RE: [PATCH v2 05/14] kvm/vfio: Accept vfio device file from userspace

Liu, Yi L
2023-02-07T08:39:35Z

> From: Tian, Kevin <kevin.tian@intel.com>
> Sent: Tuesday, February 7, 2023 11:37 AM
>
> > From: Liu, Yi L <yi.l.liu@intel.com>
> > Sent: Monday, February 6, 2023 5:05 PM
> >
> > 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>
> > ---
> > Documentation/virt/kvm/devices/vfio.rst | 40 ++++++++++++++----------
> -
> > include/uapi/linux/kvm.h | 16 +++++++---
> > virt/kvm/vfio.c | 16 +++++-----
> > 3 files changed, 42 insertions(+), 30 deletions(-)
> >
> > diff --git a/Documentation/virt/kvm/devices/vfio.rst
> > b/Documentation/virt/kvm/devices/vfio.rst
> > index 2d20dc561069..7f84ec26ca4a 100644
> > --- a/Documentation/virt/kvm/devices/vfio.rst
> > +++ b/Documentation/virt/kvm/devices/vfio.rst
> > @@ -9,23 +9,26 @@ 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:
>
> "Files"

It should be "Groups" 😊 Here "Groups" means subcmd 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 kvm_device_attr.addr points to an int32_t file descriptor
>
> "... device tracking" and "kvm_device.attr.addr points to..." are two
> sentences. They are deliberately arranged to be in different lines.

Oh, yes.

> > + for the VFIO file.
> > + - alias: KVM_DEV_VFIO_GROUP_ADD
> > + KVM_DEV_VFIO_FILE_DEL: Remove a VFIO file (group/device) from
> VFIO-
> > KVM
> > + device tracking kvm_device_attr.addr points to an int32_t file
> > + descriptor for the VFIO file.
>
> ditto

Will convert.

>
> > + - alias: KVM_DEV_VFIO_GROUP_DEL
> > + KVM_DEV_VFIO_FILE_SET_SPAPR_TCE: attaches a guest visible TCE
> table
> > allocated by sPAPR KVM.
>
> somehow here it should emphasize that the file can only be group

Yes.

> > kvm_device_attr.addr points to a struct::
> >
> > @@ -36,6 +39,7 @@ KVM_DEV_VFIO_GROUP attributes:
> >
> > where:
> >
> > - - @groupfd is a file descriptor for a VFIO group;
> > - - @tablefd is a file descriptor for a TCE table allocated via
> > - KVM_CREATE_SPAPR_TCE.
> > + *) @groupfd is a file descriptor for a VFIO group;
> > + *) @tablefd is a file descriptor for a TCE table allocated via
>
> why changing above two lines?

this is due to changing "-" to be "*)" as subbullet as below need
to add alias.

> > + KVM_CREATE_SPAPR_TCE.
> > + - alias: KVM_DEV_VFIO_FILE_SET_SPAPR_TCE
>
> GROUP

Yes.

Regards,
Yi Liu