linux-kernel - Re: [RFC v1 3/8] vhost: Add 3 new uapi to support iommufd

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Message-ID: <CACGkMEsp_rg+_01hwxCtZNOk2itB1L89mdOc1W1DG3umfEt5bw@mail.gmail.com>
Date:   Wed, 8 Nov 2023 11:03:12 +0800
From:   Jason Wang <jasowang@...hat.com>
To:     Cindy Lu <lulu@...hat.com>
Cc:     mst@...hat.com, yi.l.liu@...el.com, jgg@...dia.com,
        linux-kernel@...r.kernel.org,
        virtualization@...ts.linux-foundation.org, netdev@...r.kernel.org
Subject: Re: [RFC v1 3/8] vhost: Add 3 new uapi to support iommufd

On Tue, Nov 7, 2023 at 2:57 PM Cindy Lu <lulu@...hat.com> wrote:
>
> On Mon, Nov 6, 2023 at 3:30 PM Jason Wang <jasowang@...hat.com> wrote:
> >
> > On Sat, Nov 4, 2023 at 1:17 AM Cindy Lu <lulu@...hat.com> wrote:
> > >
> > > VHOST_VDPA_SET_IOMMU_FD: bind the device to iommufd device
> > >
> > > VDPA_DEVICE_ATTACH_IOMMUFD_AS: Attach a vdpa device to an iommufd
> > > address space specified by IOAS id.
> > >
> > > VDPA_DEVICE_DETACH_IOMMUFD_AS: Detach a vdpa device
> > > from the iommufd address space
> > >
> > > Signed-off-by: Cindy Lu <lulu@...hat.com>
> > > ---
> >
> > [...]
> >
> > > diff --git a/include/uapi/linux/vhost.h b/include/uapi/linux/vhost.h
> > > index f5c48b61ab62..07e1b2c443ca 100644
> > > --- a/include/uapi/linux/vhost.h
> > > +++ b/include/uapi/linux/vhost.h
> > > @@ -219,4 +219,70 @@
> > >   */
> > >  #define VHOST_VDPA_RESUME              _IO(VHOST_VIRTIO, 0x7E)
> > >
> > > +/* vhost_vdpa_set_iommufd
> > > + * Input parameters:
> > > + * @iommufd: file descriptor from /dev/iommu; pass -1 to unset
> > > + * @iommufd_ioasid: IOAS identifier returned from ioctl(IOMMU_IOAS_ALLOC)
> > > + * Output parameters:
> > > + * @out_dev_id: device identifier
> > > + */
> > > +struct vhost_vdpa_set_iommufd {
> > > +       __s32 iommufd;
> > > +       __u32 iommufd_ioasid;
> > > +       __u32 out_dev_id;
> > > +};
> > > +
> > > +#define VHOST_VDPA_SET_IOMMU_FD \
> > > +       _IOW(VHOST_VIRTIO, 0x7F, struct vhost_vdpa_set_iommufd)
> > > +
> > > +/*
> > > + * VDPA_DEVICE_ATTACH_IOMMUFD_AS -
> > > + * _IOW(VHOST_VIRTIO, 0x7f, struct vdpa_device_attach_iommufd_as)
> > > + *
> > > + * Attach a vdpa device to an iommufd address space specified by IOAS
> > > + * id.
> > > + *
> > > + * Available only after a device has been bound to iommufd via
> > > + * VHOST_VDPA_SET_IOMMU_FD
> > > + *
> > > + * Undo by VDPA_DEVICE_DETACH_IOMMUFD_AS or device fd close.
> > > + *
> > > + * @argsz:     user filled size of this data.
> > > + * @flags:     must be 0.
> > > + * @ioas_id:   Input the target id which can represent an ioas
> > > + *             allocated via iommufd subsystem.
> > > + *
> > > + * Return: 0 on success, -errno on failure.
> > > + */
> > > +struct vdpa_device_attach_iommufd_as {
> > > +       __u32 argsz;
> > > +       __u32 flags;
> > > +       __u32 ioas_id;
> > > +};
> >
> > I think we need to map ioas to vDPA AS, so there should be an ASID
> > from the view of vDPA?
> >
> > Thanks
> >
> The qemu will have a structure save and  maintain this information,So
> I didn't add this
>  in kernel，we can add this but maybe only for check?

I meant for example, a simulator has two AS. How can we attach an ioas
to a specific AS with the above uAPI?

Thanks

> this in
> Thanks
> Cindy
> > > +
> > > +#define VDPA_DEVICE_ATTACH_IOMMUFD_AS \
> > > +       _IOW(VHOST_VIRTIO, 0x82, struct vdpa_device_attach_iommufd_as)
> > > +
> > > +/*
> > > + * VDPA_DEVICE_DETACH_IOMMUFD_AS
> > > + *
> > > + * Detach a vdpa device from the iommufd address space it has been
> > > + * attached to. After it, device should be in a blocking DMA state.
> > > + *
> > > + * Available only after a device has been bound to iommufd via
> > > + * VHOST_VDPA_SET_IOMMU_FD
> > > + *
> > > + * @argsz:     user filled size of this data.
> > > + * @flags:     must be 0.
> > > + *
> > > + * Return: 0 on success, -errno on failure.
> > > + */
> > > +struct vdpa_device_detach_iommufd_as {
> > > +       __u32 argsz;
> > > +       __u32 flags;
> > > +};
> > > +
> > > +#define VDPA_DEVICE_DETACH_IOMMUFD_AS \
> > > +       _IOW(VHOST_VIRTIO, 0x83, struct vdpa_device_detach_iommufd_as)
> > > +
> > >  #endif
> > > --
> > > 2.34.3
> > >
> >
>