[PATCH v6 8/9] vfio: Add Error** argument to .get_dirty_bitmap() handler

["Cédric Le Goater" <clg@redhat.com>]

Let the callers do the error reporting. Add documentation while at it.

Signed-off-by: Cédric Le Goater <clg@redhat.com>
---

 Changes in v6:

 - Fixed the line wrapping (Avihai)
 - Fixed query_dirty_bitmap documentation (Avihai)
   
 Changes in v5:

 - Replaced error_setg() by error_setg_errno() in
   vfio_devices_query_dirty_bitmap() and vfio_legacy_query_dirty_bitmap()
 - ':' -> '-' in vfio_iommu_map_dirty_notify()
 
 include/hw/vfio/vfio-common.h         |  4 +-
 include/hw/vfio/vfio-container-base.h | 21 +++++++--
 hw/vfio/common.c                      | 61 ++++++++++++++++++---------
 hw/vfio/container-base.c              |  7 +--
 hw/vfio/container.c                   | 14 +++---
 5 files changed, 72 insertions(+), 35 deletions(-)

diff --git a/include/hw/vfio/vfio-common.h b/include/hw/vfio/vfio-common.h
index 46f88493634b5634a9c14a5caa33a463fbf2c50d..68911d36676667352e94a97895828aff4b194b57 100644
--- a/include/hw/vfio/vfio-common.h
+++ b/include/hw/vfio/vfio-common.h
@@ -274,9 +274,9 @@ bool
 vfio_devices_all_device_dirty_tracking(const VFIOContainerBase *bcontainer);
 int vfio_devices_query_dirty_bitmap(const VFIOContainerBase *bcontainer,
                                     VFIOBitmap *vbmap, hwaddr iova,
-                                    hwaddr size);
+                                    hwaddr size, Error **errp);
 int vfio_get_dirty_bitmap(const VFIOContainerBase *bcontainer, uint64_t iova,
-                          uint64_t size, ram_addr_t ram_addr);
+                          uint64_t size, ram_addr_t ram_addr, Error **errp);
 
 /* Returns 0 on success, or a negative errno. */
 int vfio_device_get_name(VFIODevice *vbasedev, Error **errp);
diff --git a/include/hw/vfio/vfio-container-base.h b/include/hw/vfio/vfio-container-base.h
index 326ceea52a2030eec9dad289a9845866c4a8c090..42cfbf32dc737606c3f620d126f35d85d4833534 100644
--- a/include/hw/vfio/vfio-container-base.h
+++ b/include/hw/vfio/vfio-container-base.h
@@ -84,8 +84,8 @@ void vfio_container_del_section_window(VFIOContainerBase *bcontainer,
 int vfio_container_set_dirty_page_tracking(VFIOContainerBase *bcontainer,
                                            bool start, Error **errp);
 int vfio_container_query_dirty_bitmap(const VFIOContainerBase *bcontainer,
-                                      VFIOBitmap *vbmap,
-                                      hwaddr iova, hwaddr size);
+                                      VFIOBitmap *vbmap, hwaddr iova,
+                                      hwaddr size, Error **errp);
 
 void vfio_container_init(VFIOContainerBase *bcontainer,
                          VFIOAddressSpace *space,
@@ -138,9 +138,22 @@ struct VFIOIOMMUClass {
      */
     int (*set_dirty_page_tracking)(const VFIOContainerBase *bcontainer,
                                    bool start, Error **errp);
+    /**
+     * @query_dirty_bitmap
+     *
+     * Get bitmap of dirty pages from container
+     *
+     * @bcontainer: #VFIOContainerBase from which to get dirty pages
+     * @vbmap: #VFIOBitmap internal bitmap structure
+     * @iova: iova base address
+     * @size: size of iova range
+     * @errp: pointer to Error*, to store an error if it happens.
+     *
+     * Returns zero to indicate success and negative for error
+     */
     int (*query_dirty_bitmap)(const VFIOContainerBase *bcontainer,
-                              VFIOBitmap *vbmap,
-                              hwaddr iova, hwaddr size);
+                              VFIOBitmap *vbmap, hwaddr iova, hwaddr size,
+                              Error **errp);
     /* PCI specific */
     int (*pci_hot_reset)(VFIODevice *vbasedev, bool single);
 
diff --git a/hw/vfio/common.c b/hw/vfio/common.c
index 919c4c52bc1590fd6c0bda37ba5881f58ff2ffff..9b5123d45fc1f9d5be4bbbf92898f89cd11e1363 100644
--- a/hw/vfio/common.c
+++ b/hw/vfio/common.c
@@ -1140,8 +1140,8 @@ static int vfio_device_dma_logging_report(VFIODevice *vbasedev, hwaddr iova,
 }
 
 int vfio_devices_query_dirty_bitmap(const VFIOContainerBase *bcontainer,
-                                    VFIOBitmap *vbmap, hwaddr iova,
-                                    hwaddr size)
+                                    VFIOBitmap *vbmap, hwaddr iova, hwaddr size,
+                                    Error **errp)
 {
     VFIODevice *vbasedev;
     int ret;
@@ -1150,10 +1150,10 @@ int vfio_devices_query_dirty_bitmap(const VFIOContainerBase *bcontainer,
         ret = vfio_device_dma_logging_report(vbasedev, iova, size,
                                              vbmap->bitmap);
         if (ret) {
-            error_report("%s: Failed to get DMA logging report, iova: "
-                         "0x%" HWADDR_PRIx ", size: 0x%" HWADDR_PRIx
-                         ", err: %d (%s)",
-                         vbasedev->name, iova, size, ret, strerror(-ret));
+            error_setg_errno(errp, -ret,
+                             "%s: Failed to get DMA logging report, iova: "
+                             "0x%" HWADDR_PRIx ", size: 0x%" HWADDR_PRIx,
+                             vbasedev->name, iova, size);
 
             return ret;
         }
@@ -1163,7 +1163,7 @@ int vfio_devices_query_dirty_bitmap(const VFIOContainerBase *bcontainer,
 }
 
 int vfio_get_dirty_bitmap(const VFIOContainerBase *bcontainer, uint64_t iova,
-                          uint64_t size, ram_addr_t ram_addr)
+                          uint64_t size, ram_addr_t ram_addr, Error **errp)
 {
     bool all_device_dirty_tracking =
         vfio_devices_all_device_dirty_tracking(bcontainer);
@@ -1180,13 +1180,17 @@ int vfio_get_dirty_bitmap(const VFIOContainerBase *bcontainer, uint64_t iova,
 
     ret = vfio_bitmap_alloc(&vbmap, size);
     if (ret) {
+        error_setg_errno(errp, -ret,
+                         "Failed to allocate dirty tracking bitmap");
         return ret;
     }
 
     if (all_device_dirty_tracking) {
-        ret = vfio_devices_query_dirty_bitmap(bcontainer, &vbmap, iova, size);
+        ret = vfio_devices_query_dirty_bitmap(bcontainer, &vbmap, iova, size,
+                                              errp);
     } else {
-        ret = vfio_container_query_dirty_bitmap(bcontainer, &vbmap, iova, size);
+        ret = vfio_container_query_dirty_bitmap(bcontainer, &vbmap, iova, size,
+                                                errp);
     }
 
     if (ret) {
@@ -1234,12 +1238,13 @@ static void vfio_iommu_map_dirty_notify(IOMMUNotifier *n, IOMMUTLBEntry *iotlb)
     }
 
     ret = vfio_get_dirty_bitmap(bcontainer, iova, iotlb->addr_mask + 1,
-                                translated_addr);
+                                translated_addr, &local_err);
     if (ret) {
-        error_report("vfio_iommu_map_dirty_notify(%p, 0x%"HWADDR_PRIx", "
-                     "0x%"HWADDR_PRIx") = %d (%s)",
-                     bcontainer, iova, iotlb->addr_mask + 1, ret,
-                     strerror(-ret));
+        error_prepend(&local_err,
+                      "vfio_iommu_map_dirty_notify(%p, 0x%"HWADDR_PRIx", "
+                      "0x%"HWADDR_PRIx") failed - ", bcontainer, iova,
+                      iotlb->addr_mask + 1);
+        error_report_err(local_err);
     }
 
 out_unlock:
@@ -1259,12 +1264,19 @@ static int vfio_ram_discard_get_dirty_bitmap(MemoryRegionSection *section,
     const ram_addr_t ram_addr = memory_region_get_ram_addr(section->mr) +
                                 section->offset_within_region;
     VFIORamDiscardListener *vrdl = opaque;
+    Error *local_err = NULL;
+    int ret;
 
     /*
      * Sync the whole mapped region (spanning multiple individual mappings)
      * in one go.
      */
-    return vfio_get_dirty_bitmap(vrdl->bcontainer, iova, size, ram_addr);
+    ret = vfio_get_dirty_bitmap(vrdl->bcontainer, iova, size, ram_addr,
+                                &local_err);
+    if (ret) {
+        error_report_err(local_err);
+    }
+    return ret;
 }
 
 static int
@@ -1296,7 +1308,7 @@ vfio_sync_ram_discard_listener_dirty_bitmap(VFIOContainerBase *bcontainer,
 }
 
 static int vfio_sync_dirty_bitmap(VFIOContainerBase *bcontainer,
-                                  MemoryRegionSection *section)
+                                  MemoryRegionSection *section, Error **errp)
 {
     ram_addr_t ram_addr;
 
@@ -1327,7 +1339,14 @@ static int vfio_sync_dirty_bitmap(VFIOContainerBase *bcontainer,
         }
         return 0;
     } else if (memory_region_has_ram_discard_manager(section->mr)) {
-        return vfio_sync_ram_discard_listener_dirty_bitmap(bcontainer, section);
+        int ret;
+
+        ret = vfio_sync_ram_discard_listener_dirty_bitmap(bcontainer, section);
+        if (ret) {
+            error_setg(errp,
+                       "Failed to sync dirty bitmap with RAM discard listener");
+            return ret;
+        }
     }
 
     ram_addr = memory_region_get_ram_addr(section->mr) +
@@ -1335,7 +1354,7 @@ static int vfio_sync_dirty_bitmap(VFIOContainerBase *bcontainer,
 
     return vfio_get_dirty_bitmap(bcontainer,
                    REAL_HOST_PAGE_ALIGN(section->offset_within_address_space),
-                   int128_get64(section->size), ram_addr);
+                                 int128_get64(section->size), ram_addr, errp);
 }
 
 static void vfio_listener_log_sync(MemoryListener *listener,
@@ -1344,16 +1363,16 @@ static void vfio_listener_log_sync(MemoryListener *listener,
     VFIOContainerBase *bcontainer = container_of(listener, VFIOContainerBase,
                                                  listener);
     int ret;
+    Error *local_err = NULL;
 
     if (vfio_listener_skipped_section(section)) {
         return;
     }
 
     if (vfio_devices_all_dirty_tracking(bcontainer)) {
-        ret = vfio_sync_dirty_bitmap(bcontainer, section);
+        ret = vfio_sync_dirty_bitmap(bcontainer, section, &local_err);
         if (ret) {
-            error_report("vfio: Failed to sync dirty bitmap, err: %d (%s)", ret,
-                         strerror(-ret));
+            error_report_err(local_err);
             vfio_set_migration_error(ret);
         }
     }
diff --git a/hw/vfio/container-base.c b/hw/vfio/container-base.c
index 7c0764121d24b02b6c4e66e368d7dff78a6d65aa..4fa250c46fd16333d2e2358ede8b0a0afdb185b3 100644
--- a/hw/vfio/container-base.c
+++ b/hw/vfio/container-base.c
@@ -64,11 +64,12 @@ int vfio_container_set_dirty_page_tracking(VFIOContainerBase *bcontainer,
 }
 
 int vfio_container_query_dirty_bitmap(const VFIOContainerBase *bcontainer,
-                                      VFIOBitmap *vbmap,
-                                      hwaddr iova, hwaddr size)
+                                      VFIOBitmap *vbmap, hwaddr iova,
+                                      hwaddr size, Error **errp)
 {
     g_assert(bcontainer->ops->query_dirty_bitmap);
-    return bcontainer->ops->query_dirty_bitmap(bcontainer, vbmap, iova, size);
+    return bcontainer->ops->query_dirty_bitmap(bcontainer, vbmap, iova, size,
+                                               errp);
 }
 
 void vfio_container_init(VFIOContainerBase *bcontainer, VFIOAddressSpace *space,
diff --git a/hw/vfio/container.c b/hw/vfio/container.c
index c35221fbe7dc5453050f97cd186fc958e24f28f7..e00db6546c652c61a352f8e4cd65b212ecfb65bc 100644
--- a/hw/vfio/container.c
+++ b/hw/vfio/container.c
@@ -130,6 +130,7 @@ static int vfio_legacy_dma_unmap(const VFIOContainerBase *bcontainer,
     };
     bool need_dirty_sync = false;
     int ret;
+    Error *local_err = NULL;
 
     if (iotlb && vfio_devices_all_running_and_mig_active(bcontainer)) {
         if (!vfio_devices_all_device_dirty_tracking(bcontainer) &&
@@ -165,8 +166,9 @@ static int vfio_legacy_dma_unmap(const VFIOContainerBase *bcontainer,
 
     if (need_dirty_sync) {
         ret = vfio_get_dirty_bitmap(bcontainer, iova, size,
-                                    iotlb->translated_addr);
+                                    iotlb->translated_addr, &local_err);
         if (ret) {
+            error_report_err(local_err);
             return ret;
         }
     }
@@ -236,7 +238,8 @@ vfio_legacy_set_dirty_page_tracking(const VFIOContainerBase *bcontainer,
 
 static int vfio_legacy_query_dirty_bitmap(const VFIOContainerBase *bcontainer,
                                           VFIOBitmap *vbmap,
-                                          hwaddr iova, hwaddr size)
+                                          hwaddr iova, hwaddr size,
+                                          Error **errp)
 {
     const VFIOContainer *container = container_of(bcontainer, VFIOContainer,
                                                   bcontainer);
@@ -264,9 +267,10 @@ static int vfio_legacy_query_dirty_bitmap(const VFIOContainerBase *bcontainer,
     ret = ioctl(container->fd, VFIO_IOMMU_DIRTY_PAGES, dbitmap);
     if (ret) {
         ret = -errno;
-        error_report("Failed to get dirty bitmap for iova: 0x%"PRIx64
-                " size: 0x%"PRIx64" err: %d", (uint64_t)range->iova,
-                (uint64_t)range->size, errno);
+        error_setg_errno(errp, errno,
+                         "Failed to get dirty bitmap for iova: 0x%"PRIx64
+                         " size: 0x%"PRIx64, (uint64_t)range->iova,
+                         (uint64_t)range->size);
     }
 
     g_free(dbitmap);
-- 
2.45.0