1 // SPDX-License-Identifier: GPL-2.0 OR MIT 2 /* 3 * Copyright 2014-2022 Advanced Micro Devices, Inc. 4 * 5 * Permission is hereby granted, free of charge, to any person obtaining a 6 * copy of this software and associated documentation files (the "Software"), 7 * to deal in the Software without restriction, including without limitation 8 * the rights to use, copy, modify, merge, publish, distribute, sublicense, 9 * and/or sell copies of the Software, and to permit persons to whom the 10 * Software is furnished to do so, subject to the following conditions: 11 * 12 * The above copyright notice and this permission notice shall be included in 13 * all copies or substantial portions of the Software. 14 * 15 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR 16 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 17 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL 18 * THE COPYRIGHT HOLDER(S) OR AUTHOR(S) BE LIABLE FOR ANY CLAIM, DAMAGES OR 19 * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, 20 * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR 21 * OTHER DEALINGS IN THE SOFTWARE. 22 */ 23 24 /* 25 * KFD Interrupts. 26 * 27 * AMD GPUs deliver interrupts by pushing an interrupt description onto the 28 * interrupt ring and then sending an interrupt. KGD receives the interrupt 29 * in ISR and sends us a pointer to each new entry on the interrupt ring. 30 * 31 * We generally can't process interrupt-signaled events from ISR, so we call 32 * out to each interrupt client module (currently only the scheduler) to ask if 33 * each interrupt is interesting. If they return true, then it requires further 34 * processing so we copy it to an internal interrupt ring and call each 35 * interrupt client again from a work-queue. 36 * 37 * There's no acknowledgment for the interrupts we use. The hardware simply 38 * queues a new interrupt each time without waiting. 39 * 40 * The fixed-size internal queue means that it's possible for us to lose 41 * interrupts because we have no back-pressure to the hardware. 42 */ 43 44 #include <linux/slab.h> 45 #include <linux/device.h> 46 #include <linux/kfifo.h> 47 #include "kfd_priv.h" 48 49 #define KFD_IH_NUM_ENTRIES 8192 50 51 static void interrupt_wq(struct work_struct *); 52 53 int kfd_interrupt_init(struct kfd_dev *kfd) 54 { 55 int r; 56 57 r = kfifo_alloc(&kfd->ih_fifo, 58 KFD_IH_NUM_ENTRIES * kfd->device_info.ih_ring_entry_size, 59 GFP_KERNEL); 60 if (r) { 61 dev_err(kfd->adev->dev, "Failed to allocate IH fifo\n"); 62 return r; 63 } 64 65 kfd->ih_wq = alloc_workqueue("KFD IH", WQ_HIGHPRI, 1); 66 if (unlikely(!kfd->ih_wq)) { 67 kfifo_free(&kfd->ih_fifo); 68 dev_err(kfd->adev->dev, "Failed to allocate KFD IH workqueue\n"); 69 return -ENOMEM; 70 } 71 spin_lock_init(&kfd->interrupt_lock); 72 73 INIT_WORK(&kfd->interrupt_work, interrupt_wq); 74 75 kfd->interrupts_active = true; 76 77 /* 78 * After this function returns, the interrupt will be enabled. This 79 * barrier ensures that the interrupt running on a different processor 80 * sees all the above writes. 81 */ 82 smp_wmb(); 83 84 return 0; 85 } 86 87 void kfd_interrupt_exit(struct kfd_dev *kfd) 88 { 89 /* 90 * Stop the interrupt handler from writing to the ring and scheduling 91 * workqueue items. The spinlock ensures that any interrupt running 92 * after we have unlocked sees interrupts_active = false. 93 */ 94 unsigned long flags; 95 96 spin_lock_irqsave(&kfd->interrupt_lock, flags); 97 kfd->interrupts_active = false; 98 spin_unlock_irqrestore(&kfd->interrupt_lock, flags); 99 100 /* 101 * flush_work ensures that there are no outstanding 102 * work-queue items that will access interrupt_ring. New work items 103 * can't be created because we stopped interrupt handling above. 104 */ 105 flush_workqueue(kfd->ih_wq); 106 107 kfifo_free(&kfd->ih_fifo); 108 } 109 110 /* 111 * Assumption: single reader/writer. This function is not re-entrant 112 */ 113 bool enqueue_ih_ring_entry(struct kfd_dev *kfd, const void *ih_ring_entry) 114 { 115 int count; 116 117 count = kfifo_in(&kfd->ih_fifo, ih_ring_entry, 118 kfd->device_info.ih_ring_entry_size); 119 if (count != kfd->device_info.ih_ring_entry_size) { 120 dev_dbg_ratelimited(kfd->adev->dev, 121 "Interrupt ring overflow, dropping interrupt %d\n", 122 count); 123 return false; 124 } 125 126 return true; 127 } 128 129 /* 130 * Assumption: single reader/writer. This function is not re-entrant 131 */ 132 static bool dequeue_ih_ring_entry(struct kfd_dev *kfd, void *ih_ring_entry) 133 { 134 int count; 135 136 count = kfifo_out(&kfd->ih_fifo, ih_ring_entry, 137 kfd->device_info.ih_ring_entry_size); 138 139 WARN_ON(count && count != kfd->device_info.ih_ring_entry_size); 140 141 return count == kfd->device_info.ih_ring_entry_size; 142 } 143 144 static void interrupt_wq(struct work_struct *work) 145 { 146 struct kfd_dev *dev = container_of(work, struct kfd_dev, 147 interrupt_work); 148 uint32_t ih_ring_entry[KFD_MAX_RING_ENTRY_SIZE]; 149 unsigned long start_jiffies = jiffies; 150 151 if (dev->device_info.ih_ring_entry_size > sizeof(ih_ring_entry)) { 152 dev_err_once(dev->adev->dev, "Ring entry too small\n"); 153 return; 154 } 155 156 while (dequeue_ih_ring_entry(dev, ih_ring_entry)) { 157 dev->device_info.event_interrupt_class->interrupt_wq(dev, 158 ih_ring_entry); 159 if (time_is_before_jiffies(start_jiffies + HZ)) { 160 /* If we spent more than a second processing signals, 161 * reschedule the worker to avoid soft-lockup warnings 162 */ 163 queue_work(dev->ih_wq, &dev->interrupt_work); 164 break; 165 } 166 } 167 } 168 169 bool interrupt_is_wanted(struct kfd_dev *dev, 170 const uint32_t *ih_ring_entry, 171 uint32_t *patched_ihre, bool *flag) 172 { 173 /* integer and bitwise OR so there is no boolean short-circuiting */ 174 unsigned int wanted = 0; 175 176 wanted |= dev->device_info.event_interrupt_class->interrupt_isr(dev, 177 ih_ring_entry, patched_ihre, flag); 178 179 return wanted != 0; 180 } 181