From fa8cf5026365ef9f9ddaf1bdddfb91f4a7cef968 Mon Sep 17 00:00:00 2001
From: Philip Rebohle <philip.rebohle@tu-dortmund.de>
Date: Thu, 16 Mar 2023 13:36:47 +0100
Subject: [PATCH] [dxvk] Implement functionality to import foreign buffers

---
 src/dxvk/dxvk_buffer.cpp  | 26 ++++++++++++++++++++++++++
 src/dxvk/dxvk_buffer.h    | 35 +++++++++++++++++++++++++++++++++--
 src/dxvk/dxvk_context.cpp |  4 ++++
 3 files changed, 63 insertions(+), 2 deletions(-)

diff --git a/src/dxvk/dxvk_buffer.cpp b/src/dxvk/dxvk_buffer.cpp
index f2fbf5c5..4fd2a263 100644
--- a/src/dxvk/dxvk_buffer.cpp
+++ b/src/dxvk/dxvk_buffer.cpp
@@ -62,9 +62,35 @@ namespace dxvk {
   }
 
 
+  DxvkBuffer::DxvkBuffer(
+          DxvkDevice*           device,
+    const DxvkBufferCreateInfo& createInfo,
+    const DxvkBufferImportInfo& importInfo,
+          VkMemoryPropertyFlags memFlags)
+  : m_vkd           (device->vkd()),
+    m_info          (createInfo),
+    m_import        (importInfo),
+    m_memAlloc      (nullptr),
+    m_memFlags      (memFlags),
+    m_shaderStages  (util::shaderStages(createInfo.stages)) {
+    m_physSliceLength = createInfo.size;
+    m_physSliceStride = createInfo.size;
+    m_physSliceCount  = 1;
+    m_physSliceMaxCount = 1;
+
+    m_physSlice.handle = importInfo.buffer;
+    m_physSlice.offset = importInfo.offset;
+    m_physSlice.length = createInfo.size;
+    m_physSlice.mapPtr = importInfo.mapPtr;
+
+    m_lazyAlloc = false;
+  }
+
+
   DxvkBuffer::~DxvkBuffer() {
     for (const auto& buffer : m_buffers)
       m_vkd->vkDestroyBuffer(m_vkd->device(), buffer.buffer, nullptr);
+
     m_vkd->vkDestroyBuffer(m_vkd->device(), m_buffer.buffer, nullptr);
   }
   
diff --git a/src/dxvk/dxvk_buffer.h b/src/dxvk/dxvk_buffer.h
index a82fbd0e..5be99406 100644
--- a/src/dxvk/dxvk_buffer.h
+++ b/src/dxvk/dxvk_buffer.h
@@ -55,6 +55,22 @@ namespace dxvk {
   };
 
 
+  /**
+   * \brief Buffer import info
+   *
+   * Used to import an existing Vulkan buffer. Note
+   * that imported buffers must not be renamed.
+   */
+  struct DxvkBufferImportInfo {
+    /// Buffer handle
+    VkBuffer buffer = VK_NULL_HANDLE;
+    /// Buffer offset
+    VkDeviceSize offset = 0;
+    /// Pointer to mapped memory region
+    void* mapPtr = nullptr;
+  };
+
+  
   /**
    * \brief Buffer info
    * 
@@ -95,7 +111,7 @@ namespace dxvk {
     }
   };
 
-  
+
   /**
    * \brief Virtual buffer resource
    * 
@@ -112,7 +128,13 @@ namespace dxvk {
       const DxvkBufferCreateInfo& createInfo,
             DxvkMemoryAllocator&  memAlloc,
             VkMemoryPropertyFlags memFlags);
-    
+
+    DxvkBuffer(
+            DxvkDevice*           device,
+      const DxvkBufferCreateInfo& createInfo,
+      const DxvkBufferImportInfo& importInfo,
+            VkMemoryPropertyFlags memFlags);
+
     ~DxvkBuffer();
     
     /**
@@ -294,10 +316,19 @@ namespace dxvk {
       m_nextSlices.push_back(slice);
     }
 
+    /**
+     * \brief Checks whether the buffer is imported
+     * \returns \c true if the buffer is imported
+     */
+    bool isForeign() const {
+      return m_import.buffer != VK_NULL_HANDLE;
+    }
+
   private:
 
     Rc<vk::DeviceFn>        m_vkd;
     DxvkBufferCreateInfo    m_info;
+    DxvkBufferImportInfo    m_import;
     DxvkMemoryAllocator*    m_memAlloc;
     VkMemoryPropertyFlags   m_memFlags;
     VkShaderStageFlags      m_shaderStages;
diff --git a/src/dxvk/dxvk_context.cpp b/src/dxvk/dxvk_context.cpp
index dce568a5..18138b4b 100644
--- a/src/dxvk/dxvk_context.cpp
+++ b/src/dxvk/dxvk_context.cpp
@@ -6155,6 +6155,10 @@ namespace dxvk {
     if (buffer->info().flags & VK_BUFFER_CREATE_SPARSE_BINDING_BIT)
       return false;
 
+    // Don't discard imported buffers
+    if (buffer->isForeign())
+      return false;
+
     // Suspend the current render pass if transform feedback is active prior to
     // invalidating the buffer, since otherwise we may invalidate a bound buffer.
     if ((buffer->info().usage & VK_BUFFER_USAGE_TRANSFORM_FEEDBACK_COUNTER_BUFFER_BIT_EXT)