forked from Minki/linux
22f12f0df8
When booting Linux as Xen guest with CONFIG_DEBUG_ATOMIC, the following
splat appears:
[ 0.002323] Mountpoint-cache hash table entries: 1024 (order: 1, 8192 bytes)
[ 0.019717] ASID allocator initialised with 65536 entries
[ 0.020019] xen:grant_table: Grant tables using version 1 layout
[ 0.020051] Grant table initialized
[ 0.020069] BUG: sleeping function called from invalid context at /data/src/linux/mm/page_alloc.c:4046
[ 0.020100] in_atomic(): 1, irqs_disabled(): 0, pid: 1, name: swapper/0
[ 0.020123] no locks held by swapper/0/1.
[ 0.020143] CPU: 0 PID: 1 Comm: swapper/0 Not tainted 4.13.0-rc5 #598
[ 0.020166] Hardware name: FVP Base (DT)
[ 0.020182] Call trace:
[ 0.020199] [<ffff00000808a5c0>] dump_backtrace+0x0/0x270
[ 0.020222] [<ffff00000808a95c>] show_stack+0x24/0x30
[ 0.020244] [<ffff000008c1ef20>] dump_stack+0xb8/0xf0
[ 0.020267] [<ffff0000081128c0>] ___might_sleep+0x1c8/0x1f8
[ 0.020291] [<ffff000008112948>] __might_sleep+0x58/0x90
[ 0.020313] [<ffff0000082171b8>] __alloc_pages_nodemask+0x1c0/0x12e8
[ 0.020338] [<ffff00000827a110>] alloc_page_interleave+0x38/0x88
[ 0.020363] [<ffff00000827a904>] alloc_pages_current+0xdc/0xf0
[ 0.020387] [<ffff000008211f38>] __get_free_pages+0x28/0x50
[ 0.020411] [<ffff0000086566a4>] evtchn_fifo_alloc_control_block+0x2c/0xa0
[ 0.020437] [<ffff0000091747b0>] xen_evtchn_fifo_init+0x38/0xb4
[ 0.020461] [<ffff0000091746c0>] xen_init_IRQ+0x44/0xc8
[ 0.020484] [<ffff000009128adc>] xen_guest_init+0x250/0x300
[ 0.020507] [<ffff000008083974>] do_one_initcall+0x44/0x130
[ 0.020531] [<ffff000009120df8>] kernel_init_freeable+0x120/0x288
[ 0.020556] [<ffff000008c31ca8>] kernel_init+0x18/0x110
[ 0.020578] [<ffff000008083710>] ret_from_fork+0x10/0x40
[ 0.020606] xen:events: Using FIFO-based ABI
[ 0.020658] Xen: initializing cpu0
[ 0.027727] Hierarchical SRCU implementation.
[ 0.036235] EFI services will not be available.
[ 0.043810] smp: Bringing up secondary CPUs ...
This is because get_cpu() in xen_evtchn_fifo_init() will disable
preemption, but __get_free_page() might sleep (GFP_ATOMIC is not set).
xen_evtchn_fifo_init() will always be called before SMP is initialized,
so {get,put}_cpu() could be replaced by a simple smp_processor_id().
This also avoid to modify evtchn_fifo_alloc_control_block that will be
called in other context.
Signed-off-by: Julien Grall <julien.grall@arm.com>
Reported-by: Andre Przywara <andre.przywara@arm.com>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Fixes: 1fe565517b
("xen/events: use the FIFO-based ABI if available")
Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
452 lines
11 KiB
C
452 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 = xen_vcpu_nr(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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BUG_ON(ret < 0);
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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 xen_evtchn_cpu_prepare(unsigned int cpu)
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{
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if (!per_cpu(cpu_control_block, cpu))
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return evtchn_fifo_alloc_control_block(cpu);
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return 0;
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}
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static int xen_evtchn_cpu_dead(unsigned int cpu)
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{
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__evtchn_fifo_handle_events(cpu, true);
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return 0;
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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 = smp_processor_id();
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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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return ret;
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pr_info("Using FIFO-based ABI\n");
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evtchn_ops = &evtchn_ops_fifo;
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cpuhp_setup_state_nocalls(CPUHP_XEN_EVTCHN_PREPARE,
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"xen/evtchn:prepare",
|
|
xen_evtchn_cpu_prepare, xen_evtchn_cpu_dead);
|
|
|
|
return ret;
|
|
}
|