Re: [XEN][PATCH v11 11/20] xen/iommu: Introduce iommu_remove_dt_device()

[Stefano Stabellini <sstabellini@xxxxxxxxxx>]

On Mon, 4 Sep 2023, Michal Orzel wrote:
> On 01/09/2023 06:59, Vikram Garhwal wrote:
> > Remove master device from the IOMMU. This will be helpful when removing the
> > overlay nodes using dynamic programming during run time.
> > 
> > Signed-off-by: Vikram Garhwal <vikram.garhwal@xxxxxxx>
> > 
> > ---
> > Changes from v10:
> >     Add comment regarding return values of iommu_remove_dt_device().
> >     Add ASSERT to check if is_protected is removed or not.
> > Changes from v7:
> >     Add check if IOMMU is enabled.
> >     Fix indentation of fail.
> > ---
> > ---
> >  xen/drivers/passthrough/device_tree.c | 43 +++++++++++++++++++++++++++
> >  xen/include/xen/iommu.h               | 10 +++++++
> >  2 files changed, 53 insertions(+)
> > 
> > diff --git a/xen/drivers/passthrough/device_tree.c 
> > b/xen/drivers/passthrough/device_tree.c
> > index 687c61e7da..80f6efc606 100644
> > --- a/xen/drivers/passthrough/device_tree.c
> > +++ b/xen/drivers/passthrough/device_tree.c
> > @@ -127,6 +127,49 @@ int iommu_release_dt_devices(struct domain *d)
> >      return 0;
> >  }
> >  
> > +int iommu_remove_dt_device(struct dt_device_node *np)
> > +{
> > +    const struct iommu_ops *ops = iommu_get_ops();
> > +    struct device *dev = dt_to_dev(np);
> > +    int rc;
> > +
> > +    if ( !iommu_enabled )
> > +        return 1;
> > +
> > +    if ( !ops )
> > +        return -EOPNOTSUPP;
> > +
> > +    spin_lock(&dtdevs_lock);
> > +
> > +    if ( iommu_dt_device_is_assigned_locked(np) )
> > +    {
> > +        rc = -EBUSY;
> > +        goto fail;
> > +    }
> > +
> > +    if ( !ops->remove_device )
> > +    {
> > +        rc = -EOPNOTSUPP;
> > +        goto fail;
> > +    }
> > +
> > +    /*
> > +     * De-register the device from the IOMMU driver.
> > +     * The driver is responsible for removing is_protected flag.
> > +     */
> > +    rc = ops->remove_device(0, dev);
> > +
> > +    if ( !rc )
> > +    {
> > +        ASSERT(!dt_device_is_protected(np));
> > +        iommu_fwspec_free(dev);
> > +    }
> > +
> > + fail:
> > +    spin_unlock(&dtdevs_lock);
> > +    return rc;
> > +}
> > +
> >  int iommu_add_dt_device(struct dt_device_node *np)
> >  {
> >      const struct iommu_ops *ops = iommu_get_ops();
> > diff --git a/xen/include/xen/iommu.h b/xen/include/xen/iommu.h
> > index a18b68e247..84bd77395e 100644
> > --- a/xen/include/xen/iommu.h
> > +++ b/xen/include/xen/iommu.h
> > @@ -235,6 +235,16 @@ int iommu_add_dt_device(struct dt_device_node *np);
> >  int iommu_do_dt_domctl(struct xen_domctl *domctl, struct domain *d,
> >                         XEN_GUEST_HANDLE_PARAM(xen_domctl_t) u_domctl);
> >  
> > +/*
> > + * Helper to remove master device from the IOMMU.
> > + *
> > + * Return values:
> > + *  0 : device is de-registerd from IOMMU.
> s/registerd/registered/
> 
> > + * <0 : error while removing the device from IOMMU.
> > + * >0 : IOMMU is not enabled/present or device is not connected to it.
> The first part refers to "iommu_enabled" but I cannot see how you check for 
> the second part
> (and return >0).

Yes I would remove "or device is not connected to it". It can be done on
commit.


> Apart from that:
> Reviewed-by: Michal Orzel <michal.orzel@xxxxxxx>

Acked-by: Stefano Stabellini <sstabellini@xxxxxxxxxx>