Re: [PATCH net-next v2 6/6] enic: detect admin channel resources for SR-IOV

[Jakub Kicinski <kuba@kernel.org>]

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---
enic: detect admin channel resources for SR-IOV

This commit checks for the presence of admin channel BAR resources during
resource discovery and sets has_admin_channel when all four are available.
It also adds admin WQ, RQ, CQ and INTR fields to struct enic.

> diff --git a/drivers/net/ethernet/cisco/enic/enic.h b/drivers/net/ethernet/cisco/enic/enic.h
> index 67fd780b1fa1c..08472420f3a1f 100644
> --- a/drivers/net/ethernet/cisco/enic/enic.h
> +++ b/drivers/net/ethernet/cisco/enic/enic.h
> @@ -289,6 +289,13 @@ struct enic {
>  	u8 rss_key[ENIC_RSS_LEN];
>  	struct vnic_gen_stats gen_stats;
>  	enum ext_cq ext_cq;
> +
> +	/* Admin channel resources for SR-IOV MBOX */
> +	bool has_admin_channel;
> +	struct vnic_wq admin_wq;
> +	struct vnic_rq admin_rq;
> +	struct vnic_cq admin_cq[2];
> +	struct vnic_intr admin_intr;
>  };

[ ... ]

> diff --git a/drivers/net/ethernet/cisco/enic/enic_res.c b/drivers/net/ethernet/cisco/enic/enic_res.c
> index bbd3143ed73e7..5ca3e5aec7f93 100644
> --- a/drivers/net/ethernet/cisco/enic/enic_res.c
> +++ b/drivers/net/ethernet/cisco/enic/enic_res.c
> @@ -205,10 +205,17 @@ void enic_get_res_counts(struct enic *enic)
>  	enic->cq_count = enic->cq_avail;
>  	enic->intr_count = enic->intr_avail;
>  
> +	enic->has_admin_channel =
> +		vnic_dev_get_res_count(enic->vdev, RES_TYPE_ADMIN_WQ) >= 1 &&
> +		vnic_dev_get_res_count(enic->vdev, RES_TYPE_ADMIN_RQ) >= 1 &&
> +		vnic_dev_get_res_count(enic->vdev, RES_TYPE_ADMIN_CQ) >= 1 &&

Is it possible for the hardware to provide exactly 1 admin completion queue?

Because struct enic allocates two admin_cq entries:

    struct vnic_cq admin_cq[2];

If the firmware only provides one RES_TYPE_ADMIN_CQ, this check will pass,
but later initialization of admin_cq[1] might access memory past the end of
the validated memory-mapped I/O boundary.

Should this check be >= 2, or use ARRAY_SIZE(enic->admin_cq), to ensure
both queues are backed by hardware?

> +		vnic_dev_get_res_count(enic->vdev, RES_TYPE_SRIOV_INTR) >= 1;
> +