Unverified Commit 6aaa8434 authored by Arnd Bergmann's avatar Arnd Bergmann
Browse files

Merge tag 'scmi-fixes-5.15' of... 

Merge tag 'scmi-fixes-5.15' of git://git.kernel.org/pub/scm/linux/kernel/git/sudeep.holla/linux into arm/fixes

SCMI fixes for v5.15

A few fixes addressing:
- Kconfig dependency between VIRTIO and ARM_SCMI_PROTOCOL
- Link-time error with __exit annotation for virtio_scmi_exit
- Unnecessary nested irqsave/irqrestore spinlocks in virtio transport
- Missing SMP barriers to protect accesses to SCMI virtio device

* tag 'scmi-fixes-5.15' of git://git.kernel.org/pub/scm/linux/kernel/git/sudeep.holla/linux:
  firmware: arm_scmi: Add proper barriers to scmi virtio device
  firmware: arm_scmi: Simplify spinlocks in virtio transport
  firmware: arm_scmi: Remove __exit annotation
  firmware: arm_scmi: Fix virtio transport Kconfig dependency

Link: https://lore.kernel.org/r/20211007102822.27886-1-sudeep.holla@arm.com


Signed-off-by: default avatarArnd Bergmann <arnd@arndb.de>
parents 3c7f58b3 bf1acf80

drivers/firmware/arm_scmi/Kconfig

+1 −1
Original line number Diff line number Diff line
@@ -68,7 +68,7 @@ config ARM_SCMI_TRANSPORT_SMC 


config ARM_SCMI_TRANSPORT_VIRTIO

	bool "SCMI transport based on VirtIO"

	depends on VIRTIO

	depends on VIRTIO=y || VIRTIO=ARM_SCMI_PROTOCOL

	select ARM_SCMI_HAVE_TRANSPORT

	select ARM_SCMI_HAVE_MSG

	help

drivers/firmware/arm_scmi/virtio.c

+31 −13
Original line number Diff line number Diff line
@@ -110,18 +110,16 @@ static void scmi_finalize_message(struct scmi_vio_channel *vioch, 
	if (vioch->is_rx) {

		scmi_vio_feed_vq_rx(vioch, msg);

	} else {

		unsigned long flags;



		spin_lock_irqsave(&vioch->lock, flags);

		/* Here IRQs are assumed to be already disabled by the caller */

		spin_lock(&vioch->lock);

		list_add(&msg->list, &vioch->free_list);

		spin_unlock_irqrestore(&vioch->lock, flags);

		spin_unlock(&vioch->lock);

	}

}



static void scmi_vio_complete_cb(struct virtqueue *vqueue)

{

	unsigned long ready_flags;

	unsigned long flags;

	unsigned int length;

	struct scmi_vio_channel *vioch;

	struct scmi_vio_msg *msg;
@@ -140,7 +138,8 @@ static void scmi_vio_complete_cb(struct virtqueue *vqueue) 
			goto unlock_ready_out;

		}



		spin_lock_irqsave(&vioch->lock, flags);

		/* IRQs already disabled here no need to irqsave */

		spin_lock(&vioch->lock);

		if (cb_enabled) {

			virtqueue_disable_cb(vqueue);

			cb_enabled = false;
@@ -151,7 +150,7 @@ static void scmi_vio_complete_cb(struct virtqueue *vqueue) 
				goto unlock_out;

			cb_enabled = true;

		}

		spin_unlock_irqrestore(&vioch->lock, flags);

		spin_unlock(&vioch->lock);



		if (msg) {

			msg->rx_len = length;
@@ -161,11 +160,18 @@ static void scmi_vio_complete_cb(struct virtqueue *vqueue) 
			scmi_finalize_message(vioch, msg);

		}



		/*

		 * Release ready_lock and re-enable IRQs between loop iterations

		 * to allow virtio_chan_free() to possibly kick in and set the

		 * flag vioch->ready to false even in between processing of

		 * messages, so as to force outstanding messages to be ignored

		 * when system is shutting down.

		 */

		spin_unlock_irqrestore(&vioch->ready_lock, ready_flags);

	}



unlock_out:

	spin_unlock_irqrestore(&vioch->lock, flags);

	spin_unlock(&vioch->lock);

unlock_ready_out:

	spin_unlock_irqrestore(&vioch->ready_lock, ready_flags);

}
@@ -384,8 +390,11 @@ static int scmi_vio_probe(struct virtio_device *vdev) 
	struct virtqueue *vqs[VIRTIO_SCMI_VQ_MAX_CNT];



	/* Only one SCMI VirtiO device allowed */

	if (scmi_vdev)

		return -EINVAL;

	if (scmi_vdev) {

		dev_err(dev,

			"One SCMI Virtio device was already initialized: only one allowed.\n");

		return -EBUSY;

	}



	have_vq_rx = scmi_vio_have_vq_rx(vdev);

	vq_cnt = have_vq_rx ? VIRTIO_SCMI_VQ_MAX_CNT : 1;
@@ -428,16 +437,25 @@ static int scmi_vio_probe(struct virtio_device *vdev) 
	}



	vdev->priv = channels;

	scmi_vdev = vdev;

	/* Ensure initialized scmi_vdev is visible */

	smp_store_mb(scmi_vdev, vdev);



	return 0;

}



static void scmi_vio_remove(struct virtio_device *vdev)

{

	/*

	 * Once we get here, virtio_chan_free() will have already been called by

	 * the SCMI core for any existing channel and, as a consequence, all the

	 * virtio channels will have been already marked NOT ready, causing any

	 * outstanding message on any vqueue to be ignored by complete_cb: now

	 * we can just stop processing buffers and destroy the vqueues.

	 */

	vdev->config->reset(vdev);

	vdev->config->del_vqs(vdev);

	scmi_vdev = NULL;

	/* Ensure scmi_vdev is visible as NULL */

	smp_store_mb(scmi_vdev, NULL);

}



static int scmi_vio_validate(struct virtio_device *vdev)
@@ -476,7 +494,7 @@ static int __init virtio_scmi_init(void) 
	return register_virtio_driver(&virtio_scmi_driver);

}



static void __exit virtio_scmi_exit(void)

static void virtio_scmi_exit(void)

{

	unregister_virtio_driver(&virtio_scmi_driver);

}