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SubjectRe: [PATCH v4 09/12] iommu/vt-d: Add iotlb flush for nested domain
From
On 2023/8/2 15:46, Tian, Kevin wrote:
>> From: Liu, Yi L <yi.l.liu@intel.com>
>> 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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