On 5/15/24 3:57 PM, Tian, Kevin wrote:
From: Baolu Lu <baolu.lu@xxxxxxxxxxxxxxx>
Sent: Wednesday, May 8, 2024 6:05 PM
On 2024/5/8 8:11, Jason Gunthorpe wrote:
On Tue, Apr 30, 2024 at 10:57:06PM +0800, Lu Baolu wrote:
diff --git a/drivers/iommu/iommu-priv.h b/drivers/iommu/iommu-priv.h
index ae65e0b85d69..1a0450a83bd0 100644
--- a/drivers/iommu/iommu-priv.h
+++ b/drivers/iommu/iommu-priv.h
@@ -36,6 +36,10 @@ struct iommu_attach_handle {
struct device *dev;
refcount_t users;
};
+ /* attach data for IOMMUFD */
+ struct {
+ void *idev;
+ };
We can use a proper type here, just forward declare it.
But this sequence in the other patch:
+ ret = iommu_attach_group(hwpt->domain, idev->igroup->group);
+ if (ret) {
+ iommufd_fault_iopf_disable(idev);
+ return ret;
+ }
+
+ handle = iommu_attach_handle_get(idev->igroup->group,
IOMMU_NO_PASID, 0);
+ handle->idev = idev;
Is why I was imagining the caller would allocate, because now we have
the issue that a fault capable domain was installed into the IOMMU
before it's handle could be fully setup, so we have a race where a
fault could come in right between those things. Then what happens?
I suppose we can retry the fault and by the time it comes back the
race should resolve. A bit ugly I suppose.
You are right. It makes more sense if the attached data is allocated and
managed by the caller. I will go in this direction and update my series.
I will also consider other review comments you have given in other
places.
Does this direction imply a new iommu_attach_group_handle() helper
to pass in the caller-allocated handle pointer or exposing a new
iommu_group_set_handle() to set the handle to the group pasid_array
and then having iomm_attach_group() to update the domain info in
the handle?
I will add new iommu_attach/replace/detach_group_handle() helpers. Like
below:
+/**
+ * iommu_attach_group_handle - Attach an IOMMU domain to an IOMMU group
+ * @domain: IOMMU domain to attach
+ * @group: IOMMU group that will be attached
+ * @handle: attach handle
+ *
+ * Returns 0 on success and error code on failure.
+ *
+ * This is a variant of iommu_attach_group(). It allows the caller to
provide
+ * an attach handle and use it when the domain is attached. This is
currently
+ * only designed for IOMMUFD to deliver the I/O page faults.
+ */
+int iommu_attach_group_handle(struct iommu_domain *domain,
+ struct iommu_group *group,
+ struct iommu_attach_handle *handle)
Best regards,
baolu
