Re: [PATCH v6 05/24] kvm/vfio: Accept vfio device file from userspace

Xu Yilun
2023-03-22T14:22:45Z

On 2023-03-08 at 05:28:44 -0800, Yi Liu wrote:
> This defines KVM_DEV_VFIO_FILE* and make alias with KVM_DEV_VFIO_GROUP*.
> Old userspace uses KVM_DEV_VFIO_GROUP* works as well.
>
> Signed-off-by: Yi Liu <yi.l.liu@intel.com>
> Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
> Tested-by: Terrence Xu <terrence.xu@intel.com>
> Tested-by: Nicolin Chen <nicolinc@nvidia.com>
> Tested-by: Matthew Rosato <mjrosato@linux.ibm.com>
> ---
> Documentation/virt/kvm/devices/vfio.rst | 52 +++++++++++++++++--------
> include/uapi/linux/kvm.h | 16 ++++++--
> virt/kvm/vfio.c | 16 ++++----
> 3 files changed, 55 insertions(+), 29 deletions(-)
>
> diff --git a/Documentation/virt/kvm/devices/vfio.rst b/Documentation/virt/kvm/devices/vfio.rst
> index 79b6811bb4f3..5b05b48abaab 100644
> --- a/Documentation/virt/kvm/devices/vfio.rst
> +++ b/Documentation/virt/kvm/devices/vfio.rst
> @@ -9,24 +9,37 @@ Device types supported:
> - KVM_DEV_TYPE_VFIO
>
> Only one VFIO instance may be created per VM. The created device
> -tracks VFIO groups in use by the VM and features of those groups
> -important to the correctness and acceleration of the VM. As groups
> -are enabled and disabled for use by the VM, KVM should be updated
> -about their presence. When registered with KVM, a reference to the
> -VFIO-group is held by KVM.
> +tracks VFIO files (group or device) in use by the VM and features
> +of those groups/devices important to the correctness and acceleration
> +of the VM. As groups/devices are enabled and disabled for use by the
> +VM, KVM should be updated about their presence. When registered with
> +KVM, a reference to the VFIO file is held by KVM.
>
> Groups:
> - KVM_DEV_VFIO_GROUP
> -
> -KVM_DEV_VFIO_GROUP attributes:
> - KVM_DEV_VFIO_GROUP_ADD: Add a VFIO group to VFIO-KVM device tracking
> - kvm_device_attr.addr points to an int32_t file descriptor
> - for the VFIO group.
> - KVM_DEV_VFIO_GROUP_DEL: Remove a VFIO group from VFIO-KVM device tracking
> - kvm_device_attr.addr points to an int32_t file descriptor
> - for the VFIO group.
> - KVM_DEV_VFIO_GROUP_SET_SPAPR_TCE: attaches a guest visible TCE table
> + KVM_DEV_VFIO_FILE
> + alias: KVM_DEV_VFIO_GROUP
> +
> +KVM_DEV_VFIO_FILE attributes:
> + KVM_DEV_VFIO_FILE_ADD: Add a VFIO file (group/device) to VFIO-KVM device
> + tracking
> +
> + alias: KVM_DEV_VFIO_GROUP_ADD
> +
> + kvm_device_attr.addr points to an int32_t file descriptor for the
> + VFIO file.

A blank line here to be consistent with other attibutes.

> + KVM_DEV_VFIO_FILE_DEL: Remove a VFIO file (group/device) from VFIO-KVM
> + device tracking
> +
> + alias: KVM_DEV_VFIO_GROUP_DEL
> +
> + kvm_device_attr.addr points to an int32_t file descriptor for the
> + VFIO file.
> +
> + KVM_DEV_VFIO_FILE_SET_SPAPR_TCE: attaches a guest visible TCE table
> allocated by sPAPR KVM.
> +
> + alias: KVM_DEV_VFIO_GROUP_SET_SPAPR_TCE
> +
> kvm_device_attr.addr points to a struct::
>
> struct kvm_vfio_spapr_tce {
> @@ -40,9 +53,14 @@ KVM_DEV_VFIO_GROUP attributes:
> - @tablefd is a file descriptor for a TCE table allocated via
> KVM_CREATE_SPAPR_TCE.
>
> + only accepts vfio group file as SPAPR has no iommufd support
> +
> ::
>
> -The GROUP_ADD operation above should be invoked prior to accessing the
> +The FILE/GROUP_ADD operation above should be invoked prior to accessing the
> device file descriptor via VFIO_GROUP_GET_DEVICE_FD in order to support
> drivers which require a kvm pointer to be set in their .open_device()
> -callback.
> +callback. It is the same for device file descriptor via character device
> +open which gets device access via VFIO_DEVICE_BIND_IOMMUFD. For such file
> +descriptors, FILE_ADD should be invoked before VFIO_DEVICE_BIND_IOMMUFD
> +to support the drivers mentioned in piror sentence as well.

s/piror/prior

Thanks,
Yilun