Commit 5c2e7a0a authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Merge tag 'for-linus-5.12b-rc1-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip 

Pull more xen updates from Juergen Gross:

 - A small series for Xen event channels adding some sysfs nodes for per
   pv-device settings and statistics, and two fixes of theoretical
   problems.

 - two minor fixes (one for an unlikely error path, one for a comment).

* tag 'for-linus-5.12b-rc1-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip:
  xen-front-pgdir-shbuf: don't record wrong grant handle upon error
  xen: Replace lkml.org links with lore
  xen/evtchn: use READ/WRITE_ONCE() for accessing ring indices
  xen/evtchn: use smp barriers for user event ring
  xen/events: add per-xenbus device event statistics and settings
parents d94d1400 53f131c2

Documentation/ABI/testing/sysfs-devices-xenbus

0 → 100644
+41 −0
Original line number Diff line number Diff line 
What:		/sys/devices/*/xenbus/event_channels

Date:		February 2021

Contact:	Xen Developers mailing list <xen-devel@lists.xenproject.org>

Description:

		Number of Xen event channels associated with a kernel based

		paravirtualized device frontend or backend.



What:		/sys/devices/*/xenbus/events

Date:		February 2021

Contact:	Xen Developers mailing list <xen-devel@lists.xenproject.org>

Description:

		Total number of Xen events received for a Xen pv device

		frontend or backend.



What:		/sys/devices/*/xenbus/jiffies_eoi_delayed

Date:		February 2021

Contact:	Xen Developers mailing list <xen-devel@lists.xenproject.org>

Description:

		Summed up time in jiffies the EOI of an interrupt for a Xen

		pv device has been delayed in order to avoid stalls due to

		event storms. This value rising is a first sign for a rogue

		other end of the pv device.



What:		/sys/devices/*/xenbus/spurious_events

Date:		February 2021

Contact:	Xen Developers mailing list <xen-devel@lists.xenproject.org>

Description:

		Number of events received for a Xen pv device which did not

		require any action. Too many spurious events in a row will

		trigger delayed EOI processing.



What:		/sys/devices/*/xenbus/spurious_threshold

Date:		February 2021

Contact:	Xen Developers mailing list <xen-devel@lists.xenproject.org>

Description:

		Controls the tolerated number of subsequent spurious events

		before delayed EOI processing is triggered for a Xen pv

		device. Default is 1. This can be modified in case the other

		end of the pv device is issuing spurious events on a regular

		basis and is known not to be malicious on purpose. Raising

		the value for such cases can improve pv device performance.

drivers/xen/events/events_base.c

+25 −2
Original line number Diff line number Diff line
@@ -323,6 +323,8 @@ static int xen_irq_info_evtchn_setup(unsigned irq, 


	ret = xen_irq_info_common_setup(info, irq, IRQT_EVTCHN, evtchn, 0);

	info->u.interdomain = dev;

	if (dev)

		atomic_inc(&dev->event_channels);



	return ret;

}
@@ -568,18 +570,28 @@ static void xen_irq_lateeoi_locked(struct irq_info *info, bool spurious) 
		return;



	if (spurious) {

		struct xenbus_device *dev = info->u.interdomain;

		unsigned int threshold = 1;



		if (dev && dev->spurious_threshold)

			threshold = dev->spurious_threshold;



		if ((1 << info->spurious_cnt) < (HZ << 2)) {

			if (info->spurious_cnt != 0xFF)

				info->spurious_cnt++;

		}

		if (info->spurious_cnt > 1) {

			delay = 1 << (info->spurious_cnt - 2);

		if (info->spurious_cnt > threshold) {

			delay = 1 << (info->spurious_cnt - 1 - threshold);

			if (delay > HZ)

				delay = HZ;

			if (!info->eoi_time)

				info->eoi_cpu = smp_processor_id();

			info->eoi_time = get_jiffies_64() + delay;

			if (dev)

				atomic_add(delay, &dev->jiffies_eoi_delayed);

		}

		if (dev)

			atomic_inc(&dev->spurious_events);

	} else {

		info->spurious_cnt = 0;

	}
@@ -908,6 +920,7 @@ static void __unbind_from_irq(unsigned int irq) 


	if (VALID_EVTCHN(evtchn)) {

		unsigned int cpu = cpu_from_irq(irq);

		struct xenbus_device *dev;



		xen_evtchn_close(evtchn);
@@ -918,6 +931,11 @@ static void __unbind_from_irq(unsigned int irq) 
		case IRQT_IPI:

			per_cpu(ipi_to_irq, cpu)[ipi_from_irq(irq)] = -1;

			break;

		case IRQT_EVTCHN:

			dev = info->u.interdomain;

			if (dev)

				atomic_dec(&dev->event_channels);

			break;

		default:

			break;

		}
@@ -1581,6 +1599,7 @@ void handle_irq_for_port(evtchn_port_t port, struct evtchn_loop_ctrl *ctrl) 
{

	int irq;

	struct irq_info *info;

	struct xenbus_device *dev;



	irq = get_evtchn_to_irq(port);

	if (irq == -1)
@@ -1610,6 +1629,10 @@ void handle_irq_for_port(evtchn_port_t port, struct evtchn_loop_ctrl *ctrl) 


	info = info_for_irq(irq);



	dev = (info->type == IRQT_EVTCHN) ? info->u.interdomain : NULL;

	if (dev)

		atomic_inc(&dev->events);



	if (ctrl->defer_eoi) {

		info->eoi_cpu = smp_processor_id();

		info->irq_epoch = __this_cpu_read(irq_epoch);

drivers/xen/evtchn.c

+18 −11
Original line number Diff line number Diff line
@@ -162,6 +162,7 @@ static irqreturn_t evtchn_interrupt(int irq, void *data) 
{

	struct user_evtchn *evtchn = data;

	struct per_user_data *u = evtchn->user;

	unsigned int prod, cons;



	WARN(!evtchn->enabled,

	     "Interrupt for port %u, but apparently not enabled; per-user %p\n",
@@ -171,10 +172,14 @@ static irqreturn_t evtchn_interrupt(int irq, void *data) 


	spin_lock(&u->ring_prod_lock);



	if ((u->ring_prod - u->ring_cons) < u->ring_size) {

		*evtchn_ring_entry(u, u->ring_prod) = evtchn->port;

		wmb(); /* Ensure ring contents visible */

		if (u->ring_cons == u->ring_prod++) {

	prod = READ_ONCE(u->ring_prod);

	cons = READ_ONCE(u->ring_cons);



	if ((prod - cons) < u->ring_size) {

		*evtchn_ring_entry(u, prod) = evtchn->port;

		smp_wmb(); /* Ensure ring contents visible */

		WRITE_ONCE(u->ring_prod, prod + 1);

		if (cons == prod) {

			wake_up_interruptible(&u->evtchn_wait);

			kill_fasync(&u->evtchn_async_queue,

				    SIGIO, POLL_IN);
@@ -210,8 +215,8 @@ static ssize_t evtchn_read(struct file *file, char __user *buf, 
		if (u->ring_overflow)

			goto unlock_out;



		c = u->ring_cons;

		p = u->ring_prod;

		c = READ_ONCE(u->ring_cons);

		p = READ_ONCE(u->ring_prod);

		if (c != p)

			break;
@@ -221,7 +226,7 @@ static ssize_t evtchn_read(struct file *file, char __user *buf, 
			return -EAGAIN;



		rc = wait_event_interruptible(u->evtchn_wait,

					      u->ring_cons != u->ring_prod);

			READ_ONCE(u->ring_cons) != READ_ONCE(u->ring_prod));

		if (rc)

			return rc;

	}
@@ -245,13 +250,13 @@ static ssize_t evtchn_read(struct file *file, char __user *buf, 
	}



	rc = -EFAULT;

	rmb(); /* Ensure that we see the port before we copy it. */

	smp_rmb(); /* Ensure that we see the port before we copy it. */

	if (copy_to_user(buf, evtchn_ring_entry(u, c), bytes1) ||

	    ((bytes2 != 0) &&

	     copy_to_user(&buf[bytes1], &u->ring[0], bytes2)))

		goto unlock_out;



	u->ring_cons += (bytes1 + bytes2) / sizeof(evtchn_port_t);

	WRITE_ONCE(u->ring_cons, c + (bytes1 + bytes2) / sizeof(evtchn_port_t));

	rc = bytes1 + bytes2;



 unlock_out:
@@ -552,7 +557,9 @@ static long evtchn_ioctl(struct file *file, 
		/* Initialise the ring to empty. Clear errors. */

		mutex_lock(&u->ring_cons_mutex);

		spin_lock_irq(&u->ring_prod_lock);

		u->ring_cons = u->ring_prod = u->ring_overflow = 0;

		WRITE_ONCE(u->ring_cons, 0);

		WRITE_ONCE(u->ring_prod, 0);

		u->ring_overflow = 0;

		spin_unlock_irq(&u->ring_prod_lock);

		mutex_unlock(&u->ring_cons_mutex);

		rc = 0;
@@ -595,7 +602,7 @@ static __poll_t evtchn_poll(struct file *file, poll_table *wait) 
	struct per_user_data *u = file->private_data;



	poll_wait(file, &u->evtchn_wait, wait);

	if (u->ring_cons != u->ring_prod)

	if (READ_ONCE(u->ring_cons) != READ_ONCE(u->ring_prod))

		mask |= EPOLLIN | EPOLLRDNORM;

	if (u->ring_overflow)

		mask = EPOLLERR;

drivers/xen/xen-acpi-processor.c

+2 −1
Original line number Diff line number Diff line
@@ -3,7 +3,8 @@ 
 * Copyright 2012 by Oracle Inc

 * Author: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>

 *

 * This code borrows ideas from https://lkml.org/lkml/2011/11/30/249

 * This code borrows ideas from

 * https://lore.kernel.org/lkml/1322673664-14642-6-git-send-email-konrad.wilk@oracle.com

 * so many thanks go to Kevin Tian <kevin.tian@intel.com>

 * and Yu Ke <ke.yu@intel.com>.

 */

drivers/xen/xen-front-pgdir-shbuf.c

+9 −2
Original line number Diff line number Diff line
@@ -305,12 +305,19 @@ static int backend_map(struct xen_front_pgdir_shbuf *buf) 


	/* Save handles even if error, so we can unmap. */

	for (cur_page = 0; cur_page < buf->num_pages; cur_page++) {

		buf->backend_map_handles[cur_page] = map_ops[cur_page].handle;

		if (unlikely(map_ops[cur_page].status != GNTST_okay))

		if (likely(map_ops[cur_page].status == GNTST_okay)) {

			buf->backend_map_handles[cur_page] =

				map_ops[cur_page].handle;

		} else {

			buf->backend_map_handles[cur_page] =

				INVALID_GRANT_HANDLE;

			if (!ret)

				ret = -ENXIO;

			dev_err(&buf->xb_dev->dev,

				"Failed to map page %d: %d\n",

				cur_page, map_ops[cur_page].status);

		}

	}



	if (ret) {

		dev_err(&buf->xb_dev->dev,