nvk: Add external memory queries

Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/24326>

src/nouveau/vulkan/nvk_buffer.c

@@ -64,6 +64,50 @@ nvk_GetDeviceBufferMemoryRequirements(VkDevice _device,
    }
 }
 
+VKAPI_ATTR void VKAPI_CALL
+nvk_GetPhysicalDeviceExternalBufferProperties(
+   VkPhysicalDevice physicalDevice,
+   const VkPhysicalDeviceExternalBufferInfo *pExternalBufferInfo,
+   VkExternalBufferProperties *pExternalBufferProperties)
+{
+   /* The Vulkan 1.3.256 spec says:
+    *
+    *    VUID-VkPhysicalDeviceExternalBufferInfo-handleType-parameter
+    *
+    *    "handleType must be a valid VkExternalMemoryHandleTypeFlagBits value"
+    *
+    * This differs from VkPhysicalDeviceExternalImageFormatInfo, which
+    * surprisingly permits handleType == 0.
+    */
+   assert(pExternalBufferInfo->handleType != 0);
+
+   /* All of the current flags are for sparse which we don't support yet.
+    * Even when we do support it, doing sparse on external memory sounds
+    * sketchy.  Also, just disallowing flags is the safe option.
+    */
+   if (pExternalBufferInfo->flags)
+      goto unsupported;
+
+   switch (pExternalBufferInfo->handleType) {
+   case VK_EXTERNAL_MEMORY_HANDLE_TYPE_OPAQUE_FD_BIT:
+   case VK_EXTERNAL_MEMORY_HANDLE_TYPE_DMA_BUF_BIT_EXT:
+      pExternalBufferProperties->externalMemoryProperties = nvk_dma_buf_mem_props;
+      return;
+   default:
+      goto unsupported;
+   }
+
+unsupported:
+   /* From the Vulkan 1.3.256 spec:
+    *
+    *    compatibleHandleTypes must include at least handleType.
+    */
+   pExternalBufferProperties->externalMemoryProperties =
+      (VkExternalMemoryProperties) {
+         .compatibleHandleTypes = pExternalBufferInfo->handleType,
+      };
+}
+
 VKAPI_ATTR VkResult VKAPI_CALL
 nvk_BindBufferMemory2(VkDevice _device,
                       uint32_t bindInfoCount,