linux-kernel - Re: [PATCH v3 07/17] firmware: arm_ffa: Implement the NOTIFICATION_INFO

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Message-ID: <20231004091021.GA1091193@rayden>
Date:   Wed, 4 Oct 2023 11:10:21 +0200
From:   Jens Wiklander <jens.wiklander@...aro.org>
To:     Sudeep Holla <sudeep.holla@....com>
Cc:     linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        Marc Bonnici <marc.bonnici@....com>,
        Coboy Chen <coboy.chen@...iatek.com>,
        Lorenzo Pieralisi <lpieralisi@...nel.org>,
        Olivier Deprez <olivier.deprez@....com>
Subject: Re: [PATCH v3 07/17] firmware: arm_ffa: Implement the
 NOTIFICATION_INFO_GET interface

On Fri, Sep 29, 2023 at 04:02:56PM +0100, Sudeep Holla wrote:
> The receiver’s scheduler uses the FFA_NOTIFICATION_INFO_GET interface
> to retrieve the list of endpoints that have pending notifications and
> must be run. A notification could be signaled by a sender in the secure
> world to a VM. The Hypervisor needs to determine which VM and vCPU
> (in case a per-vCPU notification is signaled) has a pending notification
> in this scenario. It must obtain this information through an invocation
> of the FFA_NOTIFICATION_INFO_GET.
> 
> Add the implementation of the NOTIFICATION_INFO_GET interface
> and prepare to use this to handle the schedule receiver interrupt.
> Implementation of handling notifications will be added later.
> 
> Signed-off-by: Sudeep Holla <sudeep.holla@....com>
> ---
>  drivers/firmware/arm_ffa/driver.c | 70 +++++++++++++++++++++++++++++++++++++++
>  1 file changed, 70 insertions(+)
> 
> diff --git a/drivers/firmware/arm_ffa/driver.c b/drivers/firmware/arm_ffa/driver.c
> index 02eedb7bc171..dfeeb751bebe 100644
> --- a/drivers/firmware/arm_ffa/driver.c
> +++ b/drivers/firmware/arm_ffa/driver.c
> @@ -602,6 +602,13 @@ static int ffa_notification_bitmap_destroy(void)
>  	(FIELD_PREP(RECEIVER_VCPU_MASK, (vcpu_r)) | \
>  	 FIELD_PREP(RECEIVER_ID_MASK, (r)))
>  
> +#define NOTIFICATION_INFO_GET_MORE_PEND_MASK	BIT(0)
> +#define NOTIFICATION_INFO_GET_ID_COUNT		GENMASK(11, 7)
> +#define ID_LIST_MASK_64				GENMASK(51, 12)
> +#define ID_LIST_MASK_32				GENMASK(31, 12)
> +#define MAX_IDS_64				20
> +#define MAX_IDS_32				10
> +
>  static int ffa_notification_bind_common(u16 dst_id, u64 bitmap,
>  					u32 flags, bool is_bind)
>  {
> @@ -673,6 +680,69 @@ static int ffa_notification_get(u32 flags, struct ffa_notify_bitmaps *notify)
>  	return 0;
>  }
>  
> +static void __do_sched_recv_cb(u16 partition_id, u16 vcpu, bool is_per_vcpu)
> +{
> +	pr_err("Callback for partition 0x%x failed.\n", partition_id);
> +}
> +
> +static void ffa_notification_info_get(bool is_64b)
> +{
> +	int idx, list, max_ids, lists_cnt, ids_processed, ids_count[MAX_IDS_64];
> +	ffa_value_t ret;
> +	u64 id_list;
> +
> +	do {
> +		invoke_ffa_fn((ffa_value_t){
> +			  .a0 = FFA_FN_NATIVE(NOTIFICATION_INFO_GET),
> +			  }, &ret);
> +
> +		if (ret.a0 != FFA_FN_NATIVE(SUCCESS)) {

The specification doesn't require a response using 64-bit SMCCC, it is
valid to respond using 32-bit SMCCC too.

Thanks,
Jens

> +			if (ret.a2 != FFA_RET_NO_DATA)
> +				pr_err("Notification Info fetch failed: 0x%lx (0x%lx)",
> +				       ret.a0, ret.a2);
> +			return;
> +		}
> +
> +		ids_processed = 0;
> +		lists_cnt = FIELD_GET(NOTIFICATION_INFO_GET_ID_COUNT, ret.a2);
> +		if (is_64b) {
> +			max_ids = MAX_IDS_64;
> +			id_list = FIELD_GET(ID_LIST_MASK_64, ret.a2);
> +		} else {
> +			max_ids = MAX_IDS_32;
> +			id_list = FIELD_GET(ID_LIST_MASK_32, ret.a2);
> +		}
> +
> +		for (idx = 0; idx < lists_cnt; idx++, id_list >>= 2)
> +			ids_count[idx] = (id_list & 0x3) + 1;
> +
> +		/* Process IDs */
> +		for (list = 0; list < lists_cnt; list++) {
> +			u16 vcpu_id, part_id, *packed_id_list = (u16 *)&ret.a3;
> +
> +			if (ids_processed >= max_ids - 1)
> +				break;
> +
> +			part_id = packed_id_list[++ids_processed];
> +
> +			if (!ids_count[list]) { /* Global Notification */
> +				__do_sched_recv_cb(part_id, 0, false);
> +				continue;
> +			}
> +
> +			/* Per vCPU Notification */
> +			for (idx = 0; idx < ids_count[list]; idx++) {
> +				if (ids_processed >= max_ids - 1)
> +					break;
> +
> +				vcpu_id = packed_id_list[++ids_processed];
> +
> +				__do_sched_recv_cb(part_id, vcpu_id, true);
> +			}
> +		}
> +	} while (ret.a2 & NOTIFICATION_INFO_GET_MORE_PEND_MASK);
> +}
> +
>  static int ffa_run(struct ffa_device *dev, u16 vcpu)
>  {
>  	ffa_value_t ret;
> 
> -- 
> 2.42.0
>