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path: root/hw/vfio_pci_int.h
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2012-10-08vfio-pci: Roll the header into the .c fileAlex Williamson
It's only ~100 lines and nobody else should be using this. Suggested by Michael Tsirkin. Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
2012-10-08vfio-pci: Update slow path INTx algorithmAlex Williamson
We can't afford the overhead of switching out and back into mmap mode around each interrupt, but we can do it lazily via a timer. On INTx interrupt, disable the mmap'd memory regions and set a timer. On every interrupt, push the timer out. If the timer expires and the interrupt is no longer pending, switch back to mmap mode. This has the benefit that things like graphics cards, which rarely or never, fire an interrupt don't need manual user intervention to add the x-intx=off parameter. They'll just remain in mmap mode until they trigger an interrupt, and if they don't continue to regularly fire interrupts, they'll switch back. The default timeout is tuned for network cards so that a ping is just enough to keep them in non-mmap mode, where they have much better latency. It is tunable with an experimental option, x-intx-mmap-timeout-ms. A value of 0 keeps the device in non-mmap mode after the first interrupt. It's possible we could look at the class code of devices and come up with reasonable per-class defaults based on expected interrupt frequency and latency. None of this is used for MSI interrupts and also won't be used if we can bypass through KVM. Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
2012-10-01vfio: vfio-pci device assignment driverAlex Williamson
This adds the core of the QEMU VFIO-based PCI device assignment driver. To make use of this driver, enable CONFIG_VFIO, CONFIG_VFIO_IOMMU_TYPE1, and CONFIG_VFIO_PCI in your host Linux kernel config. Load the vfio-pci module. To assign device 0000:05:00.0 to a guest, do the following: for dev in $(ls /sys/bus/pci/devices/0000:05:00.0/iommu_group/devices); do vendor=$(cat /sys/bus/pci/devices/$dev/vendor) device=$(cat /sys/bus/pci/devices/$dev/device) if [ -e /sys/bus/pci/devices/$dev/driver ]; then echo $dev > /sys/bus/pci/devices/$dev/driver/unbind fi echo $vendor $device > /sys/bus/pci/drivers/vfio-pci/new_id done See Documentation/vfio.txt in the Linux kernel tree for further description of IOMMU groups and VFIO. Then launch qemu including the option: -device vfio-pci,host=0000:05:00.0 Legacy PCI interrupts (INTx) currently makes use of a kludge where we trap BAR accesses and assume the access is in response to an interrupt, therefore de-asserting and unmasking the interrupt. It's not quite as targetted as using the EOI for this, but it's self contained and seems to work across all architectures. The side-effect is a significant performance slow-down for device in INTx mode. Some devices, like graphics cards, don't really use their interrupt, so this can be turned off with the x-intx=off option, which disables INTx alltogether. This should be considered an experimental option until we refine this code. Both MSI and MSI-X are supported and avoid these issues. Signed-off-by: Alex Williamson <alex.williamson@redhat.com> Acked-by: Michael S. Tsirkin <mst@redhat.com> Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>