> -----Original Message-----
> From: Maheshwari, Abhishek <[email protected]>
> Sent: Wednesday, November 2, 2022 5:55 PM
> To: [email protected]; Wang, Xiao W <[email protected]>
> Cc: [email protected]; [email protected]; Xia, Chenbo <[email protected]>;
> Mandal, Purna Chandra <[email protected]>; Pei, Andy
> <[email protected]>; Maheshwari, Abhishek
> <[email protected]>
> 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: [email protected]
> Cc: [email protected]
>
> Signed-off-by: Abhishek Maheshwari <[email protected]>
>
> ---
> 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);
> +
> if (hw->device_type == IFCVF_BLK)
> ring_state = *(u32 *)(hw->lm_cfg +
> IFCVF_LM_RING_STATE_OFFSET +
> --
> 2.31.1
Acked-by: Andy Pei <[email protected]>
