hw/dataplane/hostmem.c

   1 /*
   2  * Thread-safe guest to host memory mapping
   3  *
   4  * Copyright 2012 Red Hat, Inc. and/or its affiliates
   5  *
   6  * Authors:
   7  *   Stefan Hajnoczi <stefanha@redhat.com>
   8  *
   9  * This work is licensed under the terms of the GNU GPL, version 2 or later.
  10  * See the COPYING file in the top-level directory.
  11  *
  12  */
  13
  14 #include "exec/address-spaces.h"
  15 #include "hw/virtio/dataplane/hostmem.h"
  16
  17 static int hostmem_lookup_cmp(const void *phys_, const void *region_)
  18 {
  19     hwaddr phys = *(const hwaddr *)phys_;
  20     const HostMemRegion *region = region_;
  21
  22     if (phys < region->guest_addr) {
  23         return -1;
  24     } else if (phys >= region->guest_addr + region->size) {
  25         return 1;
  26     } else {
  27         return 0;
  28     }
  29 }
  30
  31 /**
  32  * Map guest physical address to host pointer
  33  */
  34 void *hostmem_lookup(HostMem *hostmem, hwaddr phys, hwaddr len, bool is_write)
  35 {
  36     HostMemRegion *region;
  37     void *host_addr = NULL;
  38     hwaddr offset_within_region;
  39
  40     qemu_mutex_lock(&hostmem->current_regions_lock);
  41     region = bsearch(&phys, hostmem->current_regions,
  42                      hostmem->num_current_regions,
  43                      sizeof(hostmem->current_regions[0]),
  44                      hostmem_lookup_cmp);
  45     if (!region) {
  46         goto out;
  47     }
  48     if (is_write && region->readonly) {
  49         goto out;
  50     }
  51     offset_within_region = phys - region->guest_addr;
  52     if (len <= region->size - offset_within_region) {
  53         host_addr = region->host_addr + offset_within_region;
  54     }
  55 out:
  56     qemu_mutex_unlock(&hostmem->current_regions_lock);
  57
  58     return host_addr;
  59 }
  60
  61 /**
  62  * Install new regions list
  63  */
  64 static void hostmem_listener_commit(MemoryListener *listener)
  65 {
  66     HostMem *hostmem = container_of(listener, HostMem, listener);
  67
  68     qemu_mutex_lock(&hostmem->current_regions_lock);
  69     g_free(hostmem->current_regions);
  70     hostmem->current_regions = hostmem->new_regions;
  71     hostmem->num_current_regions = hostmem->num_new_regions;
  72     qemu_mutex_unlock(&hostmem->current_regions_lock);
  73
  74     /* Reset new regions list */
  75     hostmem->new_regions = NULL;
  76     hostmem->num_new_regions = 0;
  77 }
  78
  79 /**
  80  * Add a MemoryRegionSection to the new regions list
  81  */
  82 static void hostmem_append_new_region(HostMem *hostmem,
  83                                       MemoryRegionSection *section)
  84 {
  85     void *ram_ptr = memory_region_get_ram_ptr(section->mr);
  86     size_t num = hostmem->num_new_regions;
  87     size_t new_size = (num + 1) * sizeof(hostmem->new_regions[0]);
  88
  89     hostmem->new_regions = g_realloc(hostmem->new_regions, new_size);
  90     hostmem->new_regions[num] = (HostMemRegion){
  91         .host_addr = ram_ptr + section->offset_within_region,
  92         .guest_addr = section->offset_within_address_space,
  93         .size = section->size,
  94         .readonly = section->readonly,
  95     };
  96     hostmem->num_new_regions++;
  97 }
  98
  99 static void hostmem_listener_append_region(MemoryListener *listener,
 100                                            MemoryRegionSection *section)
 101 {
 102     HostMem *hostmem = container_of(listener, HostMem, listener);
 103
 104     /* Ignore non-RAM regions, we may not be able to map them */
 105     if (!memory_region_is_ram(section->mr)) {
 106         return;
 107     }
 108
 109     /* Ignore regions with dirty logging, we cannot mark them dirty */
 110     if (memory_region_is_logging(section->mr)) {
 111         return;
 112     }
 113
 114     hostmem_append_new_region(hostmem, section);
 115 }
 116
 117 /* We don't implement most MemoryListener callbacks, use these nop stubs */
 118 static void hostmem_listener_dummy(MemoryListener *listener)
 119 {
 120 }
 121
 122 static void hostmem_listener_section_dummy(MemoryListener *listener,
 123                                            MemoryRegionSection *section)
 124 {
 125 }
 126
 127 static void hostmem_listener_eventfd_dummy(MemoryListener *listener,
 128                                            MemoryRegionSection *section,
 129                                            bool match_data, uint64_t data,
 130                                            EventNotifier *e)
 131 {
 132 }
 133
 134 static void hostmem_listener_coalesced_mmio_dummy(MemoryListener *listener,
 135                                                   MemoryRegionSection *section,
 136                                                   hwaddr addr, hwaddr len)
 137 {
 138 }
 139
 140 void hostmem_init(HostMem *hostmem)
 141 {
 142     memset(hostmem, 0, sizeof(*hostmem));
 143
 144     qemu_mutex_init(&hostmem->current_regions_lock);
 145
 146     hostmem->listener = (MemoryListener){
 147         .begin = hostmem_listener_dummy,
 148         .commit = hostmem_listener_commit,
 149         .region_add = hostmem_listener_append_region,
 150         .region_del = hostmem_listener_section_dummy,
 151         .region_nop = hostmem_listener_append_region,
 152         .log_start = hostmem_listener_section_dummy,
 153         .log_stop = hostmem_listener_section_dummy,
 154         .log_sync = hostmem_listener_section_dummy,
 155         .log_global_start = hostmem_listener_dummy,
 156         .log_global_stop = hostmem_listener_dummy,
 157         .eventfd_add = hostmem_listener_eventfd_dummy,
 158         .eventfd_del = hostmem_listener_eventfd_dummy,
 159         .coalesced_mmio_add = hostmem_listener_coalesced_mmio_dummy,
 160         .coalesced_mmio_del = hostmem_listener_coalesced_mmio_dummy,
 161         .priority = 10,
 162     };
 163
 164     memory_listener_register(&hostmem->listener, &address_space_memory);
 165     if (hostmem->num_new_regions > 0) {
 166         hostmem_listener_commit(&hostmem->listener);
 167     }
 168 }
 169
 170 void hostmem_finalize(HostMem *hostmem)
 171 {
 172     memory_listener_unregister(&hostmem->listener);
 173     g_free(hostmem->new_regions);
 174     g_free(hostmem->current_regions);
 175     qemu_mutex_destroy(&hostmem->current_regions_lock);
 176 }