linux/drivers/vfio, branch v4.0

vfio-pci: Add missing break to enable VFIO_PCI_ERR_IRQ_INDEX

2015-03-12T15:51:38Z

This adds a missing break statement to VFIO_DEVICE_SET_IRQS handler without which vfio_pci_set_err_trigger() would never be called. While we are here, add another "break" to VFIO_PCI_REQ_IRQ_INDEX case so if we add more indexes later, we won't miss it. Fixes: 6140a8f56238 ("vfio-pci: Add device request interface") Signed-off-by: Alexey Kardashevskiy Signed-off-by: Alex Williamson

vfio-pci: Add device request interface

2015-02-10T19:38:14Z

Userspace can opt to receive a device request notification, indicating that the device should be released. This is setup the same way as the error IRQ and also supports eventfd signaling. Future support may forcefully remove the device from the user if the request is ignored. Signed-off-by: Alex Williamson

vfio-pci: Generalize setup of simple eventfds

2015-02-10T19:37:57Z

We want another single vector IRQ index to support signaling of the device request to userspace. Generalize the error reporting IRQ index to avoid code duplication. Signed-off-by: Alex Williamson

vfio: Add and use device request op for vfio bus drivers

2015-02-10T19:37:47Z

When a request is made to unbind a device from a vfio bus driver, we need to wait for the device to become unused, ie. for userspace to release the device. However, we have a long standing TODO in the code to do something proactive to make that happen. To enable this, we add a request callback on the vfio bus driver struct, which is intended to signal the user through the vfio device interface to release the device. Instead of passively waiting for the device to become unused, we can now pester the user to give it up. Signed-off-by: Alex Williamson

vfio: Tie IOMMU group reference to vfio group

2015-02-06T22:05:06Z

Move the iommu_group reference from the device to the vfio_group. This ensures that the iommu_group persists as long as the vfio_group remains. This can be important if all of the device from an iommu_group are removed, but we still have an outstanding vfio_group reference; we can still walk the empty list of devices. Signed-off-by: Alex Williamson

vfio: Add device tracking during unbind

2015-02-06T22:05:06Z

There's a small window between the vfio bus driver calling vfio_del_group_dev() and the device being completely unbound where the vfio group appears to be non-viable. This creates a race for users like QEMU/KVM where the kvm-vfio module tries to get an external reference to the group in order to match and release an existing reference, while the device is potentially being removed from the vfio bus driver. If the group is momentarily non-viable, kvm-vfio may not be able to release the group reference until VM shutdown, making the group unusable until that point. Bridge the gap between device removal from the group and completion of the driver unbind by tracking it in a list. The device is added to the list before the bus driver reference is released and removed using the existing unbind notifier. Signed-off-by: Alex Williamson

vfio/type1: Add conditional rescheduling

2015-02-06T21:19:12Z

IOMMU operations can be expensive and it's not very difficult for a user to give us a lot of work to do for a map or unmap operation. Killing a large VM will vfio assigned devices can result in soft lockups and IOMMU tracing shows that we can easily spend 80% of our time with need-resched set. A sprinkling of conf_resched() calls after map and unmap calls has a very tiny affect on performance while resulting in traces with <1% of calls overflowing into needs- resched. Signed-off-by: Alex Williamson

vfio/type1: Chunk contiguous reserved/invalid page mappings

2015-02-06T17:59:16Z

We currently map invalid and reserved pages, such as often occur from mapping MMIO regions of a VM through the IOMMU, using single pages. There's really no reason we can't instead follow the methodology we use for normal pages and find the largest possible physically contiguous chunk for mapping. The only difference is that we don't do locked memory accounting for these since they're not back by RAM. In most applications this will be a very minor improvement, but when graphics and GPGPU devices are in play, MMIO BARs become non-trivial. Signed-off-by: Alex Williamson

vfio/type1: DMA unmap chunking

2015-02-06T17:58:56Z

When unmapping DMA entries we try to rely on the IOMMU API behavior that allows the IOMMU to unmap a larger area than requested, up to the size of the original mapping. This works great when the IOMMU supports superpages *and* they're in use. Otherwise, each PAGE_SIZE increment is unmapped separately, resulting in poor performance. Instead we can use the IOVA-to-physical-address translation provided by the IOMMU API and unmap using the largest contiguous physical memory chunk available, which is also how vfio/type1 would have mapped the region. For a synthetic 1TB guest VM mapping and shutdown test on Intel VT-d (2M IOMMU pagesize support), this achieves about a 30% overall improvement mapping standard 4K pages, regardless of IOMMU superpage enabling, and about a 40% improvement mapping 2M hugetlbfs pages when IOMMU superpages are not available. Hugetlbfs with IOMMU superpages enabled is effectively unchanged. Unfortunately the same algorithm does not work well on IOMMUs with fine-grained superpages, like AMD-Vi, costing about 25% extra since the IOMMU will automatically unmap any power-of-two contiguous mapping we've provided it. We add a routine and a domain flag to detect this feature, leaving AMD-Vi unaffected by this unmap optimization. Signed-off-by: Alex Williamson

vfio-pci: Fix the check on pci device type in vfio_pci_probe()

2015-01-07T17:29:11Z

Current vfio-pci just supports normal pci device, so vfio_pci_probe() will return if the pci device is not a normal device. While current code makes a mistake. PCI_HEADER_TYPE is the offset in configuration space of the device type, but we use this value to mask the type value. This patch fixs this by do the check directly on the pci_dev->hdr_type. Signed-off-by: Wei Yang Signed-off-by: Alex Williamson Cc: stable@vger.kernel.org # v3.6+