[PATCH v4 08/14] vfio/common: Record DMA mapped IOVA ranges

[Joao Martins]

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>
---
 hw/vfio/common.c              | 76 +++++++++++++++++++++++++++++++++++
 hw/vfio/trace-events          |  1 +
 include/hw/vfio/vfio-common.h | 13 ++++++
 3 files changed, 90 insertions(+)

diff --git a/hw/vfio/common.c b/hw/vfio/common.c
index 3a6491dbc523..a9b1fc999121 100644
--- a/hw/vfio/common.c
+++ b/hw/vfio/common.c
@@ -1334,11 +1334,87 @@ static int vfio_set_dirty_page_tracking(VFIOContainer 
*container, bool start)
     return ret;
 }
 
+static void vfio_dirty_tracking_update(MemoryListener *listener,
+                                       MemoryRegionSection *section)
+{
+    VFIODirtyRanges *dirty = container_of(listener, VFIODirtyRanges, listener);
+    VFIODirtyTrackingRange *range = &dirty->ranges;
+    hwaddr max32 = UINT32_MAX - 1ULL;
+    hwaddr iova, end;
+
+    if (!vfio_listener_valid_section(section) ||
+        !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.
+     */
+    if (iova < max32 && end <= max32) {
+        if (range->min32 > iova) {
+            range->min32 = iova;
+        }
+        if (range->max32 < end) {
+            range->max32 = end;
+        }
+        trace_vfio_device_dirty_tracking_update(iova, end,
+                                    range->min32, range->max32);
+    } else {
+        if (!range->min64 || range->min64 > iova) {
+            range->min64 = iova;
+        }
+        if (range->max64 < end) {
+            range->max64 = end;
+        }
+        trace_vfio_device_dirty_tracking_update(iova, end,
+                                    range->min64, range->max64);
+    }
+
+    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 *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);
+
+    /*
+     * 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 dirty;
     int ret;
 
+    vfio_dirty_tracking_init(container, &dirty);
+
     ret = vfio_set_dirty_page_tracking(container, true);
     if (ret) {
         vfio_set_migration_error(ret);
diff --git a/hw/vfio/trace-events b/hw/vfio/trace-events
index 669d9fe07cd9..d97a6de17921 100644
--- a/hw/vfio/trace-events
+++ b/hw/vfio/trace-events
@@ -104,6 +104,7 @@ vfio_known_safe_misalignment(const char *name, uint64_t 
iova, uint64_t offset_wi
 vfio_listener_region_add_no_dma_map(const char *name, uint64_t iova, uint64_t 
size, uint64_t page_size) "Region \"%s\" 0x%"PRIx64" size=0x%"PRIx64" is not 
aligned to 0x%"PRIx64" and cannot be mapped for DMA"
 vfio_listener_region_del_skip(uint64_t start, uint64_t end) "SKIPPING 
region_del 0x%"PRIx64" - 0x%"PRIx64
 vfio_listener_region_del(uint64_t start, uint64_t end) "region_del 0x%"PRIx64" 
- 0x%"PRIx64
+vfio_device_dirty_tracking_update(uint64_t start, uint64_t end, uint64_t min, 
uint64_t max) "section 0x%"PRIx64" - 0x%"PRIx64" -> update [0x%"PRIx64" - 
0x%"PRIx64"]"
 vfio_disconnect_container(int fd) "close container->fd=%d"
 vfio_put_group(int fd) "close group->fd=%d"
 vfio_get_device(const char * name, unsigned int flags, unsigned int 
num_regions, unsigned int num_irqs) "Device %s flags: %u, regions: %u, irqs: %u"
diff --git a/include/hw/vfio/vfio-common.h b/include/hw/vfio/vfio-common.h
index 87524c64a443..0f84136cceb5 100644
--- a/include/hw/vfio/vfio-common.h
+++ b/include/hw/vfio/vfio-common.h
@@ -96,6 +96,19 @@ typedef struct VFIOContainer {
     QLIST_ENTRY(VFIOContainer) next;
 } VFIOContainer;
 
+typedef struct VFIODirtyTrackingRange {
+    hwaddr min32;
+    hwaddr max32;
+    hwaddr min64;
+    hwaddr max64;
+} VFIODirtyTrackingRange;
+
+typedef struct VFIODirtyRanges {
+    VFIOContainer *container;
+    VFIODirtyTrackingRange ranges;
+    MemoryListener listener;
+} VFIODirtyRanges;
+
 typedef struct VFIOGuestIOMMU {
     VFIOContainer *container;
     IOMMUMemoryRegion *iommu_mr;
-- 
2.17.2