RE: [PATCH v3] vdpa/ifc/base: wait for queue disable before saving q-state

["Xia, Chenbo" <chenbo.xia@intel.com>]

> -----Original Message-----
> From: Maheshwari, Abhishek <abhishek.maheshwari@intel.com>
> Sent: Wednesday, November 2, 2022 5:55 PM
> To: maxime.coquelin@redhat.com; Wang, Xiao W <xiao.w.wang@intel.com>
> Cc: dev@dpdk.org; stable@dpdk.org; Xia, Chenbo <chenbo.xia@intel.com>;
> Mandal, Purna Chandra <purna.chandra.mandal@intel.com>; Pei, Andy
> <andy.pei@intel.com>; Maheshwari, Abhishek <abhishek.maheshwari@intel.com>
> Subject: [PATCH v3] vdpa/ifc/base: wait for queue disable before saving q-
> state
> 
> Some ifc hardware require synchronization between disabling a queue and
> saving queue-state from LM registers. When queue is disabled from vDPA
> driver, ifc device stops executing new virtio-cmds and then updates LM
> registers with used/avail index. Before saving the queue-state, vDPA
> driver should wait until the queue is disabled from backend.
> 
> Fixes: 5d75517beffe ("vdpa/ifc/base: access block device registers")
> Cc: andy.pei@intel.com

No need to add above next time

> Cc: stable@dpdk.org
> 
> Signed-off-by: Abhishek Maheshwari <abhishek.maheshwari@intel.com>
> 
> ---
> v2:
> * Fixing the styling issues
> * Addressing comment to avoid reading the register again after
>   exhausting the tries
> 
> v3:
> * Fixing warning condition
> ---
>  drivers/vdpa/ifc/base/ifcvf.c | 16 ++++++++++++++++
>  1 file changed, 16 insertions(+)
> 
> diff --git a/drivers/vdpa/ifc/base/ifcvf.c b/drivers/vdpa/ifc/base/ifcvf.c
> index f1e1474447..06996fd5d7 100644
> --- a/drivers/vdpa/ifc/base/ifcvf.c
> +++ b/drivers/vdpa/ifc/base/ifcvf.c
> @@ -257,6 +257,7 @@ ifcvf_hw_disable(struct ifcvf_hw *hw)
>  	u32 i;
>  	struct ifcvf_pci_common_cfg *cfg;
>  	u32 ring_state;
> +	int q_disable_try;
> 
>  	cfg = hw->common_cfg;
>  	if (!cfg) {
> @@ -275,6 +276,21 @@ ifcvf_hw_disable(struct ifcvf_hw *hw)
>  			continue;
>  		}
> 
> +		/* Some ifc hardware require synchronization between disabling
> a
> +		 * queue and saving queue-state from LM registers. When queue
> is
> +		 * disabled from vDPA driver, ifc device stops executing new
> +		 * virtio-cmds and then updates LM registers with used/avail
> +		 * index. Before saving the queue-state, vDPA driver waits
> until
> +		 * the queue is disabled from backend.
> +		 */
> +		q_disable_try = 10;
> +		while (q_disable_try-- && IFCVF_READ_REG16(&cfg->queue_enable))
> +			msec_delay(10);
> +
> +		if (!q_disable_try)
> +			WARNINGOUT("Failed Q:%d disable, Saved state invalid\n",
> +				   i);

No need to start a new line here.

Thanks,
Chenbo

> +
>  		if (hw->device_type == IFCVF_BLK)
>  			ring_state = *(u32 *)(hw->lm_cfg +
>  					IFCVF_LM_RING_STATE_OFFSET +
> --
> 2.31.1