kernel.git/drivers/dma/idxd/init.c, branch linux-5.18.y

dmaengine: idxd: Remove useless DMA-32 fallback configuration

2022-03-11T09:53:36Z

As stated in [1], dma_set_mask() with a 64-bit mask never fails if dev->dma_mask is non-NULL. So, if it fails, the 32 bits case will also fail for the same reason. Simplify code and remove some dead code accordingly. [1]: https://lore.kernel.org/linux-kernel/YL3vSPK5DXTNvgdx@infradead.org/#t Signed-off-by: Christophe JAILLET Acked-by: Dave Jiang Link: https://lore.kernel.org/r/009c80294dba72858cd8a6ed2ed81041df1b1e82.1642231430.git.christophe.jaillet@wanadoo.fr Signed-off-by: Vinod Koul

dmaengine: idxd: change bandwidth token to read buffers

2022-01-05T07:44:25Z

DSA spec v1.2 has changed the term of "bandwidth tokens" to "read buffers" in order to make the concept clearer. Deprecate bandwidth token naming in the driver and convert to read buffers in order to match with the spec and reduce confusion when reading the spec. Signed-off-by: Dave Jiang Link: https://lore.kernel.org/r/163951338932.2988321.6162640806935567317.stgit@djiang5-desk3.ch.intel.com Signed-off-by: Vinod Koul

dmaengine: idxd: change MSIX allocation based on per wq activation

2022-01-05T07:41:22Z

Change the driver where WQ interrupt is requested only when wq is being enabled. This new scheme set things up so that request_threaded_irq() is only called when a kernel wq type is being enabled. This also sets up for future interrupt request where different interrupt handler such as wq occupancy interrupt can be setup instead of the wq completion interrupt. Not calling request_irq() until the WQ actually needs an irq also prevents wasting of CPU irq vectors on x86 systems, which is a limited resource. idxd_flush_pending_descs() is moved to device.c since descriptor flushing is now part of wq disable rather than shutdown(). Signed-off-by: Dave Jiang Link: https://lore.kernel.org/r/163942149487.2412839.6691222855803875848.stgit@djiang5-desk3.ch.intel.com Signed-off-by: Vinod Koul

dmaengine: idxd: fix descriptor flushing locking

2022-01-05T07:41:22Z

The descriptor flushing for shutdown is not holding the irq_entry list lock. If there's ongoing interrupt completion handling, this can corrupt the list. Add locking to protect list walking. Also refactor the code so it's more compact. Fixes: 8f47d1a5e545 ("dmaengine: idxd: connect idxd to dmaengine subsystem") Signed-off-by: Dave Jiang Link: https://lore.kernel.org/r/163942148935.2412839.18282664745572777280.stgit@djiang5-desk3.ch.intel.com Signed-off-by: Vinod Koul

dmaengine: idxd: embed irq_entry in idxd_wq struct

2022-01-05T07:41:21Z

With irq_entry already being associated with the wq in a 1:1 relationship, embed the irq_entry in the idxd_wq struct and remove back pointers for idxe_wq and idxd_device. In the process of this work, clean up the interrupt handle assignment so that there's no decision to be made during submit call on where interrupt handle value comes from. Set the interrupt handle during irq request initialization time. irq_entry 0 is designated as special and is tied to the device itself. Signed-off-by: Dave Jiang Link: https://lore.kernel.org/r/163942148362.2412839.12055447853311267866.stgit@djiang5-desk3.ch.intel.com Signed-off-by: Vinod Koul

dmaengine: idxd: add knob for enqcmds retries

2021-12-17T16:09:28Z

Add a sysfs knob to allow tuning of retries for the kernel ENQCMDS descriptor submission. While on host, it is not as likely that ENQCMDS return busy during normal operations due to the driver controlling the number of descriptors allocated for submission. However, when the driver is operating as a guest driver, the chance of retry goes up significantly due to sharing a wq with multiple VMs. A default value is provided with the system admin being able to tune the value on a per WQ basis. Suggested-by: Sanjay Kumar Signed-off-by: Dave Jiang Link: https://lore.kernel.org/r/163820629464.2702134.7577370098568297574.stgit@djiang5-desk3.ch.intel.com Signed-off-by: Vinod Koul

dmaengine: idxd: set defaults for wq configs

2021-12-17T16:09:28Z

Add default values for wq size, max_xfer_size and max_batch_size. These values should provide a general guidance for the wq configuration when the user does not specify any specific values. Signed-off-by: Dave Jiang Link: https://lore.kernel.org/r/163528473483.3926048.7950067926287180976.stgit@djiang5-desk3.ch.intel.com Signed-off-by: Vinod Koul

dmaengine: idxd: handle interrupt handle revoked event

2021-11-22T05:51:26Z

"Interrupt handle revoked" is an event that happens when the driver is running on a guest kernel and the VM is migrated to a new machine. The device will trigger an interrupt that signals to the guest driver that the interrupt handles need to be replaced. The misc irq thread function calls a helper function to handle the event. The function uses the WQ percpu_ref to quiesce the kernel submissions. It then replaces the interrupt handles by requesting interrupt handle command for each I/O MSIX vector. Once the handle is updated, the driver will unblock the submission path to allow new submissions. The submitter will attempt to acquire a percpu_ref before submission. When the request fails, it will wait on the wq_resurrect 'completion'. The driver does anticipate the possibility of descriptors being submitted before the WQ percpu_ref is killed. If a descriptor has already been submitted, it will return with incorrect interrupt handle status. The descriptor will be re-submitted with the new interrupt handle on the completion path. For descriptors with incorrect interrupt handles, completion interrupt won't be triggered. At the completion of the interrupt handle refresh, the handling function will call idxd_int_handle_refresh_drain() to issue drain descriptors to each of the wq with associated interrupt handle. The drain descriptor will have interrupt request set but without completion record. This will ensure all descriptors with incorrect interrupt completion handle get drained and a completion interrupt is triggered for the guest driver to process them. Reviewed-by: Kevin Tian Co-Developed-by: Sanjay Kumar Signed-off-by: Dave Jiang Link: https://lore.kernel.org/r/163528420189.3925689.18212568593220415551.stgit@djiang5-desk3.ch.intel.com Signed-off-by: Vinod Koul

dmaengine: idxd: int handle management refactoring

2021-11-22T05:51:26Z

Attach int_handle to irq_entry. This removes the separate management of int handles and reduces the confusion of interating through int handles that is off by 1 count. Reviewed-by: Kevin Tian Signed-off-by: Dave Jiang Link: https://lore.kernel.org/r/163528417065.3925689.11505755433684476288.stgit@djiang5-desk3.ch.intel.com Signed-off-by: Vinod Koul

dmaengine: idxd: rework descriptor free path on failure

2021-11-22T05:51:26Z

Refactor the completion function to allow skipping of descriptor freeing on the submission failure path. This completely removes descriptor freeing from the submit failure path and leave the responsibility to the caller. Reviewed-by: Kevin Tian Signed-off-by: Dave Jiang Link: https://lore.kernel.org/r/163528416222.3925689.12859769271667814762.stgit@djiang5-desk3.ch.intel.com Signed-off-by: Vinod Koul