On 2022/8/18 21:41, Jason Gunthorpe wrote:
On Wed, Aug 17, 2022 at 09:20:20AM +0800, Lu Baolu wrote:
+
+/**
+ * iommu_sva_bind_device() - Bind a process address space to a device
+ * @dev: the device
+ * @mm: the mm to bind, caller must hold a reference to mm_users
+ *
+ * Create a bond between device and address space, allowing the device to access
+ * the mm using the returned PASID. If a bond already exists between @device and
+ * @mm, it is returned and an additional reference is taken. Caller must call
+ * iommu_sva_unbind_device() to release each reference.
+ *
+ * iommu_dev_enable_feature(dev, IOMMU_DEV_FEAT_SVA) must be called first, to
+ * initialize the required SVA features.
+ *
+ * On error, returns an ERR_PTR value.
+ */
+struct iommu_sva *iommu_sva_bind_device(struct device *dev, struct mm_struct *mm)
+{
+ struct iommu_domain *domain;
+ struct iommu_sva *bond;
This is called handle below, pick one name please
Updated.
+ ioasid_t max_pasids;
+ int ret;
+
+ max_pasids = dev->iommu->max_pasids;
+ if (!max_pasids)
+ return ERR_PTR(-EOPNOTSUPP);
+
+ /* Allocate mm->pasid if necessary. */
+ ret = iommu_sva_alloc_pasid(mm, 1, max_pasids - 1);
+ if (ret)
+ return ERR_PTR(ret);
+
+ bond = kzalloc(sizeof(*bond), GFP_KERNEL);
+ if (!bond)
+ return ERR_PTR(-ENOMEM);
+
+ mutex_lock(&iommu_sva_lock);
+ /* Search for an existing domain. */
+ domain = iommu_get_domain_for_dev_pasid(dev, mm->pasid);
+ if (domain) {
This isn't safe, or sane. A driver could have attached something to
this PASID that is not a SVA domain and thus not protected by the
iommu_sva_lock.
At a minimum you should add a type match to
iommu_get_domain_for_dev_pasid(), eg to confirm it is a SVA domain and
do that check under the xa_lock of the pasid xarray.
And then the general idea is that SVA domain attach/detach must hold
this janky global lock.
Make sense. I will add this logic.
+ refcount_inc(&domain->users);
This atomic is always processed under the iommu_sva_lock, so it
doesn't need to be an atomic anymore.
Will change it to an integer.
Otherwise this design looks OK to me too
Thank you very much for your suggestions.
Best regards,
baolu
