vkr: scope down FORCE_ENABLE_DMABUF

1. the workaround is only required for host visible mem type
2. remove the def FORCE_ENABLE_DMABUF from common
3. update the docs to reflect the current assumptions
4. sanity check memory export before forcing export, which requires
   extensions to be initialized before memory properties init for a
   physical device

Signed-off-by: Yiwei Zhang <zzyiwei@chromium.org>
Reviewed-by: Chia-I Wu <olvaffe@gmail.com>

src/venus/vkr_common.h

@@ -33,16 +33,6 @@
 
 #include "vkr_renderer.h"
 
-/*
- * TODO what extensions do we need from the host driver?
- *
- * We don't check vkGetPhysicalDeviceExternalBufferProperties, etc. yet.  Even
- * if we did, silently adding external memory info to vkCreateBuffer or
- * vkCreateImage could change the results of vkGetBufferMemoryRequirements or
- * vkGetImageMemoryRequirements and confuse the guest.
- */
-#define FORCE_ENABLE_DMABUF
-
 #define VKR_DEBUG(category) (unlikely(vkr_debug_flags & VKR_DEBUG_##category))
 
 /* define a type-safe cast function */

src/venus/vkr_device_memory.c

@@ -82,7 +82,8 @@ vkr_dispatch_vkAllocateMemory(struct vn_dispatch_context *dispatch,
    VkBaseInStructure *prev_of_res_info = NULL;
    VkImportMemoryResourceInfoMESA *res_info = NULL;
    VkImportMemoryFdInfoKHR local_import_info = { .fd = -1 };
-   VkExportMemoryAllocateInfo *export_info = NULL;
+   VkExportMemoryAllocateInfo *export_info = vkr_find_struct(
+      args->pAllocateInfo->pNext, VK_STRUCTURE_TYPE_EXPORT_MEMORY_ALLOCATE_INFO);
    struct vkr_device_memory *mem = NULL;
    const uint32_t mem_type_index = args->pAllocateInfo->memoryTypeIndex;
    const uint32_t property_flags =
@@ -103,12 +104,19 @@ vkr_dispatch_vkAllocateMemory(struct vn_dispatch_context *dispatch,
       prev_of_res_info->pNext = (const struct VkBaseInStructure *)&local_import_info;
    }
 
-   export_info = vkr_find_struct(args->pAllocateInfo->pNext,
-                                 VK_STRUCTURE_TYPE_EXPORT_MEMORY_ALLOCATE_INFO);
-
-#ifdef FORCE_ENABLE_DMABUF
+   /* XXX Force dma_buf export until:
+    * - a new extension that supports direct export from host visible memory
+    * - client capable of consuming opaque fd
+    *
+    * Most VkImage and VkBuffer are non-external while most VkDeviceMemory are external
+    * if allocated with a host visible memory type. We still violate the spec by binding
+    * external memory to non-external image or buffer, which needs spec changes with a
+    * new extension.
+    */
    VkExportMemoryAllocateInfo local_export_info;
-   if (dev->physical_device->EXT_external_memory_dma_buf) {
+   if ((property_flags & VK_MEMORY_PROPERTY_HOST_VISIBLE_BIT) &&
+       dev->physical_device->EXT_external_memory_dma_buf) {
+      if (dev->physical_device->is_memory_export_supported) {
          if (export_info) {
             export_info->handleTypes |= VK_EXTERNAL_MEMORY_HANDLE_TYPE_DMA_BUF_BIT_EXT;
          } else {
@@ -121,7 +129,7 @@ vkr_dispatch_vkAllocateMemory(struct vn_dispatch_context *dispatch,
             ((VkMemoryAllocateInfo *)args->pAllocateInfo)->pNext = &local_export_info;
          }
       }
-#endif /* FORCE_ENABLE_DMABUF */
+   }
 
    if (export_info) {
       if (export_info->handleTypes & VK_EXTERNAL_MEMORY_HANDLE_TYPE_OPAQUE_FD_BIT)

src/venus/vkr_physical_device.c

@@ -95,6 +95,31 @@ vkr_physical_device_init_memory_properties(struct vkr_physical_device *physical_
     * filter out VK_MEMORY_PROPERTY_HOST_VISIBLE_BIT here if a memory type is
     * not always exportable.
     */
+
+   /* XXX is_memory_export_supported needs to be filled with a new extension
+    * which supports query fd export against the raw memory types. Currently,
+    * we workaround by checking external buffer properties before forcing
+    * enable dma_buf path of device memory allocation.
+    */
+   if (!physical_dev->EXT_external_memory_dma_buf)
+      return;
+
+   const VkPhysicalDeviceExternalBufferInfo info = {
+      .sType = VK_STRUCTURE_TYPE_PHYSICAL_DEVICE_EXTERNAL_BUFFER_INFO,
+      .usage = VK_BUFFER_USAGE_TRANSFER_SRC_BIT,
+      .handleType = VK_EXTERNAL_MEMORY_HANDLE_TYPE_DMA_BUF_BIT_EXT,
+   };
+   VkExternalBufferProperties props = {
+      .sType = VK_STRUCTURE_TYPE_EXTERNAL_BUFFER_PROPERTIES,
+   };
+   vkGetPhysicalDeviceExternalBufferProperties(handle, &info, &props);
+   physical_dev->is_memory_export_supported =
+      (props.externalMemoryProperties.externalMemoryFeatures &
+       VK_EXTERNAL_MEMORY_FEATURE_EXPORTABLE_BIT) &&
+      (props.externalMemoryProperties.exportFromImportedHandleTypes &
+       VK_EXTERNAL_MEMORY_HANDLE_TYPE_OPAQUE_FD_BIT) &&
+      (props.externalMemoryProperties.exportFromImportedHandleTypes &
+       VK_EXTERNAL_MEMORY_HANDLE_TYPE_DMA_BUF_BIT_EXT);
 }
 
 static void

src/venus/vkr_physical_device.h

@@ -23,6 +23,7 @@ struct vkr_physical_device {
    bool KHR_external_fence_fd;
 
    VkPhysicalDeviceMemoryProperties memory_properties;
+   bool is_memory_export_supported;
 
    struct list_head devices;
 };