vhost: add traces for memory listeners

Trace these operations on two memory listeners.  It helps to verify the
new memory listener fix, and good to keep them there.

Signed-off-by: Peter Xu <peterx@redhat.com>
Message-Id: <20180122060244.29368-2-peterx@redhat.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

hw/virtio/trace-events

@@ -25,3 +25,9 @@ virtio_balloon_handle_output(const char *name, uint64_t gpa) "section name: %s g
 virtio_balloon_get_config(uint32_t num_pages, uint32_t actual) "num_pages: %d actual: %d"
 virtio_balloon_set_config(uint32_t actual, uint32_t oldactual) "actual: %d oldactual: %d"
 virtio_balloon_to_target(uint64_t target, uint32_t num_pages) "balloon target: 0x%"PRIx64" num_pages: %d"
+
+# hw/virtio/vhost.c
+vhost_region_add(void *p, const char *mr) "dev %p mr %s"
+vhost_region_del(void *p, const char *mr) "dev %p mr %s"
+vhost_iommu_region_add(void *p, const char *mr) "dev %p mr %s"
+vhost_iommu_region_del(void *p, const char *mr) "dev %p mr %s"

hw/virtio/vhost.c

@@ -27,6 +27,7 @@
 #include "hw/virtio/virtio-access.h"
 #include "migration/blocker.h"
 #include "sysemu/dma.h"
+#include "trace.h"
 
 /* enabled until disconnected backend stabilizes */
 #define _VHOST_DEBUG 1
@@ -687,6 +688,7 @@ static void vhost_region_add(MemoryListener *listener,
         return;
     }
 
+    trace_vhost_region_add(dev, section->mr->name ?: NULL);
     ++dev->n_mem_sections;
     dev->mem_sections = g_renew(MemoryRegionSection, dev->mem_sections,
                                 dev->n_mem_sections);
@@ -706,6 +708,7 @@ static void vhost_region_del(MemoryListener *listener,
         return;
     }
 
+    trace_vhost_region_del(dev, section->mr->name ?: NULL);
     vhost_set_memory(listener, section, false);
     memory_region_unref(section->mr);
     for (i = 0; i < dev->n_mem_sections; ++i) {
@@ -743,6 +746,8 @@ static void vhost_iommu_region_add(MemoryListener *listener,
         return;
     }
 
+    trace_vhost_iommu_region_add(dev, section->mr->name ?: NULL);
+
     iommu = g_malloc0(sizeof(*iommu));
     end = int128_add(int128_make64(section->offset_within_region),
                      section->size);
@@ -771,6 +776,8 @@ static void vhost_iommu_region_del(MemoryListener *listener,
         return;
     }
 
+    trace_vhost_iommu_region_del(dev, section->mr->name ?: NULL);
+
     QLIST_FOREACH(iommu, &dev->iommu_list, iommu_next) {
         if (iommu->mr == section->mr &&
             iommu->n.start == section->offset_within_region) {