xen/events: use the FIFO-based ABI if available (1fe56551) · Commits · 戴 / test

drivers/xen/events/Makefile

+1 −0

Original line number	Diff line number	Diff line
		@@ -2,3 +2,4 @@ obj-y += events.o

		events-y += events_base.o
		events-y += events_2l.o
		events-y += events_fifo.o

drivers/xen/events/events_base.c

+13 −1

Original line number	Diff line number	Diff line
		@@ -1563,6 +1563,7 @@ void xen_irq_resume(void)

		/* New event-channel space is not 'live' yet. */
		xen_evtchn_mask_all();
		xen_evtchn_resume();

		/* No IRQ <-> event-channel mappings. */
		list_for_each_entry(info, &xen_irq_list_head, list)
		@@ -1659,8 +1660,19 @@ void xen_callback_vector(void)
		void xen_callback_vector(void) {}
		#endif

		#undef MODULE_PARAM_PREFIX
		#define MODULE_PARAM_PREFIX "xen."

		static bool fifo_events = true;
		module_param(fifo_events, bool, 0);

		void __init xen_init_IRQ(void)
		{
		int ret = -EINVAL;

		if (fifo_events)
		ret = xen_evtchn_fifo_init();
		if (ret < 0)
		xen_evtchn_2l_init();

		evtchn_to_irq = kcalloc(EVTCHN_ROW(xen_evtchn_max_channels()),

drivers/xen/events/events_fifo.c

0 → 100644

+426 −0

Original line number	Diff line number	Diff line
		/*
		* 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;
		}

drivers/xen/events/events_internal.h

+8 −0

Original line number	Diff line number	Diff line
		@@ -69,6 +69,7 @@ struct evtchn_ops {
		void (*unmask)(unsigned port);

		void (*handle_events)(unsigned cpu);
		void (*resume)(void);
		};

		extern const struct evtchn_ops *evtchn_ops;
		@@ -137,6 +138,13 @@ static inline void xen_evtchn_handle_events(unsigned cpu)
		return evtchn_ops->handle_events(cpu);
		}

		static inline void xen_evtchn_resume(void)
		{
		if (evtchn_ops->resume)
		evtchn_ops->resume();
		}

		void xen_evtchn_2l_init(void);
		int xen_evtchn_fifo_init(void);

		#endif /* #ifndef __EVENTS_INTERNAL_H__ */

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