Re: [PATCH v2 04/10] dmaengine: idxd: Flush kernel workqueues on Function Level Reset

[Dave Jiang <dave.jiang@intel.com>]

On 8/21/25 3:59 PM, Vinicius Costa Gomes wrote:
> When a Function Level Reset (FLR) happens, terminate the pending
> descriptors that were issued by in-kernel users and disable the
> interrupts associated with those. They will be re-enabled after FLR
> finishes.
> 
> idxd_wq_flush_desc() is declared on idxd.h because it's going to be
> used in by the DMA backend in a future patch.
> 
> Signed-off-by: Vinicius Costa Gomes <vinicius.gomes@intel.com>
Reviewed-by: Dave Jiang <dave.jiang@intel.com>

> ---
>  drivers/dma/idxd/device.c | 20 ++++++++++++++++++++
>  drivers/dma/idxd/idxd.h   |  1 +
>  drivers/dma/idxd/irq.c    | 16 ++++++++++++++++
>  3 files changed, 37 insertions(+)
> 
> diff --git a/drivers/dma/idxd/device.c b/drivers/dma/idxd/device.c
> index 02bda8868e24..c62808e30417 100644
> --- a/drivers/dma/idxd/device.c
> +++ b/drivers/dma/idxd/device.c
> @@ -1319,6 +1319,11 @@ void idxd_wq_free_irq(struct idxd_wq *wq)
>  
>  	free_irq(ie->vector, ie);
>  	idxd_flush_pending_descs(ie);
> +
> +	/* The interrupt might have been already released by FLR */
> +	if (ie->int_handle == INVALID_INT_HANDLE)
> +		return;
> +
>  	if (idxd->request_int_handles)
>  		idxd_device_release_int_handle(idxd, ie->int_handle, IDXD_IRQ_MSIX);
>  	idxd_device_clear_perm_entry(idxd, ie);
> @@ -1327,6 +1332,21 @@ void idxd_wq_free_irq(struct idxd_wq *wq)
>  	ie->pasid = IOMMU_PASID_INVALID;
>  }
>  
> +void idxd_wq_flush_descs(struct idxd_wq *wq)
> +{
> +	struct idxd_irq_entry *ie = &wq->ie;
> +	struct idxd_device *idxd = wq->idxd;
> +
> +	if (wq->state != IDXD_WQ_ENABLED || wq->type != IDXD_WQT_KERNEL)
> +		return;
> +
> +	idxd_flush_pending_descs(ie);
> +	if (idxd->request_int_handles)
> +		idxd_device_release_int_handle(idxd, ie->int_handle, IDXD_IRQ_MSIX);
> +	idxd_device_clear_perm_entry(idxd, ie);
> +	ie->int_handle = INVALID_INT_HANDLE;
> +}
> +
>  int idxd_wq_request_irq(struct idxd_wq *wq)
>  {
>  	struct idxd_device *idxd = wq->idxd;
> diff --git a/drivers/dma/idxd/idxd.h b/drivers/dma/idxd/idxd.h
> index 74e6695881e6..fb7f570e002b 100644
> --- a/drivers/dma/idxd/idxd.h
> +++ b/drivers/dma/idxd/idxd.h
> @@ -784,6 +784,7 @@ void idxd_wq_quiesce(struct idxd_wq *wq);
>  int idxd_wq_init_percpu_ref(struct idxd_wq *wq);
>  void idxd_wq_free_irq(struct idxd_wq *wq);
>  int idxd_wq_request_irq(struct idxd_wq *wq);
> +void idxd_wq_flush_descs(struct idxd_wq *wq);
>  
>  /* submission */
>  int idxd_submit_desc(struct idxd_wq *wq, struct idxd_desc *desc);
> diff --git a/drivers/dma/idxd/irq.c b/drivers/dma/idxd/irq.c
> index 1107db3ce0a3..8d0eaf5029fa 100644
> --- a/drivers/dma/idxd/irq.c
> +++ b/drivers/dma/idxd/irq.c
> @@ -397,6 +397,17 @@ static void idxd_device_flr(struct work_struct *work)
>  		dev_err(&idxd->pdev->dev, "FLR failed\n");
>  }
>  
> +static void idxd_wqs_flush_descs(struct idxd_device *idxd)
> +{
> +	int i;
> +
> +	for (i = 0; i < idxd->max_wqs; i++) {
> +		struct idxd_wq *wq = idxd->wqs[i];
> +
> +		idxd_wq_flush_descs(wq);
> +	}
> +}
> +
>  static irqreturn_t idxd_halt(struct idxd_device *idxd)
>  {
>  	union gensts_reg gensts;
> @@ -415,6 +426,11 @@ static irqreturn_t idxd_halt(struct idxd_device *idxd)
>  		} else if (gensts.reset_type == IDXD_DEVICE_RESET_FLR) {
>  			idxd->state = IDXD_DEV_HALTED;
>  			idxd_mask_error_interrupts(idxd);
> +			/* Flush all pending descriptors, and disable
> +			 * interrupts, they will be re-enabled when FLR
> +			 * concludes.
> +			 */
> +			idxd_wqs_flush_descs(idxd);
>  			dev_dbg(&idxd->pdev->dev,
>  				"idxd halted, doing FLR. After FLR, configs are restored\n");
>  			INIT_WORK(&idxd->work, idxd_device_flr);
>