[Qemu-devel] [PATCH v8 11/13] vfio: Add function to get dirty page list

[Kirti Wankhede <kwankhede@nvidia.com>]

Dirty page tracking (.log_sync) is part of RAM copying state, where
vendor driver provides the bitmap of pages which are dirtied by vendor
driver through migration region and as part of RAM copy, those pages
gets copied to file stream.

To get dirty page bitmap:
- write start address, page_size and pfn count.
- read count of pfns copied. Vendor driver should take one of the below action:
    - Vendor driver should return VFIO_DEVICE_DIRTY_PFNS_NONE if driver
      doesn't have any page to report dirty in given range or rest of the range
    - Vendor driver should return VFIO_DEVICE_DIRTY_PFNS_ALL to mark all pages
      dirty for given range or rest of the range.
    - Vendor driver should return copied_pfns and provide bitmap for copied_pfn
      in migration region.
- read data_offset, where vendor driver has written bitmap.
- read bitmap from from the migration region from data_offset.
- Iterate above steps till page bitmap for all requested pfns are copied.

Signed-off-by: Kirti Wankhede <kwankhede@nvidia.com>
Reviewed-by: Neo Jia <cjia@nvidia.com>
---
 hw/vfio/migration.c           | 123 ++++++++++++++++++++++++++++++++++++++++++
 hw/vfio/trace-events          |   1 +
 include/hw/vfio/vfio-common.h |   2 +
 3 files changed, 126 insertions(+)

diff --git a/hw/vfio/migration.c b/hw/vfio/migration.c
index 765015fdc2dd..eff4b2a4a6e8 100644
--- a/hw/vfio/migration.c
+++ b/hw/vfio/migration.c
@@ -276,6 +276,129 @@ static int vfio_load_device_config_state(QEMUFile *f, void *opaque)
     return qemu_file_get_error(f);
 }
 
+void vfio_get_dirty_page_list(VFIODevice *vbasedev,
+                              uint64_t start_pfn,
+                              uint64_t pfn_count,
+                              uint64_t page_size)
+{
+    VFIOMigration *migration = vbasedev->migration;
+    VFIORegion *region = &migration->region;
+    uint64_t count = 0;
+    int64_t copied_pfns = 0;
+    int64_t total_pfns = pfn_count;
+    int ret;
+
+    qemu_mutex_lock(&migration->lock);
+
+    while (total_pfns > 0) {
+        uint64_t bitmap_size, data_offset = 0;
+        uint64_t start = start_pfn + count;
+        void *buf = NULL;
+        bool buffer_mmaped = false;
+
+        ret = pwrite(vbasedev->fd, &start, sizeof(start),
+                 region->fd_offset + offsetof(struct vfio_device_migration_info,
+                                              start_pfn));
+        if (ret < 0) {
+            error_report("%s: Failed to set dirty pages start address %d %s",
+                         vbasedev->name, ret, strerror(errno));
+            goto dpl_unlock;
+        }
+
+        ret = pwrite(vbasedev->fd, &page_size, sizeof(page_size),
+                 region->fd_offset + offsetof(struct vfio_device_migration_info,
+                                              page_size));
+        if (ret < 0) {
+            error_report("%s: Failed to set dirty page size %d %s",
+                         vbasedev->name, ret, strerror(errno));
+            goto dpl_unlock;
+        }
+
+        ret = pwrite(vbasedev->fd, &total_pfns, sizeof(total_pfns),
+                 region->fd_offset + offsetof(struct vfio_device_migration_info,
+                                              total_pfns));
+        if (ret < 0) {
+            error_report("%s: Failed to set dirty page total pfns %d %s",
+                         vbasedev->name, ret, strerror(errno));
+            goto dpl_unlock;
+        }
+
+        /* Read copied dirty pfns */
+        ret = pread(vbasedev->fd, &copied_pfns, sizeof(copied_pfns),
+                region->fd_offset + offsetof(struct vfio_device_migration_info,
+                                             copied_pfns));
+        if (ret < 0) {
+            error_report("%s: Failed to get dirty pages bitmap count %d %s",
+                         vbasedev->name, ret, strerror(errno));
+            goto dpl_unlock;
+        }
+
+        if (copied_pfns == VFIO_DEVICE_DIRTY_PFNS_NONE) {
+            /*
+             * copied_pfns could be 0 if driver doesn't have any page to
+             * report dirty in given range
+             */
+            break;
+        } else if (copied_pfns == VFIO_DEVICE_DIRTY_PFNS_ALL) {
+            /* Mark all pages dirty for this range */
+            cpu_physical_memory_set_dirty_range(start * page_size,
+                                                total_pfns * page_size,
+                                                DIRTY_MEMORY_MIGRATION);
+            break;
+        }
+
+        bitmap_size = BITS_TO_LONGS(copied_pfns) * sizeof(unsigned long);
+
+        ret = pread(vbasedev->fd, &data_offset, sizeof(data_offset),
+                region->fd_offset + offsetof(struct vfio_device_migration_info,
+                                             data_offset));
+        if (ret != sizeof(data_offset)) {
+            error_report("%s: Failed to get migration buffer data offset %d",
+                         vbasedev->name, ret);
+            goto dpl_unlock;
+        }
+
+        if (region->mmaps) {
+            buf = find_data_region(region, data_offset, bitmap_size);
+        }
+
+        buffer_mmaped = (buf != NULL) ? true : false;
+
+        if (!buffer_mmaped) {
+            buf = g_try_malloc0(bitmap_size);
+            if (!buf) {
+                error_report("%s: Error allocating buffer ", __func__);
+                goto dpl_unlock;
+            }
+
+            ret = pread(vbasedev->fd, buf, bitmap_size,
+                        region->fd_offset + data_offset);
+            if (ret != bitmap_size) {
+                error_report("%s: Failed to get dirty pages bitmap %d",
+                             vbasedev->name, ret);
+                g_free(buf);
+                goto dpl_unlock;
+            }
+        }
+
+        cpu_physical_memory_set_dirty_lebitmap((unsigned long *)buf,
+                                               start * page_size,
+                                               copied_pfns);
+        count      += copied_pfns;
+        total_pfns -= copied_pfns;
+
+        if (!buffer_mmaped) {
+            g_free(buf);
+        }
+    }
+
+    trace_vfio_get_dirty_page_list(vbasedev->name, start_pfn, pfn_count,
+                                   page_size);
+
+dpl_unlock:
+    qemu_mutex_unlock(&migration->lock);
+}
+
 /* ---------------------------------------------------------------------- */
 
 static int vfio_save_setup(QEMUFile *f, void *opaque)
diff --git a/hw/vfio/trace-events b/hw/vfio/trace-events
index ac065b559f4e..414a5e69ec5e 100644
--- a/hw/vfio/trace-events
+++ b/hw/vfio/trace-events
@@ -160,3 +160,4 @@ vfio_save_complete_precopy(char *name) " (%s)"
 vfio_load_device_config_state(char *name) " (%s)"
 vfio_load_state(char *name, uint64_t data) " (%s) data 0x%"PRIx64
 vfio_load_state_device_data(char *name, uint64_t data_offset, uint64_t data_size) " (%s) Offset 0x%"PRIx64" size 0x%"PRIx64
+vfio_get_dirty_page_list(char *name, uint64_t start, uint64_t pfn_count, uint64_t page_size) " (%s) start 0x%"PRIx64" pfn_count 0x%"PRIx64 " page size 0x%"PRIx64
diff --git a/include/hw/vfio/vfio-common.h b/include/hw/vfio/vfio-common.h
index dcab8a4ae0f9..41ff5ebba27d 100644
--- a/include/hw/vfio/vfio-common.h
+++ b/include/hw/vfio/vfio-common.h
@@ -219,5 +219,7 @@ int vfio_spapr_remove_window(VFIOContainer *container,
 
 int vfio_migration_probe(VFIODevice *vbasedev, Error **errp);
 void vfio_migration_finalize(VFIODevice *vbasedev);
+void vfio_get_dirty_page_list(VFIODevice *vbasedev, uint64_t start_pfn,
+                               uint64_t pfn_count, uint64_t page_size);
 
 #endif /* HW_VFIO_VFIO_COMMON_H */
-- 
2.7.0