summaryrefslogtreecommitdiffstats
path: root/drivers/xen/events/events_fifo.c
diff options
context:
space:
mode:
Diffstat (limited to 'drivers/xen/events/events_fifo.c')
-rw-r--r--drivers/xen/events/events_fifo.c426
1 files changed, 426 insertions, 0 deletions
diff --git a/drivers/xen/events/events_fifo.c b/drivers/xen/events/events_fifo.c
new file mode 100644
index 0000000..e2bf957
--- /dev/null
+++ b/drivers/xen/events/events_fifo.c
@@ -0,0 +1,426 @@
+/*
+ * 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/module.h>
+#include <linux/smp.h>
+#include <linux/percpu.h>
+#include <linux/cpu.h>
+
+#include <asm/sync_bitops.h>
+#include <asm/xen/hypercall.h>
+#include <asm/xen/hypervisor.h>
+#include <asm/xen/page.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 "events_internal.h"
+
+#define EVENT_WORDS_PER_PAGE (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;
+
+#define BM(w) ((unsigned long *)(w))
+
+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 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 = -ENOMEM;
+
+ 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)
+ 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_mfn(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_PENDING, BM(word));
+}
+
+static void evtchn_fifo_set_pending(unsigned port)
+{
+ event_word_t *word = event_word_from_port(port);
+ sync_set_bit(EVTCHN_FIFO_PENDING, 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_PENDING, BM(word));
+}
+
+static bool evtchn_fifo_test_and_set_mask(unsigned port)
+{
+ event_word_t *word = event_word_from_port(port);
+ return sync_test_and_set_bit(EVTCHN_FIFO_MASKED, BM(word));
+}
+
+static void evtchn_fifo_mask(unsigned port)
+{
+ event_word_t *word = event_word_from_port(port);
+ sync_set_bit(EVTCHN_FIFO_MASKED, BM(word));
+}
+
+/*
+ * Clear MASKED, spinning if BUSY is set.
+ */
+static void clear_masked(volatile event_word_t *word)
+{
+ event_word_t new, old, w;
+
+ w = *word;
+
+ do {
+ old = w & ~(1 << EVTCHN_FIFO_BUSY);
+ new = old & ~(1 << EVTCHN_FIFO_MASKED);
+ w = sync_cmpxchg(word, old, new);
+ } while (w != old);
+}
+
+static void evtchn_fifo_unmask(unsigned port)
+{
+ event_word_t *word = event_word_from_port(port);
+
+ BUG_ON(!irqs_disabled());
+
+ clear_masked(word);
+ if (sync_test_bit(EVTCHN_FIFO_PENDING, BM(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 handle_irq_for_port(unsigned port)
+{
+ int irq;
+ struct irq_desc *desc;
+
+ irq = get_evtchn_to_irq(port);
+ if (irq != -1) {
+ desc = irq_to_desc(irq);
+ if (desc)
+ generic_handle_irq_desc(irq, desc);
+ }
+}
+
+static void consume_one_event(unsigned cpu,
+ struct evtchn_fifo_control_block *control_block,
+ unsigned priority, uint32_t *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) {
+ 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, BM(ready));
+
+ if (sync_test_bit(EVTCHN_FIFO_PENDING, BM(word))
+ && !sync_test_bit(EVTCHN_FIFO_MASKED, BM(word)))
+ handle_irq_for_port(port);
+
+ q->head[priority] = head;
+}
+
+static void evtchn_fifo_handle_events(unsigned cpu)
+{
+ struct evtchn_fifo_control_block *control_block;
+ uint32_t ready;
+ unsigned q;
+
+ control_block = per_cpu(cpu_control_block, cpu);
+
+ ready = xchg(&control_block->ready, 0);
+
+ while (ready) {
+ q = find_first_bit(BM(&ready), EVTCHN_FIFO_MAX_QUEUES);
+ consume_one_event(cpu, control_block, q, &ready);
+ ready |= xchg(&control_block->ready, 0);
+ }
+}
+
+static void evtchn_fifo_resume(void)
+{
+ unsigned cpu;
+
+ for_each_possible_cpu(cpu) {
+ void *control_block = per_cpu(cpu_control_block, cpu);
+ struct evtchn_init_control init_control;
+ 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;
+ }
+
+ init_control.control_gfn = virt_to_mfn(control_block);
+ init_control.offset = 0;
+ init_control.vcpu = cpu;
+
+ ret = HYPERVISOR_event_channel_op(EVTCHNOP_init_control,
+ &init_control);
+ if (ret < 0)
+ BUG();
+ }
+
+ /*
+ * 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 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,
+ .test_and_set_mask = evtchn_fifo_test_and_set_mask,
+ .mask = evtchn_fifo_mask,
+ .unmask = evtchn_fifo_unmask,
+ .handle_events = evtchn_fifo_handle_events,
+ .resume = evtchn_fifo_resume,
+};
+
+static int __cpuinit evtchn_fifo_init_control_block(unsigned cpu)
+{
+ struct page *control_block = NULL;
+ struct evtchn_init_control init_control;
+ int ret = -ENOMEM;
+
+ control_block = alloc_page(GFP_KERNEL|__GFP_ZERO);
+ if (control_block == NULL)
+ goto error;
+
+ init_control.control_gfn = virt_to_mfn(page_address(control_block));
+ init_control.offset = 0;
+ init_control.vcpu = cpu;
+
+ ret = HYPERVISOR_event_channel_op(EVTCHNOP_init_control, &init_control);
+ if (ret < 0)
+ goto error;
+
+ per_cpu(cpu_control_block, cpu) = page_address(control_block);
+
+ return 0;
+
+ error:
+ __free_page(control_block);
+ return ret;
+}
+
+static int __cpuinit evtchn_fifo_cpu_notification(struct notifier_block *self,
+ unsigned long action,
+ void *hcpu)
+{
+ int cpu = (long)hcpu;
+ int ret = 0;
+
+ switch (action) {
+ case CPU_UP_PREPARE:
+ if (!per_cpu(cpu_control_block, cpu))
+ ret = evtchn_fifo_init_control_block(cpu);
+ break;
+ default:
+ break;
+ }
+ return ret < 0 ? NOTIFY_BAD : NOTIFY_OK;
+}
+
+static struct notifier_block evtchn_fifo_cpu_notifier __cpuinitdata = {
+ .notifier_call = evtchn_fifo_cpu_notification,
+};
+
+int __init xen_evtchn_fifo_init(void)
+{
+ int cpu = get_cpu();
+ int ret;
+
+ ret = evtchn_fifo_init_control_block(cpu);
+ if (ret < 0)
+ goto out;
+
+ pr_info("Using FIFO-based ABI\n");
+
+ evtchn_ops = &evtchn_ops_fifo;
+
+ register_cpu_notifier(&evtchn_fifo_cpu_notifier);
+out:
+ put_cpu();
+ return ret;
+}
OpenPOWER on IntegriCloud