From a103bb105c0c189c3973311ff1826972b5bc6ad6 Mon Sep 17 00:00:00 2001 From: "Daniel P. Berrange" Date: Tue, 10 Feb 2015 15:59:57 +0000 Subject: [PATCH] qemu: fix setting of VM CPU affinity with TCG If a previous commit I fixed the incorrect handling of vcpu pids for TCG mode QEMU: commit b07f3d821dfb11a118ee75ea275fd6ab737d9500 Author: Daniel P. Berrange Date: Thu Dec 18 16:34:39 2014 +0000 Don't setup fake CPU pids for old QEMU The code assumes that def->vcpus == nvcpupids, so when we setup fake CPU pids for old QEMU with nvcpupids == 1, we cause the later code to read off the end of the array. This has fun results like sche_setaffinity(0, ...) which changes libvirtd's own CPU affinity, or even better sched_setaffinity($RANDOM, ...) which changes the affinity of a random OS process. The intent was that this would merely disable the ability to set per-vCPU affinity. It should still have been possible to set VM level host CPU affinity. Unfortunately, when you set 4, the XML parser will internally take this & initialize an entry in the def->cputune.vcpupin array for every VCPU. IOW this is implicitly being treated as Even more fun, the faked cputune elements are hidden from view when querying the live XML, because their cpuset mask is the same as the VM default cpumask. The upshot was that it was impossible to set VM level CPU affinity. To fix this we must update qemuProcessSetVcpuAffinities so that it only reports a fatal error if the per-VCPU cpu mask is different from the VM level cpu mask. Signed-off-by: Daniel P. Berrange --- src/qemu/qemu_process.c | 15 ++++++++++++--- 1 file changed, 12 insertions(+), 3 deletions(-) diff --git a/src/qemu/qemu_process.c b/src/qemu/qemu_process.c index 4773120f51..43a64a16b2 100644 --- a/src/qemu/qemu_process.c +++ b/src/qemu/qemu_process.c @@ -2497,9 +2497,18 @@ qemuProcessSetVcpuAffinities(virDomainObjPtr vm) return 0; if (priv->vcpupids == NULL) { - virReportError(VIR_ERR_OPERATION_INVALID, - "%s", _("cpu affinity is not supported")); - return -1; + /* If any CPU has custom affinity that differs from the + * VM default affinity, we must reject it + */ + for (n = 0; n < def->vcpus; n++) { + if (!virBitmapEqual(def->cpumask, + def->cputune.vcpupin[n]->cpumask)) { + virReportError(VIR_ERR_OPERATION_INVALID, + "%s", _("cpu affinity is not supported")); + return -1; + } + } + return 0; } for (n = 0; n < def->vcpus; n++) { -- GitLab