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 "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 }