[libvirt PATCH] qemu: prevent attempts to detach a device on a controller with hotplug='off'

Laine Stump laine at redhat.com
Thu May 14 18:12:38 UTC 2020


Although the original patches to support controllers with
hotplug='off' were checking during hotplug/attach requests that the
device was being plugged into a PCI controller that didn't have
hotplug disabled, but I forgot to do the same for device detach (the
main impetus for adding the feature was to prevent unplugs originating
from within the guest, so it slipped my mind). So although the guest
OS was ultimately unable to honor the unplug request, libvirt could
still be used to make such a request, and since device attach/detach
are asynchronous operations, the caller to libvirt would receive a
success status back (the device would stubbornly/correctly remain in
the domain status XML however)

This patch remedies that, by looking at the controller for the device
in the detach request, and immediately failing the operation if that
controller has hotplug=off.

r changes. Lines starting

Signed-off-by: Laine Stump <laine at redhat.com>
---
 src/qemu/qemu_hotplug.c | 27 +++++++++++++++++++++++++++
 1 file changed, 27 insertions(+)

diff --git a/src/qemu/qemu_hotplug.c b/src/qemu/qemu_hotplug.c
index ab5a7aef84..5fe125b1a7 100644
--- a/src/qemu/qemu_hotplug.c
+++ b/src/qemu/qemu_hotplug.c
@@ -5891,6 +5891,33 @@ qemuDomainDetachDeviceLive(virDomainObjPtr vm,
         return -1;
     }
 
+    if (info->type == VIR_DOMAIN_DEVICE_ADDRESS_TYPE_PCI) {
+        int controllerIdx = virDomainControllerFind(vm->def,
+                                                    VIR_DOMAIN_CONTROLLER_TYPE_PCI,
+                                                    info->addr.pci.bus);
+        if (controllerIdx < 0) {
+            virReportError(VIR_ERR_OPERATION_FAILED,
+                           _("cannot hot unplug %s device with PCI guest address: "
+                             VIR_PCI_DEVICE_ADDRESS_FMT
+                             " - controller not found"),
+                           virDomainDeviceTypeToString(detach.type),
+                           info->addr.pci.domain, info->addr.pci.bus,
+                           info->addr.pci.slot, info->addr.pci.function);
+            return -1;
+        }
+
+        if (vm->def->controllers[controllerIdx]->opts.pciopts.hotplug
+            == VIR_TRISTATE_SWITCH_OFF) {
+            virReportError(VIR_ERR_OPERATION_FAILED,
+                           _("cannot hot unplug %s device with PCI guest address: "
+                             VIR_PCI_DEVICE_ADDRESS_FMT
+                             " - not allowed by controller"),
+                           virDomainDeviceTypeToString(detach.type),
+                           info->addr.pci.domain, info->addr.pci.bus,
+                           info->addr.pci.slot, info->addr.pci.function);
+            return -1;
+        }
+    }
     /*
      * Issue the qemu monitor command to delete the device (based on
      * its alias), and optionally wait a short time in case the
-- 
2.25.4




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