hw/rdma/vmw/pvrdma_dev_ring.c

   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 "hw/pci/pci.h"
  18 #include "cpu.h"
  19 #include "qemu/cutils.h"
  20
  21 #include "trace.h"
  22
  23 #include "../rdma_utils.h"
  24 #include "pvrdma_dev_ring.h"
  25
  26 int pvrdma_ring_init(PvrdmaRing *ring, const char *name, PCIDevice *dev,
  27                      PvrdmaRingState *ring_state, uint32_t max_elems,
  28                      size_t elem_sz, dma_addr_t *tbl, uint32_t npages)
  29 {
  30     int i;
  31     int rc = 0;
  32
  33     pstrcpy(ring->name, MAX_RING_NAME_SZ, name);
  34     ring->dev = dev;
  35     ring->ring_state = ring_state;
  36     ring->max_elems = max_elems;
  37     ring->elem_sz = elem_sz;
  38     /* TODO: Give a moment to think if we want to redo driver settings
  39     qatomic_set(&ring->ring_state->prod_tail, 0);
  40     qatomic_set(&ring->ring_state->cons_head, 0);
  41     */
  42     ring->npages = npages;
  43     ring->pages = g_new0(void *, npages);
  44
  45     for (i = 0; i < npages; i++) {
  46         if (!tbl[i]) {
  47             rdma_error_report("npages=%d but tbl[%d] is NULL", npages, i);
  48             continue;
  49         }
  50
  51         ring->pages[i] = rdma_pci_dma_map(dev, tbl[i], TARGET_PAGE_SIZE);
  52         if (!ring->pages[i]) {
  53             rc = -ENOMEM;
  54             rdma_error_report("Failed to map to page %d in ring %s", i, name);
  55             goto out_free;
  56         }
  57         memset(ring->pages[i], 0, TARGET_PAGE_SIZE);
  58     }
  59
  60     goto out;
  61
  62 out_free:
  63     while (i--) {
  64         rdma_pci_dma_unmap(dev, ring->pages[i], TARGET_PAGE_SIZE);
  65     }
  66     g_free(ring->pages);
  67
  68 out:
  69     return rc;
  70 }
  71
  72 void *pvrdma_ring_next_elem_read(PvrdmaRing *ring)
  73 {
  74     unsigned int idx, offset;
  75     const uint32_t tail = qatomic_read(&ring->ring_state->prod_tail);
  76     const uint32_t head = qatomic_read(&ring->ring_state->cons_head);
  77
  78     if (tail & ~((ring->max_elems << 1) - 1) ||
  79         head & ~((ring->max_elems << 1) - 1) ||
  80         tail == head) {
  81         trace_pvrdma_ring_next_elem_read_no_data(ring->name);
  82         return NULL;
  83     }
  84
  85     idx = head & (ring->max_elems - 1);
  86     offset = idx * ring->elem_sz;
  87     return ring->pages[offset / TARGET_PAGE_SIZE] + (offset % TARGET_PAGE_SIZE);
  88 }
  89
  90 void pvrdma_ring_read_inc(PvrdmaRing *ring)
  91 {
  92     uint32_t idx = qatomic_read(&ring->ring_state->cons_head);
  93
  94     idx = (idx + 1) & ((ring->max_elems << 1) - 1);
  95     qatomic_set(&ring->ring_state->cons_head, idx);
  96 }
  97
  98 void *pvrdma_ring_next_elem_write(PvrdmaRing *ring)
  99 {
 100     unsigned int idx, offset;
 101     const uint32_t tail = qatomic_read(&ring->ring_state->prod_tail);
 102     const uint32_t head = qatomic_read(&ring->ring_state->cons_head);
 103
 104     if (tail & ~((ring->max_elems << 1) - 1) ||
 105         head & ~((ring->max_elems << 1) - 1) ||
 106         tail == (head ^ ring->max_elems)) {
 107         rdma_error_report("CQ is full");
 108         return NULL;
 109     }
 110
 111     idx = tail & (ring->max_elems - 1);
 112     offset = idx * ring->elem_sz;
 113     return ring->pages[offset / TARGET_PAGE_SIZE] + (offset % TARGET_PAGE_SIZE);
 114 }
 115
 116 void pvrdma_ring_write_inc(PvrdmaRing *ring)
 117 {
 118     uint32_t idx = qatomic_read(&ring->ring_state->prod_tail);
 119
 120     idx = (idx + 1) & ((ring->max_elems << 1) - 1);
 121     qatomic_set(&ring->ring_state->prod_tail, idx);
 122 }
 123
 124 void pvrdma_ring_free(PvrdmaRing *ring)
 125 {
 126     if (!ring) {
 127         return;
 128     }
 129
 130     if (!ring->pages) {
 131         return;
 132     }
 133
 134     while (ring->npages--) {
 135         rdma_pci_dma_unmap(ring->dev, ring->pages[ring->npages],
 136                            TARGET_PAGE_SIZE);
 137     }
 138
 139     g_free(ring->pages);
 140     ring->pages = NULL;
 141 }