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 16384 50 51 static void interrupt_wq(struct work_struct *); 52 53 int kfd_interrupt_init(struct kfd_node *node) 54 { 55 int r; 56 57 r = kfifo_alloc(&node->ih_fifo, 58 KFD_IH_NUM_ENTRIES * node->kfd->device_info.ih_ring_entry_size, 59 GFP_KERNEL); 60 if (r) { 61 dev_err(node->adev->dev, "Failed to allocate IH fifo\n"); 62 return r; 63 } 64 65 if (!node->kfd->ih_wq) { 66 node->kfd->ih_wq = alloc_workqueue("KFD IH", WQ_HIGHPRI | WQ_UNBOUND, 67 node->kfd->num_nodes); 68 if (unlikely(!node->kfd->ih_wq)) { 69 kfifo_free(&node->ih_fifo); 70 dev_err(node->adev->dev, "Failed to allocate KFD IH workqueue\n"); 71 return -ENOMEM; 72 } 73 } 74 spin_lock_init(&node->interrupt_lock); 75 76 INIT_WORK(&node->interrupt_work, interrupt_wq); 77 78 node->interrupts_active = true; 79 80 /* 81 * After this function returns, the interrupt will be enabled. This 82 * barrier ensures that the interrupt running on a different processor 83 * sees all the above writes. 84 */ 85 smp_wmb(); 86 87 return 0; 88 } 89 90 void kfd_interrupt_exit(struct kfd_node *node) 91 { 92 /* 93 * Stop the interrupt handler from writing to the ring and scheduling 94 * workqueue items. The spinlock ensures that any interrupt running 95 * after we have unlocked sees interrupts_active = false. 96 */ 97 unsigned long flags; 98 99 spin_lock_irqsave(&node->interrupt_lock, flags); 100 node->interrupts_active = false; 101 spin_unlock_irqrestore(&node->interrupt_lock, flags); 102 kfifo_free(&node->ih_fifo); 103 } 104 105 /* 106 * Assumption: single reader/writer. This function is not re-entrant 107 */ 108 bool enqueue_ih_ring_entry(struct kfd_node *node, const void *ih_ring_entry) 109 { 110 if (kfifo_is_full(&node->ih_fifo)) { 111 dev_warn_ratelimited(node->adev->dev, "KFD node %d ih_fifo overflow\n", 112 node->node_id); 113 return false; 114 } 115 116 kfifo_in(&node->ih_fifo, ih_ring_entry, node->kfd->device_info.ih_ring_entry_size); 117 return true; 118 } 119 120 /* 121 * Assumption: single reader/writer. This function is not re-entrant 122 */ 123 static bool dequeue_ih_ring_entry(struct kfd_node *node, u32 **ih_ring_entry) 124 { 125 int count; 126 127 if (kfifo_is_empty(&node->ih_fifo)) 128 return false; 129 130 count = kfifo_out_linear_ptr(&node->ih_fifo, ih_ring_entry, 131 node->kfd->device_info.ih_ring_entry_size); 132 WARN_ON(count != node->kfd->device_info.ih_ring_entry_size); 133 return count == node->kfd->device_info.ih_ring_entry_size; 134 } 135 136 static void interrupt_wq(struct work_struct *work) 137 { 138 struct kfd_node *dev = container_of(work, struct kfd_node, interrupt_work); 139 uint32_t *ih_ring_entry; 140 unsigned long start_jiffies = jiffies; 141 142 while (dequeue_ih_ring_entry(dev, &ih_ring_entry)) { 143 dev->kfd->device_info.event_interrupt_class->interrupt_wq(dev, 144 ih_ring_entry); 145 kfifo_skip_count(&dev->ih_fifo, dev->kfd->device_info.ih_ring_entry_size); 146 147 if (time_is_before_jiffies(start_jiffies + HZ)) { 148 /* If we spent more than a second processing signals, 149 * reschedule the worker to avoid soft-lockup warnings 150 */ 151 queue_work(dev->kfd->ih_wq, &dev->interrupt_work); 152 break; 153 } 154 } 155 } 156 157 bool interrupt_is_wanted(struct kfd_node *dev, 158 const uint32_t *ih_ring_entry, 159 uint32_t *patched_ihre, bool *flag) 160 { 161 /* integer and bitwise OR so there is no boolean short-circuiting */ 162 unsigned int wanted = 0; 163 164 wanted |= dev->kfd->device_info.event_interrupt_class->interrupt_isr(dev, 165 ih_ring_entry, patched_ihre, flag); 166 167 return wanted != 0; 168 } 169