1 files changed, 439 insertions, 0 deletions
diff --git a/drivers/xen/events/events_fifo.c b/drivers/xen/events/events_fifo.c
new file mode 100644
index 000000000..360a7f8cd
--- /dev/null
+++ b/drivers/xen/events/events_fifo.c
@@ -0,0 +1,439 @@
+/*
+ * Xen event channels (FIFO-based ABI)
+ *
+ * Copyright (C) 2013 Citrix Systems R&D ltd.
+ *
+ * This source code is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of the
+ * License, or (at your option) any later version.
+ *
+ * Or, when distributed separately from the Linux kernel or
+ * incorporated into other software packages, subject to the following
+ * license:
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this source file (the "Software"), to deal in the Software without
+ * restriction, including without limitation the rights to use, copy, modify,
+ * merge, publish, distribute, sublicense, and/or sell copies of the Software,
+ * and to permit persons to whom the Software is furnished to do so, subject to
+ * the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+ * IN THE SOFTWARE.
+ */
+
+#define pr_fmt(fmt) "xen:" KBUILD_MODNAME ": " fmt
+
+#include <linux/linkage.h>
+#include <linux/interrupt.h>
+#include <linux/irq.h>
+#include <linux/smp.h>
+#include <linux/percpu.h>
+#include <linux/cpu.h>
+
+#include <asm/barrier.h>
+#include <asm/sync_bitops.h>
+#include <asm/xen/hypercall.h>
+#include <asm/xen/hypervisor.h>
+
+#include <xen/xen.h>
+#include <xen/xen-ops.h>
+#include <xen/events.h>
+#include <xen/interface/xen.h>
+#include <xen/interface/event_channel.h>
+#include <xen/page.h>
+
+#include "events_internal.h"
+
+#define EVENT_WORDS_PER_PAGE (XEN_PAGE_SIZE / sizeof(event_word_t))
+#define MAX_EVENT_ARRAY_PAGES (EVTCHN_FIFO_NR_CHANNELS / EVENT_WORDS_PER_PAGE)
+
+struct evtchn_fifo_queue {
+	uint32_t head[EVTCHN_FIFO_MAX_QUEUES];
+};
+
+static DEFINE_PER_CPU(struct evtchn_fifo_control_block *, cpu_control_block);
+static DEFINE_PER_CPU(struct evtchn_fifo_queue, cpu_queue);
+static event_word_t *event_array[MAX_EVENT_ARRAY_PAGES] __read_mostly;
+static unsigned event_array_pages __read_mostly;
+
+/*
+ * sync_set_bit() and friends must be unsigned long aligned.
+ */
+#if BITS_PER_LONG > 32
+
+#define BM(w) (unsigned long *)((unsigned long)w & ~0x7UL)
+#define EVTCHN_FIFO_BIT(b, w) \
+    (((unsigned long)w & 0x4UL) ? (EVTCHN_FIFO_ ##b + 32) : EVTCHN_FIFO_ ##b)
+
+#else
+
+#define BM(w) ((unsigned long *)(w))
+#define EVTCHN_FIFO_BIT(b, w) EVTCHN_FIFO_ ##b
+
+#endif
+
+static inline event_word_t *event_word_from_port(unsigned port)
+{
+	unsigned i = port / EVENT_WORDS_PER_PAGE;
+
+	return event_array[i] + port % EVENT_WORDS_PER_PAGE;
+}
+
+static unsigned evtchn_fifo_max_channels(void)
+{
+	return EVTCHN_FIFO_NR_CHANNELS;
+}
+
+static unsigned evtchn_fifo_nr_channels(void)
+{
+	return event_array_pages * EVENT_WORDS_PER_PAGE;
+}
+
+static int init_control_block(int cpu,
+                              struct evtchn_fifo_control_block *control_block)
+{
+	struct evtchn_fifo_queue *q = &per_cpu(cpu_queue, cpu);
+	struct evtchn_init_control init_control;
+	unsigned int i;
+
+	/* Reset the control block and the local HEADs. */
+	clear_page(control_block);
+	for (i = 0; i < EVTCHN_FIFO_MAX_QUEUES; i++)
+		q->head[i] = 0;
+
+	init_control.control_gfn = virt_to_gfn(control_block);
+	init_control.offset      = 0;
+	init_control.vcpu        = xen_vcpu_nr(cpu);
+
+	return HYPERVISOR_event_channel_op(EVTCHNOP_init_control, &init_control);
+}
+
+static void free_unused_array_pages(void)
+{
+	unsigned i;
+
+	for (i = event_array_pages; i < MAX_EVENT_ARRAY_PAGES; i++) {
+		if (!event_array[i])
+			break;
+		free_page((unsigned long)event_array[i]);
+		event_array[i] = NULL;
+	}
+}
+
+static void init_array_page(event_word_t *array_page)
+{
+	unsigned i;
+
+	for (i = 0; i < EVENT_WORDS_PER_PAGE; i++)
+		array_page[i] = 1 << EVTCHN_FIFO_MASKED;
+}
+
+static int evtchn_fifo_setup(struct irq_info *info)
+{
+	unsigned port = info->evtchn;
+	unsigned new_array_pages;
+	int ret;
+
+	new_array_pages = port / EVENT_WORDS_PER_PAGE + 1;
+
+	if (new_array_pages > MAX_EVENT_ARRAY_PAGES)
+		return -EINVAL;
+
+	while (event_array_pages < new_array_pages) {
+		void *array_page;
+		struct evtchn_expand_array expand_array;
+
+		/* Might already have a page if we've resumed. */
+		array_page = event_array[event_array_pages];
+		if (!array_page) {
+			array_page = (void *)__get_free_page(GFP_KERNEL);
+			if (array_page == NULL) {
+				ret = -ENOMEM;
+				goto error;
+			}
+			event_array[event_array_pages] = array_page;
+		}
+
+		/* Mask all events in this page before adding it. */
+		init_array_page(array_page);
+
+		expand_array.array_gfn = virt_to_gfn(array_page);
+
+		ret = HYPERVISOR_event_channel_op(EVTCHNOP_expand_array, &expand_array);
+		if (ret < 0)
+			goto error;
+
+		event_array_pages++;
+	}
+	return 0;
+
+  error:
+	if (event_array_pages == 0)
+		panic("xen: unable to expand event array with initial page (%d)\n", ret);
+	else
+		pr_err("unable to expand event array (%d)\n", ret);
+	free_unused_array_pages();
+	return ret;
+}
+
+static void evtchn_fifo_bind_to_cpu(struct irq_info *info, unsigned cpu)
+{
+	/* no-op */
+}
+
+static void evtchn_fifo_clear_pending(unsigned port)
+{
+	event_word_t *word = event_word_from_port(port);
+	sync_clear_bit(EVTCHN_FIFO_BIT(PENDING, word), BM(word));
+}
+
+static void evtchn_fifo_set_pending(unsigned port)
+{
+	event_word_t *word = event_word_from_port(port);
+	sync_set_bit(EVTCHN_FIFO_BIT(PENDING, word), BM(word));
+}
+
+static bool evtchn_fifo_is_pending(unsigned port)
+{
+	event_word_t *word = event_word_from_port(port);
+	return sync_test_bit(EVTCHN_FIFO_BIT(PENDING, word), BM(word));
+}
+
+static void evtchn_fifo_mask(unsigned port)
+{
+	event_word_t *word = event_word_from_port(port);
+	sync_set_bit(EVTCHN_FIFO_BIT(MASKED, word), BM(word));
+}
+
+static bool evtchn_fifo_is_masked(unsigned port)
+{
+	event_word_t *word = event_word_from_port(port);
+	return sync_test_bit(EVTCHN_FIFO_BIT(MASKED, word), BM(word));
+}
+/*
+ * Clear MASKED if not PENDING, spinning if BUSY is set.
+ * Return true if mask was cleared.
+ */
+static bool clear_masked_cond(volatile event_word_t *word)
+{
+	event_word_t new, old, w;
+
+	w = *word;
+
+	do {
+		if (w & (1 << EVTCHN_FIFO_PENDING))
+			return false;
+
+		old = w & ~(1 << EVTCHN_FIFO_BUSY);
+		new = old & ~(1 << EVTCHN_FIFO_MASKED);
+		w = sync_cmpxchg(word, old, new);
+	} while (w != old);
+
+	return true;
+}
+
+static void evtchn_fifo_unmask(unsigned port)
+{
+	event_word_t *word = event_word_from_port(port);
+
+	BUG_ON(!irqs_disabled());
+
+	if (!clear_masked_cond(word)) {
+		struct evtchn_unmask unmask = { .port = port };
+		(void)HYPERVISOR_event_channel_op(EVTCHNOP_unmask, &unmask);
+	}
+}
+
+static uint32_t clear_linked(volatile event_word_t *word)
+{
+	event_word_t new, old, w;
+
+	w = *word;
+
+	do {
+		old = w;
+		new = (w & ~((1 << EVTCHN_FIFO_LINKED)
+			     | EVTCHN_FIFO_LINK_MASK));
+	} while ((w = sync_cmpxchg(word, old, new)) != old);
+
+	return w & EVTCHN_FIFO_LINK_MASK;
+}
+
+static void consume_one_event(unsigned cpu, struct evtchn_loop_ctrl *ctrl,
+			      struct evtchn_fifo_control_block *control_block,
+			      unsigned priority, unsigned long *ready)
+{
+	struct evtchn_fifo_queue *q = &per_cpu(cpu_queue, cpu);
+	uint32_t head;
+	unsigned port;
+	event_word_t *word;
+
+	head = q->head[priority];
+
+	/*
+	 * Reached the tail last time?  Read the new HEAD from the
+	 * control block.
+	 */
+	if (head == 0) {
+		virt_rmb(); /* Ensure word is up-to-date before reading head. */
+		head = control_block->head[priority];
+	}
+
+	port = head;
+	word = event_word_from_port(port);
+	head = clear_linked(word);
+
+	/*
+	 * If the link is non-zero, there are more events in the
+	 * queue, otherwise the queue is empty.
+	 *
+	 * If the queue is empty, clear this priority from our local
+	 * copy of the ready word.
+	 */
+	if (head == 0)
+		clear_bit(priority, ready);
+
+	if (evtchn_fifo_is_pending(port) && !evtchn_fifo_is_masked(port)) {
+		if (unlikely(!ctrl))
+			pr_warn("Dropping pending event for port %u\n", port);
+		else
+			handle_irq_for_port(port, ctrl);
+	}
+
+	q->head[priority] = head;
+}
+
+static void __evtchn_fifo_handle_events(unsigned cpu,
+					struct evtchn_loop_ctrl *ctrl)
+{
+	struct evtchn_fifo_control_block *control_block;
+	unsigned long ready;
+	unsigned q;
+
+	control_block = per_cpu(cpu_control_block, cpu);
+
+	ready = xchg(&control_block->ready, 0);
+
+	while (ready) {
+		q = find_first_bit(&ready, EVTCHN_FIFO_MAX_QUEUES);
+		consume_one_event(cpu, ctrl, control_block, q, &ready);
+		ready |= xchg(&control_block->ready, 0);
+	}
+}
+
+static void evtchn_fifo_handle_events(unsigned cpu,
+				      struct evtchn_loop_ctrl *ctrl)
+{
+	__evtchn_fifo_handle_events(cpu, ctrl);
+}
+
+static void evtchn_fifo_resume(void)
+{
+	unsigned cpu;
+
+	for_each_possible_cpu(cpu) {
+		void *control_block = per_cpu(cpu_control_block, cpu);
+		int ret;
+
+		if (!control_block)
+			continue;
+
+		/*
+		 * If this CPU is offline, take the opportunity to
+		 * free the control block while it is not being
+		 * used.
+		 */
+		if (!cpu_online(cpu)) {
+			free_page((unsigned long)control_block);
+			per_cpu(cpu_control_block, cpu) = NULL;
+			continue;
+		}
+
+		ret = init_control_block(cpu, control_block);
+		BUG_ON(ret < 0);
+	}
+
+	/*
+	 * The event array starts out as empty again and is extended
+	 * as normal when events are bound.  The existing pages will
+	 * be reused.
+	 */
+	event_array_pages = 0;
+}
+
+static int evtchn_fifo_alloc_control_block(unsigned cpu)
+{
+	void *control_block = NULL;
+	int ret = -ENOMEM;
+
+	control_block = (void *)__get_free_page(GFP_KERNEL);
+	if (control_block == NULL)
+		goto error;
+
+	ret = init_control_block(cpu, control_block);
+	if (ret < 0)
+		goto error;
+
+	per_cpu(cpu_control_block, cpu) = control_block;
+
+	return 0;
+
+  error:
+	free_page((unsigned long)control_block);
+	return ret;
+}
+
+static int evtchn_fifo_percpu_init(unsigned int cpu)
+{
+	if (!per_cpu(cpu_control_block, cpu))
+		return evtchn_fifo_alloc_control_block(cpu);
+	return 0;
+}
+
+static int evtchn_fifo_percpu_deinit(unsigned int cpu)
+{
+	__evtchn_fifo_handle_events(cpu, NULL);
+	return 0;
+}
+
+static const struct evtchn_ops evtchn_ops_fifo = {
+	.max_channels      = evtchn_fifo_max_channels,
+	.nr_channels       = evtchn_fifo_nr_channels,
+	.setup             = evtchn_fifo_setup,
+	.bind_to_cpu       = evtchn_fifo_bind_to_cpu,
+	.clear_pending     = evtchn_fifo_clear_pending,
+	.set_pending       = evtchn_fifo_set_pending,
+	.is_pending        = evtchn_fifo_is_pending,
+	.mask              = evtchn_fifo_mask,
+	.unmask            = evtchn_fifo_unmask,
+	.handle_events     = evtchn_fifo_handle_events,
+	.resume            = evtchn_fifo_resume,
+	.percpu_init       = evtchn_fifo_percpu_init,
+	.percpu_deinit     = evtchn_fifo_percpu_deinit,
+};
+
+int __init xen_evtchn_fifo_init(void)
+{
+	int cpu = smp_processor_id();
+	int ret;
+
+	ret = evtchn_fifo_alloc_control_block(cpu);
+	if (ret < 0)
+		return ret;
+
+	pr_info("Using FIFO-based ABI\n");
+
+	evtchn_ops = &evtchn_ops_fifo;
+
+	return ret;
+}