> From: Lu Baolu <baolu...@linux.intel.com>
> Sent: Sunday, April 10, 2022 6:25 PM
> +struct iommu_sva *
> +iommu_sva_bind_device(struct device *dev, struct mm_struct *mm, void
> *drvdata)
> +{
> + int ret = -EINVAL;
> + struct iommu_sva *handle;
> + struct iommu_domain *domain;
> + struct iommu_sva_ioas *ioas;
> +
> + /*
> + * TODO: Remove the drvdata parameter after kernel PASID support
> is
> + * enabled for the idxd driver.
> + */
> + if (drvdata)
> + return ERR_PTR(-EOPNOTSUPP);
> +
> + /* Allocate mm->pasid if necessary. */
> + ret = iommu_sva_alloc_pasid(mm, 1, (1U << dev->iommu->pasid_bits)
> - 1);
> + if (ret)
> + return ERR_PTR(ret);
> +
> + mutex_lock(&iommu_sva_lock);
> + ioas = iommu_sva_ioas_get(mm, mm->pasid);
> + if (!ioas) {
> + ret = -ENOMEM;
ioas can be NULL for multiple reasons, e.g. :
1) ioas->mm != mm;
2) kzalloc failure;
3) xa_store failure;
It's more sensible to return error from iommu_sva_ioas_get() directly.
> + goto out_unlock;
> + }
> +
> + /* Search for an existing bond. */
> + list_for_each_entry(handle, &ioas->bonds, node) {
> + if (handle->dev == dev) {
> + refcount_inc(&handle->users);
> + /* No new bond, drop the counter. */
> + iommu_sva_ioas_put(ioas);
> + goto out_success;
> + }
> + }
> +
> + handle = kzalloc(sizeof(*handle), GFP_KERNEL);
s/handle/bond/?
> + if (!handle) {
> + ret = -ENOMEM;
> + goto out_put_ioas;
> + }
> +
> + /* The reference to ioas will be kept until domain free. */
> + domain = iommu_sva_alloc_domain(dev, ioas);
Shouldn't we first try whether existing domains are compatible to this
device?
> @@ -1952,6 +1954,7 @@ EXPORT_SYMBOL_GPL(iommu_domain_alloc);
> void iommu_domain_free(struct iommu_domain *domain)
> {
> iommu_put_dma_cookie(domain);
> + iommu_sva_ioas_put(domain->sva_ioas);
> domain->ops->free(domain);
> }
is it good to have general iommu_domain_free() to always call a put()
function for a specific domain type? Why cannot it be done before
calling iommu_domain_free() in sva-lib.c?
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