Re: [PATCH RFC v1 02/11] iommu/virtio: Maintain a list of endpoints served by viommu_dev

[Vivek Kumar Gautam]

On 9/21/21 9:29 PM, Jean-Philippe Brucker wrote:
> On Fri, Apr 23, 2021 at 03:21:38PM +0530, Vivek Gautam wrote:
> > Keeping a record of list of endpoints that are served by the virtio-iommu
> > device would help in redirecting the requests of page faults to the
> > correct endpoint device to handle such requests.
> >
> > Signed-off-by: Vivek Gautam <vivek.gautam@xxxxxxx>
> > ---
> >   drivers/iommu/virtio-iommu.c | 21 +++++++++++++++++++++
> >   1 file changed, 21 insertions(+)
> >
> > diff --git a/drivers/iommu/virtio-iommu.c b/drivers/iommu/virtio-iommu.c
> > index 50039070e2aa..c970f386f031 100644
> > --- a/drivers/iommu/virtio-iommu.c
> > +++ b/drivers/iommu/virtio-iommu.c
> > @@ -48,6 +48,7 @@ struct viommu_dev {
> >   	spinlock_t			request_lock;
> >   	struct list_head		requests;
> >   	void				*evts;
> > +	struct list_head		endpoints;
>
> As we're going to search by ID, an xarray or rb_tree would be more
> appropriate than a list

Sure, I will update this with a rb_tree.

> >   
> >   	/* Device configuration */
> >   	struct iommu_domain_geometry	geometry;
> > @@ -115,6 +116,12 @@ struct viommu_endpoint {
> >   	void				*pgtf;
> >   };
> >   
> > +struct viommu_ep_entry {
> > +	u32				eid;
> > +	struct viommu_endpoint		*vdev;
> > +	struct list_head		list;
> > +};
>
> No need for a separate struct, I think you can just add the list head and
> id into viommu_endpoint.

Yea right. I will update it.

> > +
> >   struct viommu_request {
> >   	struct list_head		list;
> >   	void				*writeback;
> > @@ -573,6 +580,7 @@ static int viommu_probe_endpoint(struct viommu_dev *viommu, struct device *dev)
> >   	size_t probe_len;
> >   	struct virtio_iommu_req_probe *probe;
> >   	struct virtio_iommu_probe_property *prop;
> > +	struct viommu_ep_entry *ep;
> >   	struct iommu_fwspec *fwspec = dev_iommu_fwspec_get(dev);
> >   	struct viommu_endpoint *vdev = dev_iommu_priv_get(dev);
> >   
> > @@ -640,6 +648,18 @@ static int viommu_probe_endpoint(struct viommu_dev *viommu, struct device *dev)
> >   		prop = (void *)probe->properties + cur;
> >   		type = le16_to_cpu(prop->type) & VIRTIO_IOMMU_PROBE_T_MASK;
> >   	}
> > +	if (ret)
> > +		goto out_free;
> > +
> > +	ep = kzalloc(sizeof(*ep), GFP_KERNEL);
> > +	if (!ep) {
> > +		ret = -ENOMEM;
> > +		goto out_free;
> > +	}
> > +	ep->eid = probe->endpoint;
> > +	ep->vdev = vdev;
> > +
> > +	list_add(&ep->list, &viommu->endpoints);
>
> This should be in viommu_probe_device() (viommu_probe_endpoint() is only
> called if F_PROBE is negotiated). I think we need a lock for this
> list/xarray

Sure, will fix this, and add the needed locking around.

Thanks & regards
Vivek

> Thanks,
> Jean
>
> >   
> >   out_free:
> >   	kfree(probe);
> > @@ -1649,6 +1669,7 @@ static int viommu_probe(struct virtio_device *vdev)
> >   	viommu->dev = dev;
> >   	viommu->vdev = vdev;
> >   	INIT_LIST_HEAD(&viommu->requests);
> > +	INIT_LIST_HEAD(&viommu->endpoints);
> >   
> >   	ret = viommu_init_vqs(viommu);
> >   	if (ret)
> > --
> > 2.17.1