0) {
+                    virBitmapFree(nodeset);
+                    VIR_FREE(nodeset_str);
+                    VIR_FREE(old_nodeset_str);
+                    ret = -1;
+                    continue;
+                }
+
+                if ((temp_nodeset = virBitmapNewCopy(old_nodeset)) == NULL) {
+                    virBitmapFree(nodeset);
+                    VIR_FREE(nodeset_str);
+                    virBitmapFree(old_nodeset);
+                    VIR_FREE(old_nodeset_str);
+                    ret = -1;
+                    continue;
+                }
+                virBitmapFree(old_nodeset);
+                VIR_FREE(old_nodeset_str);
+
+                for (j = 0; j < caps->host.nnumaCell; j++) {
+                    bool result;
+                    if (virBitmapGetBit(nodeset, j, &result) < 0) {
+                        virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
+                                       _("Failed to get cpuset bit values"));
+                        ret = -1;
+                        break;
+                    }
+                    if (result && (virBitmapSetBit(temp_nodeset, j) < 0)) {
+                        virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
+                                       _("Failed to set temporary cpuset bit values"));
+                        ret = -1;
+                        break;
+                    }
+                }
+
+                if (ret) {
+                    virBitmapFree(nodeset);
+                    VIR_FREE(nodeset_str);
+                    virBitmapFree(temp_nodeset);
+                    continue;
+                }
+
+                if (!(temp_nodeset_str = virBitmapFormat(temp_nodeset))) {
+                    virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
+                                   _("Failed to format nodeset"));
+                    virBitmapFree(nodeset);
+                    VIR_FREE(nodeset_str);
+                    virBitmapFree(temp_nodeset);
+                    ret = -1;
+                    continue;
+                }
+
+                if (virCgroupSetCpusetMems(priv->cgroup, temp_nodeset_str) < 0) {
+                    virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
+                                   _("Failed to set cpuset values"));
+                    virBitmapFree(nodeset);
+                    VIR_FREE(nodeset_str);
+                    virBitmapFree(temp_nodeset);
+                    VIR_FREE(temp_nodeset_str);
+                    ret = -1;
+                    continue;
+                }
+
+                virBitmapFree(temp_nodeset);
+                VIR_FREE(temp_nodeset_str);
+
+                for (j = 0; j < priv->nvcpupids; j++) {
+                    if (virCgroupNewVcpu(priv->cgroup, j, false, &cgroup_vcpu) < 0) {
+                        virReportError(VIR_ERR_INTERNAL_ERROR,
+                                       _("Failed to get cpuset values for vcpu%d"), j);
+                        ret = -1;
+                        break;
+                    }
+                    if (virCgroupSetCpusetMems(cgroup_vcpu, nodeset_str) < 0) {
+                        virReportError(VIR_ERR_INTERNAL_ERROR,
+                                       _("Failed to set cpuset values for vcpu%d"), j);
+                        virCgroupFree(&cgroup_vcpu);
+                        ret = -1;
+                        break;
+                    }
+                    virCgroupFree(&cgroup_vcpu);
+                }
+
+                if (ret) {
+                    virBitmapFree(nodeset);
+                    VIR_FREE(nodeset_str);
+                    continue;
+                }
+
+                if (virCgroupNewEmulator(priv->cgroup, false, &cgroup_emulator) < 0) {
+                    virReportError(VIR_ERR_INTERNAL_ERROR, "%s"
+                                   _("Failed to get cpuset values for emulator"));
+                    virBitmapFree(nodeset);
+                    VIR_FREE(nodeset_str);
+                    ret = -1;
+                    continue;
+                }
+
+                if (virCgroupSetCpusetMems(cgroup_emulator, nodeset_str) < 0) {
+                    virReportError(VIR_ERR_INTERNAL_ERROR, "%s"
+                                   _("Failed to set cpuset values for emulator"));
+                    virBitmapFree(nodeset);
+                    VIR_FREE(nodeset_str);
+                    virCgroupFree(&cgroup_emulator);
+                    ret = -1;
+                    continue;
+                }
+                virCgroupFree(&cgroup_emulator);
+
                 if (virCgroupSetCpusetMems(priv->cgroup, nodeset_str) < 0) {
+                    virReportError(VIR_ERR_INTERNAL_ERROR, "%s"
+                                   _("Failed to set cpuset"));
                     virBitmapFree(nodeset);
                     VIR_FREE(nodeset_str);
                     ret = -1;