Re: [PATCH v4 09/12] iommu/vt-d: Add iotlb flush for nested domain

[Baolu Lu]

On 2023/8/2 15:46, Tian, Kevin wrote:
> > From: Liu, Yi L <yi.l.liu@xxxxxxxxx>
> > Sent: Monday, July 24, 2023 7:14 PM
> >
> > +static int intel_nested_cache_invalidate_user(struct iommu_domain
> > *domain,
> > +					      void *user_data)
> > +{
> > +	struct iommu_hwpt_vtd_s1_invalidate_desc *req = user_data;
> > +	struct iommu_hwpt_vtd_s1_invalidate *inv_info = user_data;
> > +	struct dmar_domain *dmar_domain = to_dmar_domain(domain);
> > +	unsigned int entry_size = inv_info->entry_size;
> > +	u64 uptr = inv_info->inv_data_uptr;
> > +	u64 nr_uptr = inv_info->entry_nr_uptr;
> > +	struct device_domain_info *info;
> > +	u32 entry_nr, index;
> > +	unsigned long flags;
> > +	int ret = 0;
> > +
> > +	if (get_user(entry_nr, (uint32_t __user *)u64_to_user_ptr(nr_uptr)))
> > +		return -EFAULT;
> > +
> > +	for (index = 0; index < entry_nr; index++) {
> > +		ret = copy_struct_from_user(req, sizeof(*req),
> > +					    u64_to_user_ptr(uptr + index *
> > entry_size),
> > +					    entry_size);
>
> If continuing this direction then the driver should also check minsz etc.
> for struct iommu_hwpt_vtd_s1_invalidate and iommu_hwpt_vtd_s1_invalidate_desc
> since they are uAPI and subject to change.

Agreed.

> > +		if (ret) {
> > +			pr_err_ratelimited("Failed to fetch invalidation
> > request\n");
> > +			break;
> > +		}
> > +
> > +		if (req->__reserved || (req->flags &
> > ~IOMMU_VTD_QI_FLAGS_LEAF) ||
> > +		    !IS_ALIGNED(req->addr, VTD_PAGE_SIZE)) {
> > +			ret = -EINVAL;
> > +			break;
> > +		}
> > +
> > +		spin_lock_irqsave(&dmar_domain->lock, flags);
> > +		list_for_each_entry(info, &dmar_domain->devices, link)
> > +			intel_nested_invalidate(info->dev, dmar_domain,
> > +						req->addr, req->npages);
> > +		spin_unlock_irqrestore(&dmar_domain->lock, flags);
>
> Disabling interrupt while invalidating iotlb is certainly unacceptable.
>
> Actually there is no need to walk devices. Under dmar_domain there
> is already a list of attached iommu's.

Walking device is only necessary when invalidating device TLB. For iotlb
invalidation, it only needs to know the iommu's.

Best regards,
baolu