1 /* 2 * QEMU paravirtual RDMA - Device rings 3 * 4 * Copyright (C) 2018 Oracle 5 * Copyright (C) 2018 Red Hat Inc 6 * 7 * Authors: 8 * Yuval Shaia <yuval.shaia@oracle.com> 9 * Marcel Apfelbaum <marcel@redhat.com> 10 * 11 * This work is licensed under the terms of the GNU GPL, version 2 or later. 12 * See the COPYING file in the top-level directory. 13 * 14 */ 15 16 #include "qemu/osdep.h" 17 #include "qemu/cutils.h" 18 #include "hw/pci/pci.h" 19 #include "cpu.h" 20 #include "qemu/cutils.h" 21 22 #include "trace.h" 23 24 #include "../rdma_utils.h" 25 #include "pvrdma_dev_ring.h" 26 27 int pvrdma_ring_init(PvrdmaRing *ring, const char *name, PCIDevice *dev, 28 PvrdmaRingState *ring_state, uint32_t max_elems, 29 size_t elem_sz, dma_addr_t *tbl, uint32_t npages) 30 { 31 int i; 32 int rc = 0; 33 34 pstrcpy(ring->name, MAX_RING_NAME_SZ, name); 35 ring->dev = dev; 36 ring->ring_state = ring_state; 37 ring->max_elems = max_elems; 38 ring->elem_sz = elem_sz; 39 /* TODO: Give a moment to think if we want to redo driver settings 40 qatomic_set(&ring->ring_state->prod_tail, 0); 41 qatomic_set(&ring->ring_state->cons_head, 0); 42 */ 43 ring->npages = npages; 44 ring->pages = g_new0(void *, npages); 45 46 for (i = 0; i < npages; i++) { 47 if (!tbl[i]) { 48 rdma_error_report("npages=%d but tbl[%d] is NULL", npages, i); 49 continue; 50 } 51 52 ring->pages[i] = rdma_pci_dma_map(dev, tbl[i], TARGET_PAGE_SIZE); 53 if (!ring->pages[i]) { 54 rc = -ENOMEM; 55 rdma_error_report("Failed to map to page %d in ring %s", i, name); 56 goto out_free; 57 } 58 memset(ring->pages[i], 0, TARGET_PAGE_SIZE); 59 } 60 61 goto out; 62 63 out_free: 64 while (i--) { 65 rdma_pci_dma_unmap(dev, ring->pages[i], TARGET_PAGE_SIZE); 66 } 67 g_free(ring->pages); 68 69 out: 70 return rc; 71 } 72 73 void *pvrdma_ring_next_elem_read(PvrdmaRing *ring) 74 { 75 unsigned int idx, offset; 76 const uint32_t tail = qatomic_read(&ring->ring_state->prod_tail); 77 const uint32_t head = qatomic_read(&ring->ring_state->cons_head); 78 79 if (tail & ~((ring->max_elems << 1) - 1) || 80 head & ~((ring->max_elems << 1) - 1) || 81 tail == head) { 82 trace_pvrdma_ring_next_elem_read_no_data(ring->name); 83 return NULL; 84 } 85 86 idx = head & (ring->max_elems - 1); 87 offset = idx * ring->elem_sz; 88 return ring->pages[offset / TARGET_PAGE_SIZE] + (offset % TARGET_PAGE_SIZE); 89 } 90 91 void pvrdma_ring_read_inc(PvrdmaRing *ring) 92 { 93 uint32_t idx = qatomic_read(&ring->ring_state->cons_head); 94 95 idx = (idx + 1) & ((ring->max_elems << 1) - 1); 96 qatomic_set(&ring->ring_state->cons_head, idx); 97 } 98 99 void *pvrdma_ring_next_elem_write(PvrdmaRing *ring) 100 { 101 unsigned int idx, offset; 102 const uint32_t tail = qatomic_read(&ring->ring_state->prod_tail); 103 const uint32_t head = qatomic_read(&ring->ring_state->cons_head); 104 105 if (tail & ~((ring->max_elems << 1) - 1) || 106 head & ~((ring->max_elems << 1) - 1) || 107 tail == (head ^ ring->max_elems)) { 108 rdma_error_report("CQ is full"); 109 return NULL; 110 } 111 112 idx = tail & (ring->max_elems - 1); 113 offset = idx * ring->elem_sz; 114 return ring->pages[offset / TARGET_PAGE_SIZE] + (offset % TARGET_PAGE_SIZE); 115 } 116 117 void pvrdma_ring_write_inc(PvrdmaRing *ring) 118 { 119 uint32_t idx = qatomic_read(&ring->ring_state->prod_tail); 120 121 idx = (idx + 1) & ((ring->max_elems << 1) - 1); 122 qatomic_set(&ring->ring_state->prod_tail, idx); 123 } 124 125 void pvrdma_ring_free(PvrdmaRing *ring) 126 { 127 if (!ring) { 128 return; 129 } 130 131 if (!ring->pages) { 132 return; 133 } 134 135 while (ring->npages--) { 136 rdma_pci_dma_unmap(ring->dev, ring->pages[ring->npages], 137 TARGET_PAGE_SIZE); 138 } 139 140 g_free(ring->pages); 141 ring->pages = NULL; 142 } 143