1 /* $NetBSD: kfd_interrupt.c,v 1.3 2021/12/18 23:44:59 riastradh Exp $ */ 2 3 /* 4 * Copyright 2014 Advanced Micro Devices, Inc. 5 * 6 * Permission is hereby granted, free of charge, to any person obtaining a 7 * copy of this software and associated documentation files (the "Software"), 8 * to deal in the Software without restriction, including without limitation 9 * the rights to use, copy, modify, merge, publish, distribute, sublicense, 10 * and/or sell copies of the Software, and to permit persons to whom the 11 * Software is furnished to do so, subject to the following conditions: 12 * 13 * The above copyright notice and this permission notice shall be included in 14 * all copies or substantial portions of the Software. 15 * 16 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR 17 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 18 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL 19 * THE COPYRIGHT HOLDER(S) OR AUTHOR(S) BE LIABLE FOR ANY CLAIM, DAMAGES OR 20 * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, 21 * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR 22 * OTHER DEALINGS IN THE SOFTWARE. 23 */ 24 25 /* 26 * KFD Interrupts. 27 * 28 * AMD GPUs deliver interrupts by pushing an interrupt description onto the 29 * interrupt ring and then sending an interrupt. KGD receives the interrupt 30 * in ISR and sends us a pointer to each new entry on the interrupt ring. 31 * 32 * We generally can't process interrupt-signaled events from ISR, so we call 33 * out to each interrupt client module (currently only the scheduler) to ask if 34 * each interrupt is interesting. If they return true, then it requires further 35 * processing so we copy it to an internal interrupt ring and call each 36 * interrupt client again from a work-queue. 37 * 38 * There's no acknowledgment for the interrupts we use. The hardware simply 39 * queues a new interrupt each time without waiting. 40 * 41 * The fixed-size internal queue means that it's possible for us to lose 42 * interrupts because we have no back-pressure to the hardware. 43 */ 44 45 #include <sys/cdefs.h> 46 __KERNEL_RCSID(0, "$NetBSD: kfd_interrupt.c,v 1.3 2021/12/18 23:44:59 riastradh Exp $"); 47 48 #include <linux/slab.h> 49 #include <linux/device.h> 50 #include <linux/kfifo.h> 51 #include "kfd_priv.h" 52 53 #define KFD_IH_NUM_ENTRIES 8192 54 55 static void interrupt_wq(struct work_struct *); 56 57 int kfd_interrupt_init(struct kfd_dev *kfd) 58 { 59 int r; 60 61 r = kfifo_alloc(&kfd->ih_fifo, 62 KFD_IH_NUM_ENTRIES * kfd->device_info->ih_ring_entry_size, 63 GFP_KERNEL); 64 if (r) { 65 dev_err(kfd_chardev(), "Failed to allocate IH fifo\n"); 66 return r; 67 } 68 69 kfd->ih_wq = alloc_workqueue("KFD IH", WQ_HIGHPRI, 1); 70 if (unlikely(!kfd->ih_wq)) { 71 kfifo_free(&kfd->ih_fifo); 72 dev_err(kfd_chardev(), "Failed to allocate KFD IH workqueue\n"); 73 return -ENOMEM; 74 } 75 spin_lock_init(&kfd->interrupt_lock); 76 77 INIT_WORK(&kfd->interrupt_work, interrupt_wq); 78 79 kfd->interrupts_active = true; 80 81 /* 82 * After this function returns, the interrupt will be enabled. This 83 * barrier ensures that the interrupt running on a different processor 84 * sees all the above writes. 85 */ 86 smp_wmb(); 87 88 return 0; 89 } 90 91 void kfd_interrupt_exit(struct kfd_dev *kfd) 92 { 93 /* 94 * Stop the interrupt handler from writing to the ring and scheduling 95 * workqueue items. The spinlock ensures that any interrupt running 96 * after we have unlocked sees interrupts_active = false. 97 */ 98 unsigned long flags; 99 100 spin_lock_irqsave(&kfd->interrupt_lock, flags); 101 kfd->interrupts_active = false; 102 spin_unlock_irqrestore(&kfd->interrupt_lock, flags); 103 104 /* 105 * flush_work ensures that there are no outstanding 106 * work-queue items that will access interrupt_ring. New work items 107 * can't be created because we stopped interrupt handling above. 108 */ 109 flush_workqueue(kfd->ih_wq); 110 111 kfifo_free(&kfd->ih_fifo); 112 } 113 114 /* 115 * Assumption: single reader/writer. This function is not re-entrant 116 */ 117 bool enqueue_ih_ring_entry(struct kfd_dev *kfd, const void *ih_ring_entry) 118 { 119 int count; 120 121 count = kfifo_in(&kfd->ih_fifo, ih_ring_entry, 122 kfd->device_info->ih_ring_entry_size); 123 if (count != kfd->device_info->ih_ring_entry_size) { 124 dev_err_ratelimited(kfd_chardev(), 125 "Interrupt ring overflow, dropping interrupt %d\n", 126 count); 127 return false; 128 } 129 130 return true; 131 } 132 133 /* 134 * Assumption: single reader/writer. This function is not re-entrant 135 */ 136 static bool dequeue_ih_ring_entry(struct kfd_dev *kfd, void *ih_ring_entry) 137 { 138 int count; 139 140 count = kfifo_out(&kfd->ih_fifo, ih_ring_entry, 141 kfd->device_info->ih_ring_entry_size); 142 143 WARN_ON(count && count != kfd->device_info->ih_ring_entry_size); 144 145 return count == kfd->device_info->ih_ring_entry_size; 146 } 147 148 static void interrupt_wq(struct work_struct *work) 149 { 150 struct kfd_dev *dev = container_of(work, struct kfd_dev, 151 interrupt_work); 152 uint32_t ih_ring_entry[KFD_MAX_RING_ENTRY_SIZE]; 153 154 if (dev->device_info->ih_ring_entry_size > sizeof(ih_ring_entry)) { 155 dev_err_once(kfd_chardev(), "Ring entry too small\n"); 156 return; 157 } 158 159 while (dequeue_ih_ring_entry(dev, ih_ring_entry)) 160 dev->device_info->event_interrupt_class->interrupt_wq(dev, 161 ih_ring_entry); 162 } 163 164 bool interrupt_is_wanted(struct kfd_dev *dev, 165 const uint32_t *ih_ring_entry, 166 uint32_t *patched_ihre, bool *flag) 167 { 168 /* integer and bitwise OR so there is no boolean short-circuiting */ 169 unsigned int wanted = 0; 170 171 wanted |= dev->device_info->event_interrupt_class->interrupt_isr(dev, 172 ih_ring_entry, patched_ihre, flag); 173 174 return wanted != 0; 175 } 176
Indexes created Sat Sep 20 22:09:52 GMT 2025