16 Jan
2024
16 Jan
'24
1:18 a.m.
From: Jason Gunthorpe jgg@nvidia.com Sent: Tuesday, January 16, 2024 1:25 AM
On Sun, Nov 26, 2023 at 10:34:23PM -0800, Yi Liu wrote:
+/**
- iommufd_device_pasid_detach - Disconnect a {device, pasid} to an
iommu_domain
- @idev: device to detach
- @pasid: pasid to detach
- Undo iommufd_device_pasid_attach(). This disconnects the idev/pasid
from
- the previously attached pt_id.
- */
+void iommufd_device_pasid_detach(struct iommufd_device *idev, u32
pasid)
+{
- struct iommufd_hw_pagetable *hwpt;
- hwpt = xa_load(&idev->pasid_hwpts, pasid);
- if (!hwpt)
return;- xa_erase(&idev->pasid_hwpts, pasid);
- iommu_detach_device_pasid(hwpt->domain, idev->dev, pasid);
- iommufd_hw_pagetable_put(idev->ictx, hwpt);
+}
None of this xarray stuff looks locked properly
I had an impression from past discussions that the caller should not race attach/detach/replace on same device or pasid, otherwise it is already a problem in a higher level.
and the original intention of the group lock was to ensure all devices in the group have a same view. Not exactly to guard concurrent attach/detach.
If this understanding is incorrect we can add a lock for sure. 😊