Messages in this thread | | | Subject | Re: [Patch v4 21/23] x86/PCI: Refine the way to release PCI IRQ resources | From | Alex Williamson <> | Date | Wed, 04 Mar 2015 16:48:43 -0700 |
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On Wed, 2015-03-04 at 09:06 -0700, Alex Williamson wrote: > Hi, > > I'm getting a regression from this patch when using VFIO for device > assignment to a QEMU VM. I have a device initially bound to the nouveau > driver, which is unbound from that driver and bound to vfio-pci for use > by userspace. vfio-pci calls pci_enable_device, but when userspace > attempts to setup the legacy INTx interrupt, pci_dev->irq is zero and > vfio-pci errors with -ENODEV. > > Where is pci_dev->irq supposed to be getting re-initialized in this > case? Am I missing an important initialization step in vfio-pci? I > certainly don't think I should be calling request_irq(pci_dev->irq, ... > when pci_dev->irq is zero. Thanks,
It looks like the imbalance is in pci_dev->enable_cnt. Any call to pci_disable_device() will clear pci_dev->irq, but pci_enable_device() does effectively nothing unless it's called with enable_cnt == zero. So I'm at the mercy of the previous driver behaving relatively sanely in order to re-enable legacy interrupts for a device :-\ Maybe the unbound notifier needs to do some sanitizing of the device? Thanks,
Alex
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