Re: [RFC 3/7] iommufd: Add iommufd_device_bind_pasid()

[Yi Liu]

On 2023/10/10 16:19, Tian, Kevin wrote:
> > From: Liu, Yi L <yi.l.liu@xxxxxxxxx>
> > Sent: Monday, October 9, 2023 4:51 PM
> >
> > +struct iommufd_device *iommufd_device_bind_pasid(struct iommufd_ctx
> > *ictx,
> > +						 struct device *dev,
> > +						 u32 pasid, u32 *id)
> > +{
> > +	struct iommufd_device *idev;
> > +	int rc;
> > +
> > +	/*
> > +	 * iommufd always sets IOMMU_CACHE because we offer no way for
> > userspace
> > +	 * to restore cache coherency.
> > +	 */
> > +	if (!device_iommu_capable(dev, IOMMU_CAP_CACHE_COHERENCY))
> > +		return ERR_PTR(-EINVAL);
> > +
> > +	/*
> > +	 * No iommu supports pasid-granular msi message today. Here we
> > +	 * just check whether the parent device can do safe interrupts.
> > +	 * Isolation between virtual devices within the parent device
> > +	 * relies on the parent driver to enforce.
> > +	 */
> > +	if (!iommufd_selftest_is_mock_dev(dev) &&
> > +	    !msi_device_has_isolated_msi(dev)) {
> > +		rc = iommufd_allow_unsafe_interrupts(dev);
> > +		if (rc)
> > +			return ERR_PTR(rc);
> > +	}
> > +
>
> Only MemWr w/o pasid can be interpreted as an interrupt message
> then we need msi isolation to protect.

yes.

> But for SIOV all MemWr's are tagged with a pasid hence can never
> trigger an interrupt. From this angle looks this check is unnecessary.

But the interrupts out from a SIOV virtual device do not have pasid (at
least today). Seems still need a check here if we consider this bind for
a SIOV virtual device just like binding a physical device.

--
Regards,
Yi Liu