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Commit 96b14536 authored by Cornelia Huck's avatar Cornelia Huck Committed by Christian Borntraeger
Browse files

virtio-ccw: virtio-ccw adapter interrupt support. 



Implement the new CCW_CMD_SET_IND_ADAPTER command and try to enable
adapter interrupts for every device on the first startup. If the host
does not support adapter interrupts, fall back to normal I/O interrupts.

virtio-ccw adapter interrupts use the same isc as normal I/O subchannels
and share a summary indicator for all devices sharing the same indicator
area.

Indicator bits for the individual virtqueues may be contained in the same
indicator area for different devices.

Signed-off-by: default avatarCornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: default avatarChristian Borntraeger <borntraeger@de.ibm.com>
parent 84ec96a6

arch/s390/include/asm/irq.h

+1 −0
Original line number Diff line number Diff line
@@ -53,6 +53,7 @@ enum interruption_class { 
	IRQIO_PCI,

	IRQIO_MSI,

	IRQIO_VIR,

	IRQIO_VAI,

	NMI_NMI,

	CPU_RST,

	NR_ARCH_IRQS

arch/s390/kernel/irq.c

+1 −0
Original line number Diff line number Diff line
@@ -84,6 +84,7 @@ static const struct irq_class irqclass_sub_desc[NR_ARCH_IRQS] = { 
	[IRQIO_PCI]  = {.name = "PCI", .desc = "[I/O] PCI Interrupt" },

	[IRQIO_MSI]  = {.name = "MSI", .desc = "[I/O] MSI Interrupt" },

	[IRQIO_VIR]  = {.name = "VIR", .desc = "[I/O] Virtual I/O Devices"},

	[IRQIO_VAI]  = {.name = "VAI", .desc = "[I/O] Virtual I/O Devices AI"},

	[NMI_NMI]    = {.name = "NMI", .desc = "[NMI] Machine Check"},

	[CPU_RST]    = {.name = "RST", .desc = "[CPU] CPU Restart"},

};

drivers/s390/kvm/virtio_ccw.c

+268 −10
Original line number Diff line number Diff line 
/*

 * ccw based virtio transport

 *

 * Copyright IBM Corp. 2012

 * Copyright IBM Corp. 2012, 2014

 *

 * This program is free software; you can redistribute it and/or modify

 * it under the terms of the GNU General Public License (version 2 only)
@@ -32,6 +32,8 @@ 
#include <asm/cio.h>

#include <asm/ccwdev.h>

#include <asm/virtio-ccw.h>

#include <asm/isc.h>

#include <asm/airq.h>



/*

 * virtio related functions
@@ -58,6 +60,8 @@ struct virtio_ccw_device { 
	unsigned long indicators;

	unsigned long indicators2;

	struct vq_config_block *config_block;

	bool is_thinint;

	void *airq_info;

};



struct vq_info_block {
@@ -72,15 +76,38 @@ struct virtio_feature_desc { 
	__u8 index;

} __packed;



struct virtio_thinint_area {

	unsigned long summary_indicator;

	unsigned long indicator;

	u64 bit_nr;

	u8 isc;

} __packed;



struct virtio_ccw_vq_info {

	struct virtqueue *vq;

	int num;

	void *queue;

	struct vq_info_block *info_block;

	int bit_nr;

	struct list_head node;

	long cookie;

};



#define VIRTIO_AIRQ_ISC IO_SCH_ISC /* inherit from subchannel */



#define VIRTIO_IV_BITS (L1_CACHE_BYTES * 8)

#define MAX_AIRQ_AREAS 20



static int virtio_ccw_use_airq = 1;



struct airq_info {

	rwlock_t lock;

	u8 summary_indicator;

	struct airq_struct airq;

	struct airq_iv *aiv;

};

static struct airq_info *airq_areas[MAX_AIRQ_AREAS];



#define CCW_CMD_SET_VQ 0x13

#define CCW_CMD_VDEV_RESET 0x33

#define CCW_CMD_SET_IND 0x43
@@ -91,6 +118,7 @@ struct virtio_ccw_vq_info { 
#define CCW_CMD_WRITE_CONF 0x21

#define CCW_CMD_WRITE_STATUS 0x31

#define CCW_CMD_READ_VQ_CONF 0x32

#define CCW_CMD_SET_IND_ADAPTER 0x73



#define VIRTIO_CCW_DOING_SET_VQ 0x00010000

#define VIRTIO_CCW_DOING_RESET 0x00040000
@@ -102,6 +130,7 @@ struct virtio_ccw_vq_info { 
#define VIRTIO_CCW_DOING_SET_IND 0x01000000

#define VIRTIO_CCW_DOING_READ_VQ_CONF 0x02000000

#define VIRTIO_CCW_DOING_SET_CONF_IND 0x04000000

#define VIRTIO_CCW_DOING_SET_IND_ADAPTER 0x08000000

#define VIRTIO_CCW_INTPARM_MASK 0xffff0000



static struct virtio_ccw_device *to_vc_device(struct virtio_device *vdev)
@@ -109,6 +138,125 @@ static struct virtio_ccw_device *to_vc_device(struct virtio_device *vdev) 
	return container_of(vdev, struct virtio_ccw_device, vdev);

}



static void drop_airq_indicator(struct virtqueue *vq, struct airq_info *info)

{

	unsigned long i, flags;



	write_lock_irqsave(&info->lock, flags);

	for (i = 0; i < airq_iv_end(info->aiv); i++) {

		if (vq == (void *)airq_iv_get_ptr(info->aiv, i)) {

			airq_iv_free_bit(info->aiv, i);

			airq_iv_set_ptr(info->aiv, i, 0);

			break;

		}

	}

	write_unlock_irqrestore(&info->lock, flags);

}



static void virtio_airq_handler(struct airq_struct *airq)

{

	struct airq_info *info = container_of(airq, struct airq_info, airq);

	unsigned long ai;



	inc_irq_stat(IRQIO_VAI);

	read_lock(&info->lock);

	/* Walk through indicators field, summary indicator active. */

	for (ai = 0;;) {

		ai = airq_iv_scan(info->aiv, ai, airq_iv_end(info->aiv));

		if (ai == -1UL)

			break;

		vring_interrupt(0, (void *)airq_iv_get_ptr(info->aiv, ai));

	}

	info->summary_indicator = 0;

	smp_wmb();

	/* Walk through indicators field, summary indicator not active. */

	for (ai = 0;;) {

		ai = airq_iv_scan(info->aiv, ai, airq_iv_end(info->aiv));

		if (ai == -1UL)

			break;

		vring_interrupt(0, (void *)airq_iv_get_ptr(info->aiv, ai));

	}

	read_unlock(&info->lock);

}



static struct airq_info *new_airq_info(void)

{

	struct airq_info *info;

	int rc;



	info = kzalloc(sizeof(*info), GFP_KERNEL);

	if (!info)

		return NULL;

	rwlock_init(&info->lock);

	info->aiv = airq_iv_create(VIRTIO_IV_BITS, AIRQ_IV_ALLOC | AIRQ_IV_PTR);

	if (!info->aiv) {

		kfree(info);

		return NULL;

	}

	info->airq.handler = virtio_airq_handler;

	info->airq.lsi_ptr = &info->summary_indicator;

	info->airq.lsi_mask = 0xff;

	info->airq.isc = VIRTIO_AIRQ_ISC;

	rc = register_adapter_interrupt(&info->airq);

	if (rc) {

		airq_iv_release(info->aiv);

		kfree(info);

		return NULL;

	}

	return info;

}



static void destroy_airq_info(struct airq_info *info)

{

	if (!info)

		return;



	unregister_adapter_interrupt(&info->airq);

	airq_iv_release(info->aiv);

	kfree(info);

}



static unsigned long get_airq_indicator(struct virtqueue *vqs[], int nvqs,

					u64 *first, void **airq_info)

{

	int i, j;

	struct airq_info *info;

	unsigned long indicator_addr = 0;

	unsigned long bit, flags;



	for (i = 0; i < MAX_AIRQ_AREAS && !indicator_addr; i++) {

		if (!airq_areas[i])

			airq_areas[i] = new_airq_info();

		info = airq_areas[i];

		if (!info)

			return 0;

		write_lock_irqsave(&info->lock, flags);

		bit = airq_iv_alloc(info->aiv, nvqs);

		if (bit == -1UL) {

			/* Not enough vacancies. */

			write_unlock_irqrestore(&info->lock, flags);

			continue;

		}

		*first = bit;

		*airq_info = info;

		indicator_addr = (unsigned long)info->aiv->vector;

		for (j = 0; j < nvqs; j++) {

			airq_iv_set_ptr(info->aiv, bit + j,

					(unsigned long)vqs[j]);

		}

		write_unlock_irqrestore(&info->lock, flags);

	}

	return indicator_addr;

}



static void virtio_ccw_drop_indicators(struct virtio_ccw_device *vcdev)

{

	struct virtio_ccw_vq_info *info;



	list_for_each_entry(info, &vcdev->virtqueues, node)

		drop_airq_indicator(info->vq, vcdev->airq_info);

}



static int doing_io(struct virtio_ccw_device *vcdev, __u32 flag)

{

	unsigned long flags;
@@ -145,6 +293,51 @@ static int ccw_io_helper(struct virtio_ccw_device *vcdev, 
	return ret ? ret : vcdev->err;

}



static void virtio_ccw_drop_indicator(struct virtio_ccw_device *vcdev,

				      struct ccw1 *ccw)

{

	int ret;

	unsigned long *indicatorp = NULL;

	struct virtio_thinint_area *thinint_area = NULL;

	struct airq_info *airq_info = vcdev->airq_info;



	if (vcdev->is_thinint) {

		thinint_area = kzalloc(sizeof(*thinint_area),

				       GFP_DMA | GFP_KERNEL);

		if (!thinint_area)

			return;

		thinint_area->summary_indicator =

			(unsigned long) &airq_info->summary_indicator;

		thinint_area->isc = VIRTIO_AIRQ_ISC;

		ccw->cmd_code = CCW_CMD_SET_IND_ADAPTER;

		ccw->count = sizeof(*thinint_area);

		ccw->cda = (__u32)(unsigned long) thinint_area;

	} else {

		indicatorp = kmalloc(sizeof(&vcdev->indicators),

				     GFP_DMA | GFP_KERNEL);

		if (!indicatorp)

			return;

		*indicatorp = 0;

		ccw->cmd_code = CCW_CMD_SET_IND;

		ccw->count = sizeof(vcdev->indicators);

		ccw->cda = (__u32)(unsigned long) indicatorp;

	}

	/* Deregister indicators from host. */

	vcdev->indicators = 0;

	ccw->flags = 0;

	ret = ccw_io_helper(vcdev, ccw,

			    vcdev->is_thinint ?

			    VIRTIO_CCW_DOING_SET_IND_ADAPTER :

			    VIRTIO_CCW_DOING_SET_IND);

	if (ret && (ret != -ENODEV))

		dev_info(&vcdev->cdev->dev,

			 "Failed to deregister indicators (%d)\n", ret);

	else if (vcdev->is_thinint)

		virtio_ccw_drop_indicators(vcdev);

	kfree(indicatorp);

	kfree(thinint_area);

}



static inline long do_kvm_notify(struct subchannel_id schid,

				 unsigned long queue_index,

				 long cookie)
@@ -232,11 +425,13 @@ static void virtio_ccw_del_vqs(struct virtio_device *vdev) 
{

	struct virtqueue *vq, *n;

	struct ccw1 *ccw;

	struct virtio_ccw_device *vcdev = to_vc_device(vdev);



	ccw = kzalloc(sizeof(*ccw), GFP_DMA | GFP_KERNEL);

	if (!ccw)

		return;



	virtio_ccw_drop_indicator(vcdev, ccw);



	list_for_each_entry_safe(vq, n, &vdev->vqs, list)

		virtio_ccw_del_vq(vq, ccw);
@@ -326,6 +521,54 @@ static struct virtqueue *virtio_ccw_setup_vq(struct virtio_device *vdev, 
	return ERR_PTR(err);

}



static int virtio_ccw_register_adapter_ind(struct virtio_ccw_device *vcdev,

					   struct virtqueue *vqs[], int nvqs,

					   struct ccw1 *ccw)

{

	int ret;

	struct virtio_thinint_area *thinint_area = NULL;

	struct airq_info *info;



	thinint_area = kzalloc(sizeof(*thinint_area), GFP_DMA | GFP_KERNEL);

	if (!thinint_area) {

		ret = -ENOMEM;

		goto out;

	}

	/* Try to get an indicator. */

	thinint_area->indicator = get_airq_indicator(vqs, nvqs,

						     &thinint_area->bit_nr,

						     &vcdev->airq_info);

	if (!thinint_area->indicator) {

		ret = -ENOSPC;

		goto out;

	}

	info = vcdev->airq_info;

	thinint_area->summary_indicator =

		(unsigned long) &info->summary_indicator;

	thinint_area->isc = VIRTIO_AIRQ_ISC;

	ccw->cmd_code = CCW_CMD_SET_IND_ADAPTER;

	ccw->flags = CCW_FLAG_SLI;

	ccw->count = sizeof(*thinint_area);

	ccw->cda = (__u32)(unsigned long)thinint_area;

	ret = ccw_io_helper(vcdev, ccw, VIRTIO_CCW_DOING_SET_IND_ADAPTER);

	if (ret) {

		if (ret == -EOPNOTSUPP) {

			/*

			 * The host does not support adapter interrupts

			 * for virtio-ccw, stop trying.

			 */

			virtio_ccw_use_airq = 0;

			pr_info("Adapter interrupts unsupported on host\n");

		} else

			dev_warn(&vcdev->cdev->dev,

				 "enabling adapter interrupts = %d\n", ret);

		virtio_ccw_drop_indicators(vcdev);

	}

out:

	kfree(thinint_area);

	return ret;

}



static int virtio_ccw_find_vqs(struct virtio_device *vdev, unsigned nvqs,

			       struct virtqueue *vqs[],

			       vq_callback_t *callbacks[],
@@ -355,6 +598,13 @@ static int virtio_ccw_find_vqs(struct virtio_device *vdev, unsigned nvqs, 
	if (!indicatorp)

		goto out;

	*indicatorp = (unsigned long) &vcdev->indicators;

	if (vcdev->is_thinint) {

		ret = virtio_ccw_register_adapter_ind(vcdev, vqs, nvqs, ccw);

		if (ret)

			/* no error, just fall back to legacy interrupts */

			vcdev->is_thinint = 0;

	}

	if (!vcdev->is_thinint) {

		/* Register queue indicators with host. */

		vcdev->indicators = 0;

		ccw->cmd_code = CCW_CMD_SET_IND;
@@ -364,6 +614,7 @@ static int virtio_ccw_find_vqs(struct virtio_device *vdev, unsigned nvqs, 
		ret = ccw_io_helper(vcdev, ccw, VIRTIO_CCW_DOING_SET_IND);

		if (ret)

			goto out;

	}

	/* Register indicators2 with host for config changes */

	*indicatorp = (unsigned long) &vcdev->indicators2;

	vcdev->indicators2 = 0;
@@ -665,6 +916,7 @@ static void virtio_ccw_int_handler(struct ccw_device *cdev, 
		case VIRTIO_CCW_DOING_SET_CONF_IND:

		case VIRTIO_CCW_DOING_RESET:

		case VIRTIO_CCW_DOING_READ_VQ_CONF:

		case VIRTIO_CCW_DOING_SET_IND_ADAPTER:

			vcdev->curr_io &= ~activity;

			wake_up(&vcdev->wait_q);

			break;
@@ -795,6 +1047,8 @@ static int virtio_ccw_online(struct ccw_device *cdev) 
		goto out_free;

	}



	vcdev->is_thinint = virtio_ccw_use_airq; /* at least try */



	vcdev->vdev.dev.parent = &cdev->dev;

	vcdev->vdev.dev.release = virtio_ccw_release_dev;

	vcdev->vdev.config = &virtio_ccw_config_ops;
@@ -956,6 +1210,10 @@ module_init(virtio_ccw_init); 


static void __exit virtio_ccw_exit(void)

{

	int i;



	ccw_driver_unregister(&virtio_ccw_driver);

	for (i = 0; i < MAX_AIRQ_AREAS; i++)

		destroy_airq_info(airq_areas[i]);

}

module_exit(virtio_ccw_exit);