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vfio-pci: PCI hot reset interface

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The current VFIO_DEVICE_RESET interface only maps to PCI use cases
where we can isolate the reset to the individual PCI function.  This
means the device must support FLR (PCIe or AF), PM reset on D3hot->D0
transition, device specific reset, or be a singleton device on a bus
for a secondary bus reset.  FLR does not have widespread support,
PM reset is not very reliable, and bus topology is dictated by the
system and device design.  We need to provide a means for a user to
induce a bus reset in cases where the existing mechanisms are not
available or not reliable.

This device specific extension to VFIO provides the user with this
ability.  Two new ioctls are introduced:
 - VFIO_DEVICE_PCI_GET_HOT_RESET_INFO
 - VFIO_DEVICE_PCI_HOT_RESET

The first provides the user with information about the extent of
devices affected by a hot reset.  This is essentially a list of
devices and the IOMMU groups they belong to.  The user may then
initiate a hot reset by calling the second ioctl.  We must be
careful that the user has ownership of all the affected devices
found via the first ioctl, so the second ioctl takes a list of file
descriptors for the VFIO groups affected by the reset.  Each group
must have IOMMU protection established for the ioctl to succeed.

Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
This commit is contained in:
Alex Williamson 2013-09-04 11:28:04 -06:00
commit 8b27ee60bf
2 changed files with 323 additions and 1 deletions
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38
include/uapi/linux/vfio.h
View file

@ -324,6 +324,44 @@ enum {
VFIO_PCI_NUM_IRQS
};
/**
* VFIO_DEVICE_GET_PCI_HOT_RESET_INFO - _IORW(VFIO_TYPE, VFIO_BASE + 12,
* struct vfio_pci_hot_reset_info)
*
* Return: 0 on success, -errno on failure:
* -enospc = insufficient buffer, -enodev = unsupported for device.
*/
struct vfio_pci_dependent_device {
__u32 group_id;
__u16 segment;
__u8 bus;
__u8 devfn; /* Use PCI_SLOT/PCI_FUNC */
};
struct vfio_pci_hot_reset_info {
__u32 argsz;
__u32 flags;
__u32 count;
struct vfio_pci_dependent_device devices[];
};
#define VFIO_DEVICE_GET_PCI_HOT_RESET_INFO _IO(VFIO_TYPE, VFIO_BASE + 12)
/**
* VFIO_DEVICE_PCI_HOT_RESET - _IOW(VFIO_TYPE, VFIO_BASE + 13,
* struct vfio_pci_hot_reset)
*
* Return: 0 on success, -errno on failure.
*/
struct vfio_pci_hot_reset {
__u32 argsz;
__u32 flags;
__u32 count;
__s32 group_fds[];
};
#define VFIO_DEVICE_PCI_HOT_RESET _IO(VFIO_TYPE, VFIO_BASE + 13)
/* -------- API for Type1 VFIO IOMMU -------- */
/**