[libvirt] [PATCH] qemu: ignore EACCES error on hot unplug of PCI devices with VFIO
When the hostdev managed=true, the VFIO devices are reattached to the host driver before coming to qemuTeardownHostdevCgroup(). So, the /dev/vfio/<iommu> path would not exist. We ignore the EACCES error here. Signed-off-by: Kothapally Madhu Pavan <kmp@linux.vnet.ibm.com> --- src/qemu/qemu_cgroup.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/src/qemu/qemu_cgroup.c b/src/qemu/qemu_cgroup.c index c76d585..2850346 100644 --- a/src/qemu/qemu_cgroup.c +++ b/src/qemu/qemu_cgroup.c @@ -427,7 +427,7 @@ qemuTeardownHostdevCgroup(virDomainObjPtr vm, VIR_DEBUG("Cgroup deny %s for PCI device assignment", path); rv = virCgroupDenyDevicePath(priv->cgroup, path, - VIR_CGROUP_DEVICE_RWM, false); + VIR_CGROUP_DEVICE_RWM, dev->managed); virDomainAuditCgroupPath(vm, priv->cgroup, "deny", path, "rwm", rv == 0); if (rv < 0)
On 03/07/2016 09:20 AM, Kothapally Madhu Pavan wrote:
When the hostdev managed=true, the VFIO devices are reattached to the host driver before coming to qemuTeardownHostdevCgroup(). So, the /dev/vfio/<iommu> path would not exist. We ignore the EACCES error here.
Signed-off-by: Kothapally Madhu Pavan <kmp@linux.vnet.ibm.com> --- src/qemu/qemu_cgroup.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
Can you show the error in the system log that you get when/if this fails? Using EACCES implies to a permission error. The check in virCgroupDenyDevicePath is: if (stat(path, &sb) < 0) { if (errno == EACCES && ignoreEacces) return 1; virReportSystemError(errno, _("Path '%s' is not accessible"), path); return -1; } If the path doesn't exist, then it should be a different error message (ENOENT perhaps). My other question would be, if you follow the attachment path, you'll see that if qemuHostdevPreparePCIDevices is successfully called, then qemuSetupHostdevCgroup is called after (and virCgroupAllowDevicePath is called). So, shouldn't the corollary be qemuTeardownHostdevCgroup followed by device reattachment. IOW: e.g, move the qemuTeardownHostdevCgroup in qemuDomainRemoveHostDevice to before the switch to qemuDomainRemove*HostDevice? I'd even think the StoreHostdevLabel call could move. None of the calls would head into an error path... I've posted a couple of patches which do this, see: http://www.redhat.com/archives/libvir-list/2016-March/msg01270.html John
diff --git a/src/qemu/qemu_cgroup.c b/src/qemu/qemu_cgroup.c index c76d585..2850346 100644 --- a/src/qemu/qemu_cgroup.c +++ b/src/qemu/qemu_cgroup.c @@ -427,7 +427,7 @@ qemuTeardownHostdevCgroup(virDomainObjPtr vm,
VIR_DEBUG("Cgroup deny %s for PCI device assignment", path); rv = virCgroupDenyDevicePath(priv->cgroup, path, - VIR_CGROUP_DEVICE_RWM, false); + VIR_CGROUP_DEVICE_RWM, dev->managed); virDomainAuditCgroupPath(vm, priv->cgroup, "deny", path, "rwm", rv == 0); if (rv < 0)
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Kothapally Madhu Pavan