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

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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



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