![Paul Gortmaker](/assets/img/avatar_default.png)
Code that uses no modular facilities whatsoever should not be sourcing module.h at all, since that header drags in a bunch of other headers with it. Similarly, code that is not explicitly using modular facilities like module_init() but only is declaring module_param setup variables should be using moduleparam.h and not the larger module.h file for that. In making this change, we also uncover an implicit use of BUG() in inline fcns within arch/arm/include/asm/xen/hypercall.h so we explicitly source <linux/bug.h> for that file now. Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com> Reviewed-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com> Signed-off-by: David Vrabel <david.vrabel@citrix.com>
464 lines
11 KiB
C
464 lines
11 KiB
C
/*
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* Xen event channels (FIFO-based ABI)
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*
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* Copyright (C) 2013 Citrix Systems R&D ltd.
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*
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* This source code is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License as
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* published by the Free Software Foundation; either version 2 of the
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* License, or (at your option) any later version.
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*
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* Or, when distributed separately from the Linux kernel or
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* incorporated into other software packages, subject to the following
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* license:
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this source file (the "Software"), to deal in the Software without
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* restriction, including without limitation the rights to use, copy, modify,
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* merge, publish, distribute, sublicense, and/or sell copies of the Software,
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* and to permit persons to whom the Software is furnished to do so, subject to
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* the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in
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* all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
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* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
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* IN THE SOFTWARE.
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*/
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#define pr_fmt(fmt) "xen:" KBUILD_MODNAME ": " fmt
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#include <linux/linkage.h>
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#include <linux/interrupt.h>
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#include <linux/irq.h>
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#include <linux/smp.h>
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#include <linux/percpu.h>
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#include <linux/cpu.h>
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#include <asm/barrier.h>
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#include <asm/sync_bitops.h>
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#include <asm/xen/hypercall.h>
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#include <asm/xen/hypervisor.h>
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#include <xen/xen.h>
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#include <xen/xen-ops.h>
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#include <xen/events.h>
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#include <xen/interface/xen.h>
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#include <xen/interface/event_channel.h>
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#include <xen/page.h>
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#include "events_internal.h"
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#define EVENT_WORDS_PER_PAGE (XEN_PAGE_SIZE / sizeof(event_word_t))
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#define MAX_EVENT_ARRAY_PAGES (EVTCHN_FIFO_NR_CHANNELS / EVENT_WORDS_PER_PAGE)
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struct evtchn_fifo_queue {
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uint32_t head[EVTCHN_FIFO_MAX_QUEUES];
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};
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static DEFINE_PER_CPU(struct evtchn_fifo_control_block *, cpu_control_block);
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static DEFINE_PER_CPU(struct evtchn_fifo_queue, cpu_queue);
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static event_word_t *event_array[MAX_EVENT_ARRAY_PAGES] __read_mostly;
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static unsigned event_array_pages __read_mostly;
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/*
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* sync_set_bit() and friends must be unsigned long aligned.
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*/
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#if BITS_PER_LONG > 32
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#define BM(w) (unsigned long *)((unsigned long)w & ~0x7UL)
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#define EVTCHN_FIFO_BIT(b, w) \
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(((unsigned long)w & 0x4UL) ? (EVTCHN_FIFO_ ##b + 32) : EVTCHN_FIFO_ ##b)
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#else
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#define BM(w) ((unsigned long *)(w))
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#define EVTCHN_FIFO_BIT(b, w) EVTCHN_FIFO_ ##b
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#endif
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static inline event_word_t *event_word_from_port(unsigned port)
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{
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unsigned i = port / EVENT_WORDS_PER_PAGE;
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return event_array[i] + port % EVENT_WORDS_PER_PAGE;
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}
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static unsigned evtchn_fifo_max_channels(void)
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{
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return EVTCHN_FIFO_NR_CHANNELS;
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}
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static unsigned evtchn_fifo_nr_channels(void)
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{
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return event_array_pages * EVENT_WORDS_PER_PAGE;
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}
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static int init_control_block(int cpu,
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struct evtchn_fifo_control_block *control_block)
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{
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struct evtchn_fifo_queue *q = &per_cpu(cpu_queue, cpu);
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struct evtchn_init_control init_control;
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unsigned int i;
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/* Reset the control block and the local HEADs. */
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clear_page(control_block);
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for (i = 0; i < EVTCHN_FIFO_MAX_QUEUES; i++)
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q->head[i] = 0;
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init_control.control_gfn = virt_to_gfn(control_block);
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init_control.offset = 0;
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init_control.vcpu = cpu;
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return HYPERVISOR_event_channel_op(EVTCHNOP_init_control, &init_control);
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}
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static void free_unused_array_pages(void)
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{
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unsigned i;
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for (i = event_array_pages; i < MAX_EVENT_ARRAY_PAGES; i++) {
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if (!event_array[i])
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break;
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free_page((unsigned long)event_array[i]);
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event_array[i] = NULL;
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}
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}
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static void init_array_page(event_word_t *array_page)
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{
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unsigned i;
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for (i = 0; i < EVENT_WORDS_PER_PAGE; i++)
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array_page[i] = 1 << EVTCHN_FIFO_MASKED;
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}
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static int evtchn_fifo_setup(struct irq_info *info)
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{
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unsigned port = info->evtchn;
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unsigned new_array_pages;
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int ret;
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new_array_pages = port / EVENT_WORDS_PER_PAGE + 1;
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if (new_array_pages > MAX_EVENT_ARRAY_PAGES)
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return -EINVAL;
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while (event_array_pages < new_array_pages) {
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void *array_page;
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struct evtchn_expand_array expand_array;
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/* Might already have a page if we've resumed. */
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array_page = event_array[event_array_pages];
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if (!array_page) {
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array_page = (void *)__get_free_page(GFP_KERNEL);
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if (array_page == NULL) {
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ret = -ENOMEM;
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goto error;
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}
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event_array[event_array_pages] = array_page;
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}
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/* Mask all events in this page before adding it. */
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init_array_page(array_page);
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expand_array.array_gfn = virt_to_gfn(array_page);
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ret = HYPERVISOR_event_channel_op(EVTCHNOP_expand_array, &expand_array);
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if (ret < 0)
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goto error;
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event_array_pages++;
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}
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return 0;
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error:
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if (event_array_pages == 0)
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panic("xen: unable to expand event array with initial page (%d)\n", ret);
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else
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pr_err("unable to expand event array (%d)\n", ret);
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free_unused_array_pages();
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return ret;
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}
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static void evtchn_fifo_bind_to_cpu(struct irq_info *info, unsigned cpu)
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{
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/* no-op */
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}
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static void evtchn_fifo_clear_pending(unsigned port)
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{
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event_word_t *word = event_word_from_port(port);
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sync_clear_bit(EVTCHN_FIFO_BIT(PENDING, word), BM(word));
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}
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static void evtchn_fifo_set_pending(unsigned port)
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{
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event_word_t *word = event_word_from_port(port);
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sync_set_bit(EVTCHN_FIFO_BIT(PENDING, word), BM(word));
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}
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static bool evtchn_fifo_is_pending(unsigned port)
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{
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event_word_t *word = event_word_from_port(port);
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return sync_test_bit(EVTCHN_FIFO_BIT(PENDING, word), BM(word));
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}
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static bool evtchn_fifo_test_and_set_mask(unsigned port)
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{
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event_word_t *word = event_word_from_port(port);
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return sync_test_and_set_bit(EVTCHN_FIFO_BIT(MASKED, word), BM(word));
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}
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static void evtchn_fifo_mask(unsigned port)
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{
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event_word_t *word = event_word_from_port(port);
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sync_set_bit(EVTCHN_FIFO_BIT(MASKED, word), BM(word));
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}
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static bool evtchn_fifo_is_masked(unsigned port)
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{
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event_word_t *word = event_word_from_port(port);
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return sync_test_bit(EVTCHN_FIFO_BIT(MASKED, word), BM(word));
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}
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/*
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* Clear MASKED, spinning if BUSY is set.
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*/
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static void clear_masked(volatile event_word_t *word)
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{
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event_word_t new, old, w;
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w = *word;
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do {
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old = w & ~(1 << EVTCHN_FIFO_BUSY);
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new = old & ~(1 << EVTCHN_FIFO_MASKED);
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w = sync_cmpxchg(word, old, new);
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} while (w != old);
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}
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static void evtchn_fifo_unmask(unsigned port)
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{
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event_word_t *word = event_word_from_port(port);
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BUG_ON(!irqs_disabled());
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clear_masked(word);
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if (evtchn_fifo_is_pending(port)) {
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struct evtchn_unmask unmask = { .port = port };
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(void)HYPERVISOR_event_channel_op(EVTCHNOP_unmask, &unmask);
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}
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}
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static uint32_t clear_linked(volatile event_word_t *word)
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{
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event_word_t new, old, w;
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w = *word;
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do {
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old = w;
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new = (w & ~((1 << EVTCHN_FIFO_LINKED)
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| EVTCHN_FIFO_LINK_MASK));
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} while ((w = sync_cmpxchg(word, old, new)) != old);
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return w & EVTCHN_FIFO_LINK_MASK;
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}
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static void handle_irq_for_port(unsigned port)
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{
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int irq;
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irq = get_evtchn_to_irq(port);
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if (irq != -1)
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generic_handle_irq(irq);
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}
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static void consume_one_event(unsigned cpu,
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struct evtchn_fifo_control_block *control_block,
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unsigned priority, unsigned long *ready,
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bool drop)
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{
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struct evtchn_fifo_queue *q = &per_cpu(cpu_queue, cpu);
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uint32_t head;
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unsigned port;
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event_word_t *word;
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head = q->head[priority];
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/*
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* Reached the tail last time? Read the new HEAD from the
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* control block.
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*/
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if (head == 0) {
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virt_rmb(); /* Ensure word is up-to-date before reading head. */
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head = control_block->head[priority];
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}
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port = head;
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word = event_word_from_port(port);
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head = clear_linked(word);
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/*
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* If the link is non-zero, there are more events in the
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* queue, otherwise the queue is empty.
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*
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* If the queue is empty, clear this priority from our local
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* copy of the ready word.
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*/
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if (head == 0)
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clear_bit(priority, ready);
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if (evtchn_fifo_is_pending(port) && !evtchn_fifo_is_masked(port)) {
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if (unlikely(drop))
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pr_warn("Dropping pending event for port %u\n", port);
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else
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handle_irq_for_port(port);
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}
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q->head[priority] = head;
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}
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static void __evtchn_fifo_handle_events(unsigned cpu, bool drop)
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{
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struct evtchn_fifo_control_block *control_block;
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unsigned long ready;
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unsigned q;
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control_block = per_cpu(cpu_control_block, cpu);
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ready = xchg(&control_block->ready, 0);
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while (ready) {
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q = find_first_bit(&ready, EVTCHN_FIFO_MAX_QUEUES);
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consume_one_event(cpu, control_block, q, &ready, drop);
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ready |= xchg(&control_block->ready, 0);
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}
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}
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static void evtchn_fifo_handle_events(unsigned cpu)
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{
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__evtchn_fifo_handle_events(cpu, false);
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}
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static void evtchn_fifo_resume(void)
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{
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unsigned cpu;
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for_each_possible_cpu(cpu) {
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void *control_block = per_cpu(cpu_control_block, cpu);
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int ret;
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if (!control_block)
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continue;
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/*
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* If this CPU is offline, take the opportunity to
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* free the control block while it is not being
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* used.
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*/
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if (!cpu_online(cpu)) {
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free_page((unsigned long)control_block);
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per_cpu(cpu_control_block, cpu) = NULL;
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continue;
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}
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ret = init_control_block(cpu, control_block);
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if (ret < 0)
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BUG();
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}
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/*
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* The event array starts out as empty again and is extended
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* as normal when events are bound. The existing pages will
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* be reused.
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*/
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event_array_pages = 0;
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}
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static const struct evtchn_ops evtchn_ops_fifo = {
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.max_channels = evtchn_fifo_max_channels,
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.nr_channels = evtchn_fifo_nr_channels,
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.setup = evtchn_fifo_setup,
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.bind_to_cpu = evtchn_fifo_bind_to_cpu,
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.clear_pending = evtchn_fifo_clear_pending,
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.set_pending = evtchn_fifo_set_pending,
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.is_pending = evtchn_fifo_is_pending,
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.test_and_set_mask = evtchn_fifo_test_and_set_mask,
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.mask = evtchn_fifo_mask,
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.unmask = evtchn_fifo_unmask,
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.handle_events = evtchn_fifo_handle_events,
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.resume = evtchn_fifo_resume,
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};
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static int evtchn_fifo_alloc_control_block(unsigned cpu)
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{
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void *control_block = NULL;
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int ret = -ENOMEM;
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control_block = (void *)__get_free_page(GFP_KERNEL);
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if (control_block == NULL)
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goto error;
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ret = init_control_block(cpu, control_block);
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if (ret < 0)
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goto error;
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per_cpu(cpu_control_block, cpu) = control_block;
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return 0;
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error:
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free_page((unsigned long)control_block);
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return ret;
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}
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static int evtchn_fifo_cpu_notification(struct notifier_block *self,
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unsigned long action,
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void *hcpu)
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{
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int cpu = (long)hcpu;
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int ret = 0;
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switch (action) {
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case CPU_UP_PREPARE:
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if (!per_cpu(cpu_control_block, cpu))
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ret = evtchn_fifo_alloc_control_block(cpu);
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break;
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case CPU_DEAD:
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__evtchn_fifo_handle_events(cpu, true);
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break;
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default:
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break;
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}
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return ret < 0 ? NOTIFY_BAD : NOTIFY_OK;
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}
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static struct notifier_block evtchn_fifo_cpu_notifier = {
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.notifier_call = evtchn_fifo_cpu_notification,
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};
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int __init xen_evtchn_fifo_init(void)
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{
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int cpu = get_cpu();
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int ret;
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ret = evtchn_fifo_alloc_control_block(cpu);
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if (ret < 0)
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goto out;
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pr_info("Using FIFO-based ABI\n");
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evtchn_ops = &evtchn_ops_fifo;
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register_cpu_notifier(&evtchn_fifo_cpu_notifier);
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out:
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put_cpu();
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return ret;
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}
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