Messages in this thread | | | Date | Wed, 11 May 2022 15:21:31 +0800 | Subject | Re: [PATCH v6 08/12] iommu/sva: Use attach/detach_pasid_dev in SVA interfaces | From | Baolu Lu <> |
| |
On 2022/5/10 23:23, Jason Gunthorpe wrote: > On Tue, May 10, 2022 at 02:17:34PM +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 >> + * @drvdata: opaque data pointer to pass to bind callback >> + * >> + * 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, void *drvdata) >> +{ >> + int ret = -EINVAL; >> + struct iommu_sva *handle; >> + struct iommu_domain *domain; >> + >> + /* >> + * TODO: Remove the drvdata parameter after kernel PASID support is >> + * enabled for the idxd driver. >> + */ >> + if (drvdata) >> + return ERR_PTR(-EOPNOTSUPP); > > Why is this being left behind? Clean up the callers too please.
Okay, let me try to.
> >> + /* 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); >> + /* Search for an existing bond. */ >> + handle = xa_load(&dev->iommu->sva_bonds, mm->pasid); >> + if (handle) { >> + refcount_inc(&handle->users); >> + goto out_success; >> + } > > How can there be an existing bond? > > dev->iommu is per-device > > The device_group_immutable_singleton() insists on a single device > group > > Basically 'sva_bonds' is the same thing as the group->pasid_array.
Yes, really.
> > Assuming we leave room for multi-device groups this logic should just > be > > group = iommu_group_get(dev); > if (!group) > return -ENODEV; > > mutex_lock(&group->mutex); > domain = xa_load(&group->pasid_array, mm->pasid); > if (!domain || domain->type != IOMMU_DOMAIN_SVA || domain->mm != mm) > domain = iommu_sva_alloc_domain(dev, mm); > > ?
Agreed. As a helper in iommu core, how about making it more generic like below?
+struct iommu_domain *iommu_get_domain_for_dev_pasid(struct device *dev, + iosid_t pasid, + unsigned int type) +{ + struct iommu_domain *domain; + struct iommu_group *group; + + if (!pasid_valid(pasid)) + return NULL; + + group = iommu_group_get(dev); + if (!group) + return NULL; + + mutex_lock(&group->mutex); + domain = xa_load(&group->pasid_array, pasid); + if (domain && domain->type != type) + domain = NULL; + mutex_unlock(&group->mutex); + iommu_group_put(group); + + return domain; +}
> > And stick the refcount in the sva_domain > > Also, given the current arrangement it might make sense to have a > struct iommu_domain_sva given that no driver is wrappering this in > something else.
Fair enough. How about below wrapper?
+struct iommu_sva_domain { + /* + * Common iommu domain header, *must* be put at the top + * of the structure. + */ + struct iommu_domain domain; + struct mm_struct *mm; + struct iommu_sva bond; +}
The refcount is wrapped in bond.
Best regards, baolu
| |