vfio/common: Record DMA mapped IOVA ranges

According to the device DMA logging uAPI, IOVA ranges to be logged by
the device must be provided all at once upon DMA logging start.

As preparation for the following patches which will add device dirty
page tracking, keep a record of all DMA mapped IOVA ranges so later they
can be used for DMA logging start.

Signed-off-by: Avihai Horon <avihaih@nvidia.com>
Signed-off-by: Joao Martins <joao.m.martins@oracle.com>
Reviewed-by: Cédric Le Goater <clg@redhat.com>
Link: https://lore.kernel.org/r/20230307125450.62409-10-joao.m.martins@oracle.com
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>

1 files changed, 85 insertions, 0 deletions

diff --git a/hw/vfio/common.c b/hw/vfio/common.c
index 63831eab78..811502dbc9 100644
--- a/hw/vfio/common.c
+++ b/hw/vfio/common.c
@@ -1325,11 +1325,96 @@ static int vfio_set_dirty_page_tracking(VFIOContainer *container, bool start)
     return ret;
 }
 
+typedef struct VFIODirtyRanges {
+    hwaddr min32;
+    hwaddr max32;
+    hwaddr min64;
+    hwaddr max64;
+} VFIODirtyRanges;
+
+typedef struct VFIODirtyRangesListener {
+    VFIOContainer *container;
+    VFIODirtyRanges ranges;
+    MemoryListener listener;
+} VFIODirtyRangesListener;
+
+static void vfio_dirty_tracking_update(MemoryListener *listener,
+                                       MemoryRegionSection *section)
+{
+    VFIODirtyRangesListener *dirty = container_of(listener,
+                                                  VFIODirtyRangesListener,
+                                                  listener);
+    VFIODirtyRanges *range = &dirty->ranges;
+    hwaddr iova, end, *min, *max;
+
+    if (!vfio_listener_valid_section(section, "tracking_update") ||
+        !vfio_get_section_iova_range(dirty->container, section,
+                                     &iova, &end, NULL)) {
+        return;
+    }
+
+    /*
+     * The address space passed to the dirty tracker is reduced to two ranges:
+     * one for 32-bit DMA ranges, and another one for 64-bit DMA ranges.
+     * The underlying reports of dirty will query a sub-interval of each of
+     * these ranges.
+     *
+     * The purpose of the dual range handling is to handle known cases of big
+     * holes in the address space, like the x86 AMD 1T hole. The alternative
+     * would be an IOVATree but that has a much bigger runtime overhead and
+     * unnecessary complexity.
+     */
+    min = (end <= UINT32_MAX) ? &range->min32 : &range->min64;
+    max = (end <= UINT32_MAX) ? &range->max32 : &range->max64;
+
+    if (*min > iova) {
+        *min = iova;
+    }
+    if (*max < end) {
+        *max = end;
+    }
+
+    trace_vfio_device_dirty_tracking_update(iova, end, *min, *max);
+    return;
+}
+
+static const MemoryListener vfio_dirty_tracking_listener = {
+    .name = "vfio-tracking",
+    .region_add = vfio_dirty_tracking_update,
+};
+
+static void vfio_dirty_tracking_init(VFIOContainer *container,
+                                     VFIODirtyRanges *ranges)
+{
+    VFIODirtyRangesListener dirty;
+
+    memset(&dirty, 0, sizeof(dirty));
+    dirty.ranges.min32 = UINT32_MAX;
+    dirty.ranges.min64 = UINT64_MAX;
+    dirty.listener = vfio_dirty_tracking_listener;
+    dirty.container = container;
+
+    memory_listener_register(&dirty.listener,
+                             container->space->as);
+
+    *ranges = dirty.ranges;
+
+    /*
+     * The memory listener is synchronous, and used to calculate the range
+     * to dirty tracking. Unregister it after we are done as we are not
+     * interested in any follow-up updates.
+     */
+    memory_listener_unregister(&dirty.listener);
+}
+
 static void vfio_listener_log_global_start(MemoryListener *listener)
 {
     VFIOContainer *container = container_of(listener, VFIOContainer, listener);
+    VFIODirtyRanges ranges;
     int ret;
 
+    vfio_dirty_tracking_init(container, &ranges);
+
     ret = vfio_set_dirty_page_tracking(container, true);
     if (ret) {
         vfio_set_migration_error(ret);