[RFC PATCH 1/2] hw/vfio: add a 'disablable' flag to sparse mmaped region

[Yan Zhao <yan.y.zhao@intel.com>]

add a 'disablable' flag to each each sparse mmaped region and this flag is by
default off.

vfio_region_disablable_mmaps_set_enabled() will enable/disable mmapped
subregions if its 'disablable' flag is on.

Cc: Kevin Tian <kevin.tian@intel.com>
Signed-off-by: Yan Zhao <yan.y.zhao@intel.com>
---
 hw/vfio/common.c              | 28 +++++++++++++++++++++++++++-
 hw/vfio/trace-events          |  3 ++-
 include/hw/vfio/vfio-common.h |  2 ++
 linux-headers/linux/vfio.h    |  2 ++
 4 files changed, 33 insertions(+), 2 deletions(-)

diff --git a/hw/vfio/common.c b/hw/vfio/common.c
index 6f36b02e3e..79f694dd19 100644
--- a/hw/vfio/common.c
+++ b/hw/vfio/common.c
@@ -883,11 +883,13 @@ static int vfio_setup_region_sparse_mmaps(VFIORegion *region,
     for (i = 0, j = 0; i < sparse->nr_areas; i++) {
         trace_vfio_region_sparse_mmap_entry(i, sparse->areas[i].offset,
                                             sparse->areas[i].offset +
-                                            sparse->areas[i].size);
+                                            sparse->areas[i].size,
+                                            sparse->areas[i].disablable);
 
         if (sparse->areas[i].size) {
             region->mmaps[j].offset = sparse->areas[i].offset;
             region->mmaps[j].size = sparse->areas[i].size;
+            region->mmaps[j].disablable = sparse->areas[i].disablable;
             j++;
         }
     }
@@ -1084,6 +1086,30 @@ void vfio_region_mmaps_set_enabled(VFIORegion *region, bool enabled)
                                         enabled);
 }
 
+/**
+ * enable/disable vfio regions with mmaped subregions
+ * It only disable mmapped subregions with disablable flag on
+ */
+void vfio_region_disablable_mmaps_set_enabled(VFIORegion *region, bool enabled)
+{
+    int i;
+
+    if (!region->mem) {
+        return;
+    }
+
+    for (i = 0; i < region->nr_mmaps; i++) {
+        if (region->mmaps[i].mmap && region->mmaps[i].disablable) {
+            memory_region_set_enabled(&region->mmaps[i].mem, enabled);
+            trace_vfio_region_disablable_mmaps_set_enabled(
+                    memory_region_name(region->mem),
+                    region->mmaps[i].offset,
+                    region->mmaps[i].offset + region->mmaps[i].size,
+                    enabled);
+        }
+    }
+}
+
 void vfio_reset_handler(void *opaque)
 {
     VFIOGroup *group;
diff --git a/hw/vfio/trace-events b/hw/vfio/trace-events
index 414a5e69ec..7b2d07529e 100644
--- a/hw/vfio/trace-events
+++ b/hw/vfio/trace-events
@@ -113,7 +113,7 @@ vfio_region_finalize(const char *name, int index) "Device %s, region %d"
 vfio_region_mmaps_set_enabled(const char *name, bool enabled) "Region %s mmaps enabled: %d"
 vfio_region_unmap(const char *name, unsigned long offset, unsigned long end) "Region %s unmap [0x%lx - 0x%lx]"
 vfio_region_sparse_mmap_header(const char *name, int index, int nr_areas) "Device %s region %d: %d sparse mmap entries"
-vfio_region_sparse_mmap_entry(int i, unsigned long start, unsigned long end) "sparse entry %d [0x%lx - 0x%lx]"
+vfio_region_sparse_mmap_entry(int i, unsigned long start, unsigned long end, bool disablable) "sparse entry %d [0x%lx - 0x%lx] disablable %d"
 vfio_get_dev_region(const char *name, int index, uint32_t type, uint32_t subtype) "%s index %d, %08x/%0x8"
 vfio_dma_unmap_overflow_workaround(void) ""
 
@@ -161,3 +161,4 @@ 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
+vfio_region_disablable_mmaps_set_enabled(const char *name, unsigned long offset, unsigned long end, bool enabled) "Region %s mmaps [0x%lx - 0x%lx] set to %d"
diff --git a/include/hw/vfio/vfio-common.h b/include/hw/vfio/vfio-common.h
index 41ff5ebba2..8cfe46c681 100644
--- a/include/hw/vfio/vfio-common.h
+++ b/include/hw/vfio/vfio-common.h
@@ -45,6 +45,7 @@ typedef struct VFIOMmap {
     void *mmap;
     off_t offset;
     size_t size;
+    bool disablable; /* whether this region is able to get diabled */
 } VFIOMmap;
 
 typedef struct VFIORegion {
@@ -187,6 +188,7 @@ int vfio_region_setup(Object *obj, VFIODevice *vbasedev, VFIORegion *region,
                       int index, const char *name);
 int vfio_region_mmap(VFIORegion *region);
 void vfio_region_mmaps_set_enabled(VFIORegion *region, bool enabled);
+void vfio_region_disablable_mmaps_set_enabled(VFIORegion *region, bool enabled);
 void vfio_region_unmap(VFIORegion *region);
 void vfio_region_exit(VFIORegion *region);
 void vfio_region_finalize(VFIORegion *region);
diff --git a/linux-headers/linux/vfio.h b/linux-headers/linux/vfio.h
index 4bc0236b08..f9f0ea8eda 100644
--- a/linux-headers/linux/vfio.h
+++ b/linux-headers/linux/vfio.h
@@ -258,6 +258,8 @@ struct vfio_region_info {
 struct vfio_region_sparse_mmap_area {
 	__u64	offset;	/* Offset of mmap'able area within region */
 	__u64	size;	/* Size of mmap'able area */
+	__u32   disablable; /* whether this mmap'able are able to
+					be dynamically disbled */
 };
 
 struct vfio_region_info_cap_sparse_mmap {
-- 
2.17.1