On 2024/2/8 1:59, Vasant Hegde wrote:
Hi Baolu,
On 2/7/2024 5:59 PM, Baolu Lu wrote:
On 2024/2/7 10:50, Tian, Kevin wrote:
From: Lu Baolu<baolu.lu@xxxxxxxxxxxxxxx>
Sent: Wednesday, February 7, 2024 9:33 AM
Convert iopf_queue_remove_device() to return void instead of an error code,
as the return value is never used. This removal helper is designed to be
never-failed, so there's no need for error handling.
Ack all outstanding page requests from the device with the response code of
IOMMU_PAGE_RESP_INVALID, indicating device should not attempt any retry.
Add comments to this helper explaining the steps involved in removing a
device from the iopf queue and disabling its PRI. The individual drivers
are expected to be adjusted accordingly. Here we just define the expected
behaviors of the individual iommu driver from the core's perspective.
Suggested-by: Jason Gunthorpe<jgg@xxxxxxxxxx>
Signed-off-by: Lu Baolu<baolu.lu@xxxxxxxxxxxxxxx>
Reviewed-by: Jason Gunthorpe<jgg@xxxxxxxxxx>
Tested-by: Yan Zhao<yan.y.zhao@xxxxxxxxx>
Reviewed-by: Kevin Tian<kevin.tian@xxxxxxxxx>, with one nit:
+ * Removing a device from an iopf_queue. It's recommended to follow
these
+ * steps when removing a device:
*
- * Return: 0 on success and <0 on error.
+ * - Disable new PRI reception: Turn off PRI generation in the IOMMU
hardware
+ * and flush any hardware page request queues. This should be done
before
+ * calling into this helper.
+ * - Acknowledge all outstanding PRQs to the device: Respond to all
outstanding
+ * page requests with IOMMU_PAGE_RESP_INVALID, indicating the device
should
+ * not retry. This helper function handles this.
this implies calling iopf_queue_remove_device() here.
+ * - Disable PRI on the device: After calling this helper, the caller could
+ * then disable PRI on the device.
+ * - Call iopf_queue_remove_device(): Calling iopf_queue_remove_device()
+ * essentially disassociates the device. The fault_param might still exist,
+ * but iommu_page_response() will do nothing. The device fault parameter
+ * reference count has been properly passed from
iommu_report_device_fault()
+ * to the fault handling work, and will eventually be released after
+ * iommu_page_response().
*/
but here it suggests calling iopf_queue_remove_device() again. If the comment
is just about to detail the behavior with that invocation shouldn't it be merged
with the previous one instead of pretending to be the final step for driver
to call?
Above just explains the behavior of calling iopf_queue_remove_device().
Can you please leave a line -OR- move this to previous para? Otherwise we will
get confused.
Sure. I will make it look like below.
/**
* iopf_queue_remove_device - Remove producer from fault queue
* @queue: IOPF queue
* @dev: device to remove
*
* Removing a device from an iopf_queue. It's recommended to follow these
* steps when removing a device:
*
* - Disable new PRI reception: Turn off PRI generation in the IOMMU
hardware
* and flush any hardware page request queues. This should be done before
* calling into this helper.
* - Acknowledge all outstanding PRQs to the device: Respond to all
outstanding
* page requests with IOMMU_PAGE_RESP_INVALID, indicating the device
should
* not retry. This helper function handles this.
* - Disable PRI on the device: After calling this helper, the caller could
* then disable PRI on the device.
*
* Calling iopf_queue_remove_device() essentially disassociates the device.
* The fault_param might still exist, but iommu_page_response() will do
* nothing. The device fault parameter reference count has been properly
* passed from iommu_report_device_fault() to the fault handling work, and
* will eventually be released after iommu_page_response().
*/
Best regards,
baolu
