| Message ID | 20240328122958.83332-2-yi.l.liu@intel.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | Two enhancements to iommu_at[de]tach_device_pasid() | expand |
On 3/28/24 8:29 PM, Yi Liu wrote: > There is no error handling now in __iommu_set_group_pasid(), it relies on > its caller to loop all the devices to undo the pasid attachment. This is > not self-contained and has drawbacks. It would result in unnecessary > remove_dev_pasid() calls on the devices that have not been attached to the > new domain. But the remove_dev_pasid() callback would get the new domain > from the group->pasid_array. So for such devices, the iommu driver won't > find the attachment under the domain, hence unable to do cleanup. This may > not be a real problem today. But it depends on the implementation of the > underlying iommu driver. e.g. the intel iommu driver would warn for such > devices. Such warnings are unnecessary. > > To solve the above problem, it is necessary to handle the error within > __iommu_set_group_pasid(). It only loops the devices that have attached > to the new domain, and undo it. > > Fixes: 16603704559c ("iommu: Add attach/detach_dev_pasid iommu interfaces") > Suggested-by: Jason Gunthorpe<jgg@nvidia.com> > Reviewed-by: Jason Gunthorpe<jgg@nvidia.com> > Reviewed-by: Kevin Tian<kevin.tian@intel.com> > Signed-off-by: Yi Liu<yi.l.liu@intel.com> Reviewed-by: Lu Baolu <baolu.lu@linux.intel.com> Best regards, baolu
diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c index 098869007c69..bb3244df525e 100644 --- a/drivers/iommu/iommu.c +++ b/drivers/iommu/iommu.c @@ -3317,15 +3317,26 @@ EXPORT_SYMBOL_GPL(iommu_group_dma_owner_claimed); static int __iommu_set_group_pasid(struct iommu_domain *domain, struct iommu_group *group, ioasid_t pasid) { - struct group_device *device; - int ret = 0; + struct group_device *device, *last_gdev; + int ret; for_each_group_device(group, device) { ret = domain->ops->set_dev_pasid(domain, device->dev, pasid); if (ret) - break; + goto err_revert; } + return 0; + +err_revert: + last_gdev = device; + for_each_group_device(group, device) { + const struct iommu_ops *ops = dev_iommu_ops(device->dev); + + if (device == last_gdev) + break; + ops->remove_dev_pasid(device->dev, pasid); + } return ret; } @@ -3374,10 +3385,8 @@ int iommu_attach_device_pasid(struct iommu_domain *domain, } ret = __iommu_set_group_pasid(domain, group, pasid); - if (ret) { - __iommu_remove_group_pasid(group, pasid); + if (ret) xa_erase(&group->pasid_array, pasid); - } out_unlock: mutex_unlock(&group->mutex); return ret;
There is no error handling now in __iommu_set_group_pasid(), it relies on its caller to loop all the devices to undo the pasid attachment. This is not self-contained and has drawbacks. It would result in unnecessary remove_dev_pasid() calls on the devices that have not been attached to the new domain. But the remove_dev_pasid() callback would get the new domain from the group->pasid_array. So for such devices, the iommu driver won't find the attachment under the domain, hence unable to do cleanup. This may not be a real problem today. But it depends on the implementation of the underlying iommu driver. e.g. the intel iommu driver would warn for such devices. Such warnings are unnecessary. To solve the above problem, it is necessary to handle the error within __iommu_set_group_pasid(). It only loops the devices that have attached to the new domain, and undo it. Fixes: 16603704559c ("iommu: Add attach/detach_dev_pasid iommu interfaces") Suggested-by: Jason Gunthorpe <jgg@nvidia.com> Reviewed-by: Jason Gunthorpe <jgg@nvidia.com> Reviewed-by: Kevin Tian <kevin.tian@intel.com> Signed-off-by: Yi Liu <yi.l.liu@intel.com> --- drivers/iommu/iommu.c | 21 +++++++++++++++------ 1 file changed, 15 insertions(+), 6 deletions(-)