Re: [PATCH] iommu/virtio: Detach domain on endpoint release

[Jean-Philippe Brucker <jean-philippe@linaro.org>]

On Wed, May 10, 2023 at 05:37:22PM +0200, Eric Auger wrote:
> Hi Jean,
> 
> On 4/14/23 17:07, Jean-Philippe Brucker wrote:
> > When an endpoint is released, for example a PCIe VF is disabled or a
> > function hot-unplugged, it should be detached from its domain. Send a
> > DETACH request.
> >
> > Fixes: edcd69ab9a32 ("iommu: Add virtio-iommu driver")
> > Reported-by: Akihiko Odaki <akihiko.odaki@daynix.com>
> > Link: https://lore.kernel.org/all/15bf1b00-3aa0-973a-3a86-3fa5c4d41d2c@daynix.com/
> > Signed-off-by: Jean-Philippe Brucker <jean-philippe@linaro.org>
> > ---
> >  drivers/iommu/virtio-iommu.c | 23 +++++++++++++++++++++++
> >  1 file changed, 23 insertions(+)
> >
> > diff --git a/drivers/iommu/virtio-iommu.c b/drivers/iommu/virtio-iommu.c
> > index 5b8fe9bfa9a5..3d3d4462359e 100644
> > --- a/drivers/iommu/virtio-iommu.c
> > +++ b/drivers/iommu/virtio-iommu.c
> > @@ -788,6 +788,28 @@ static int viommu_attach_dev(struct iommu_domain *domain, struct device *dev)
> >  	return 0;
> >  }
> >  
> > +static void viommu_detach_dev(struct viommu_endpoint *vdev)
> > +{
> > +	int i;
> > +	struct virtio_iommu_req_detach req;
> > +	struct viommu_domain *vdomain = vdev->vdomain;
> > +	struct iommu_fwspec *fwspec = dev_iommu_fwspec_get(vdev->dev);
> > +
> > +	if (!vdomain)
> > +		return;
> > +
> > +	req = (struct virtio_iommu_req_detach) {
> > +		.head.type	= VIRTIO_IOMMU_T_DETACH,
> > +		.domain		= cpu_to_le32(vdomain->id),
> > +	};
> > +
> > +	for (i = 0; i < fwspec->num_ids; i++) {
> > +		req.endpoint = cpu_to_le32(fwspec->ids[i]);
> > +		WARN_ON(viommu_send_req_sync(vdev->viommu, &req, sizeof(req)));
> > +	}
> just a late question: don't you need to decrement vdomain's nr_endpoints?
> 

Ah yes, I'll fix that, thank you. I think attach() could use some cleanup
as well: if the request fails then we should keep the nr_endpoints
reference on the previous domain. But that's less urgent.

Thanks,
Jean

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