Re: [PATCH] xen/arm : smmuv3: Fix to handle multiple StreamIds per device.

[Stefano Stabellini <sstabellini@kernel.org>]

+IanJ

On Wed, 17 Feb 2021, Bertrand Marquis wrote:
> Hi Rahul,
> 
> 
> > On 17 Feb 2021, at 10:05, Rahul Singh <Rahul.Singh@arm.com> wrote:
> > 
> > SMMUv3 driver does not handle multiple StreamId if the master device
> > supports more than one StreamID.
> > 
> > This bug was introduced when the driver was ported from Linux to XEN.
> > dt_device_set_protected(..) should be called from add_device(..) not
> > from the dt_xlate(..).
> > 
> > Move dt_device_set_protected(..) from dt_xlate(..) to add_device().
> > 
> > Signed-off-by: Rahul Singh <rahul.singh@arm.com>
> Reviewed-by: Bertrand Marquis <bertrand.marquis@arm.com>
> 
> Thanks a lot, this is fixing issues with multiple stream ids for one device :-)

Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>


> > ---
> > This patch is a candidate for 4.15 as without this patch it is not possible to
> > assign multiple StreamIds to the same device when device is protected behind
> > SMMUv3.

I agree especially considering that the impact is limited to smmu-v3.c.


> > ---
> > xen/drivers/passthrough/arm/smmu-v3.c | 29 ++++++++++-----------------
> > 1 file changed, 11 insertions(+), 18 deletions(-)
> > 
> > diff --git a/xen/drivers/passthrough/arm/smmu-v3.c b/xen/drivers/passthrough/arm/smmu-v3.c
> > index 914cdc1cf4..53d150cdb6 100644
> > --- a/xen/drivers/passthrough/arm/smmu-v3.c
> > +++ b/xen/drivers/passthrough/arm/smmu-v3.c
> > @@ -2207,24 +2207,6 @@ static int arm_smmu_add_device(u8 devfn, struct device *dev)
> > 	 */
> > 	arm_smmu_enable_pasid(master);
> > 
> > -	return 0;
> > -
> > -err_free_master:
> > -	xfree(master);
> > -	dev_iommu_priv_set(dev, NULL);
> > -	return ret;
> > -}
> > -
> > -static int arm_smmu_dt_xlate(struct device *dev,
> > -				const struct dt_phandle_args *args)
> > -{
> > -	int ret;
> > -	struct iommu_fwspec *fwspec = dev_iommu_fwspec_get(dev);
> > -
> > -	ret = iommu_fwspec_add_ids(dev, args->args, 1);
> > -	if (ret)
> > -		return ret;
> > -
> > 	if (dt_device_is_protected(dev_to_dt(dev))) {
> > 		dev_err(dev, "Already added to SMMUv3\n");
> > 		return -EEXIST;
> > @@ -2237,6 +2219,17 @@ static int arm_smmu_dt_xlate(struct device *dev,
> > 			dev_name(fwspec->iommu_dev), fwspec->num_ids);
> > 
> > 	return 0;
> > +
> > +err_free_master:
> > +	xfree(master);
> > +	dev_iommu_priv_set(dev, NULL);
> > +	return ret;
> > +}
> > +
> > +static int arm_smmu_dt_xlate(struct device *dev,
> > +				const struct dt_phandle_args *args)
> > +{
> > +	return iommu_fwspec_add_ids(dev, args->args, 1);
> > }
> > 
> > /* Probing and initialisation functions */
> > -- 
> > 2.17.1
> > 
>