On 01/18/2012 08:18 AM, Eric Blake wrote: 
On 01/17/2012 01:46 PM, Osier Yang wrote:

It makes one curious to see error "Failed to detach device" while
the device is detached successfully, only because of it failed
on resetting the device. And on the other hand, failed on resetting
is not the end of world, one could resolve the problem of resetting
outside of libvirt, and do reattachment then.
---
 src/qemu/qemu_hotplug.c |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/qemu/qemu_hotplug.c b/src/qemu/qemu_hotplug.c
index 4b60839..c3167ea 100644
--- a/src/qemu/qemu_hotplug.c
+++ b/src/qemu/qemu_hotplug.c
@@ -2033,11 +2033,11 @@ qemuDomainDetachHostPciDevice(struct qemud_driver *driver,
                            driver->inactivePciHostdevs) == 0)
             qemuReattachPciDevice(activePci, driver);
         else
-            ret = -1;
+            VIR_WARN("Device is detached, but failed to reset PCI device");
In here, it's just a warning for user, do we expect user to do some cleanup work
by themselves? for example, to return the pci device to host although the pci
device is attached with managed mode. if so, user must shutdown the guest
firstly then manually reattach the pci device to host.

BTW. I saw original codes do cleanup work on common branch(if ... else ...).
         pciFreeDevice(pci);
         pciFreeDevice(activePci);
     } else {
-        ret = -1;
+        VIR_WARN("Device is detached, but failed to reset PCI device");

I'm not sure about this one.  Failure to reset a PCI device could mean
that a DMA transaction could still be in flight, and be exploited to
expose memory that should not otherwise be visible.

I'd like a second opinion before pushing this.



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