> From: Alex Williamson <alex.williamson@xxxxxxxxxx>
> Sent: Tuesday, February 14, 2023 7:22 AM
>
> On Mon, 13 Feb 2023 07:13:36 -0800
> Yi Liu <yi.l.liu@xxxxxxxxx> wrote:
>
> > This makes the vfio file kAPIs to accepte vfio device files, also a
> > preparation for vfio device cdev support.
> >
> > For the kvm set with vfio device file, kvm pointer is stored in struct
> > vfio_device_file, and use kvm_ref_lock to protect kvm set and kvm
> > pointer usage within VFIO. This kvm pointer will be set to vfio_device
> > after device file is bound to iommufd in the cdev path.
> >
> > Signed-off-by: Yi Liu <yi.l.liu@xxxxxxxxx>
> > Reviewed-by: Kevin Tian <kevin.tian@xxxxxxxxx>
> > ---
> > drivers/vfio/vfio.h | 2 ++
> > drivers/vfio/vfio_main.c | 51
> ++++++++++++++++++++++++++++++++++++----
> > 2 files changed, 49 insertions(+), 4 deletions(-)
>
> This subtly changes the behavior of the vfio-pci hot reset functions
> without updating the uAPI description or implementation to use less
> group-centric variables. The new behavior appears to be that cdev fds
> can also be passed to prove ownership of the affected set of devices
> for a hot reset, but this probably needs to be examined for gaps.
Yes. user could pass cdev fds afterward. I suppose the VFIO_DEVICE_GET_PCI_HOT_RESET_INFO
will report the existing info (group_id, segment, bus, devfn). While userspace
passes device fds to the kernel for resetting. Need to update struct vfio_pci_hot_reset
and the kernel reset code accordingly. Probably, it is a following series for it. 😊
/**
* VFIO_DEVICE_GET_PCI_HOT_RESET_INFO - _IOWR(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)
