From 37550501ccaba65fd91f22b24c2f30ac7245c771 Mon Sep 17 00:00:00 2001
From: Stenzek <stenzek@gmail.com>
Date: Wed, 30 Nov 2016 22:13:55 +1000
Subject: [PATCH 1/5] Vulkan: Fix incorrect handling of buffer wrap-around in
 StreamBuffer

This was happening when a fence wait happened mid-frame. The data written
between the fence being queued and the allocation occuring was incorrectly
assumed to be consumed by the GPU.
---
 .../VideoBackends/Vulkan/StreamBuffer.cpp     | 36 +++++++++----------
 1 file changed, 18 insertions(+), 18 deletions(-)

diff --git a/Source/Core/VideoBackends/Vulkan/StreamBuffer.cpp b/Source/Core/VideoBackends/Vulkan/StreamBuffer.cpp
index 4d90401bcf..6cf55ab0f2 100644
--- a/Source/Core/VideoBackends/Vulkan/StreamBuffer.cpp
+++ b/Source/Core/VideoBackends/Vulkan/StreamBuffer.cpp
@@ -286,8 +286,11 @@ bool StreamBuffer::WaitForClearSpace(size_t num_bytes)
   for (; iter != m_tracked_fences.end(); iter++)
   {
     // Would this fence bring us in line with the GPU?
+    // This is the "last resort" case, where a command buffer execution has been forced
+    // after no additional data has been written to it, so we can assume that after the
+    // fence has been signaled the entire buffer is now consumed.
     size_t gpu_position = iter->second;
-    if (gpu_position == m_current_offset)
+    if (m_current_offset == gpu_position)
     {
       // Start at the start of the buffer again.
       new_offset = 0;
@@ -295,12 +298,12 @@ bool StreamBuffer::WaitForClearSpace(size_t num_bytes)
       break;
     }
 
-    // We can wrap around to the start, behind the GPU, if there is enough space.
-    // We use > here because otherwise we'd end up lining up with the GPU, and then the
-    // allocator would assume that the GPU has consumed what we just wrote.
-    if (m_current_offset >= m_current_gpu_position)
+    // Assuming that we wait for this fence, are we allocating in front of the GPU?
+    if (m_current_offset > gpu_position)
     {
-      // Wrap around to the start (behind the GPU) if there is sufficient space.
+      // We can wrap around to the start, behind the GPU, if there is enough space.
+      // We use > here because otherwise we'd end up lining up with the GPU, and then the
+      // allocator would assume that the GPU has consumed what we just wrote.
       if (gpu_position > num_bytes)
       {
         new_offset = 0;
@@ -310,19 +313,16 @@ bool StreamBuffer::WaitForClearSpace(size_t num_bytes)
     }
     else
     {
-      // We're currently allocating behind the GPU. Therefore, if this fence is behind us,
-      // and it's the last fence in the list (no data has been written after it), we can
-      // move back to allocating in front of the GPU.
-      if (gpu_position < m_current_offset)
+      // We're currently allocating behind the GPU. This would give us between the current
+      // offset and the GPU position worth of space to work with. Again, > because we can't
+      // align the GPU position with the buffer offset.
+      size_t available_space_inbetween = m_current_offset - gpu_position;
+      if (available_space_inbetween > num_bytes)
       {
-        if (std::none_of(iter, m_tracked_fences.end(),
-                         [gpu_position](const auto& it) { return it.second > gpu_position; }))
-        {
-          // Wait for this fence to complete, then allocate directly after it.
-          new_offset = gpu_position;
-          new_gpu_position = gpu_position;
-          break;
-        }
+        // Leave the offset as-is, but update the GPU position.
+        new_offset = m_current_offset;
+        new_gpu_position = gpu_position;
+        break;
       }
     }
   }

From 4c11735bd5a9d99304d3f641fe615533dc157b8e Mon Sep 17 00:00:00 2001
From: Stenzek <stenzek@gmail.com>
Date: Wed, 30 Nov 2016 22:20:44 +1000
Subject: [PATCH 2/5] Vulkan: Fix case where a draw's vertices could be
 overwritten

This could happen because the vertex memory was already committed, if a
uniform buffer allocation failed and caused a command buffer to be
executed, it would be associated with the previous command buffer rather
than the buffer containing the draw that consumed these vertices.
---
 Source/Core/VideoBackends/Vulkan/VertexManager.cpp | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/Source/Core/VideoBackends/Vulkan/VertexManager.cpp b/Source/Core/VideoBackends/Vulkan/VertexManager.cpp
index 8300fb5fdd..f3116a8cb6 100644
--- a/Source/Core/VideoBackends/Vulkan/VertexManager.cpp
+++ b/Source/Core/VideoBackends/Vulkan/VertexManager.cpp
@@ -130,9 +130,6 @@ void VertexManager::vFlush(bool use_dst_alpha)
       static_cast<VertexFormat*>(VertexLoaderManager::GetCurrentVertexFormat());
   u32 vertex_stride = vertex_format->GetVertexStride();
 
-  // Commit memory to device
-  PrepareDrawBuffers(vertex_stride);
-
   // Figure out the number of indices to draw
   u32 index_count = IndexGenerator::GetIndexLen();
 
@@ -169,6 +166,12 @@ void VertexManager::vFlush(bool use_dst_alpha)
   StateTracker::GetInstance()->UpdateGeometryShaderConstants();
   StateTracker::GetInstance()->UpdatePixelShaderConstants();
 
+  // Commit memory to device.
+  // NOTE: This must be done after constant upload, as a constant buffer overrun can cause
+  // the current command buffer to be executed, and we want the buffer space to be associated
+  // with the command buffer that has the corresponding draw.
+  PrepareDrawBuffers(vertex_stride);
+
   // Flush all EFB pokes and invalidate the peek cache.
   FramebufferManager::GetInstance()->InvalidatePeekCache();
   FramebufferManager::GetInstance()->FlushEFBPokes();

From 3adeacb78d6c313020ea6f2562f76856f9431ec1 Mon Sep 17 00:00:00 2001
From: Stenzek <stenzek@gmail.com>
Date: Wed, 30 Nov 2016 22:31:41 +1000
Subject: [PATCH 3/5] Vulkan: Fix case where uniforms could be overwritten

If a draw caused a command buffer submission, the current uniform storage
should not be used for the new command buffer.
---
 .../VideoBackends/Vulkan/StateTracker.cpp     | 28 ++++++++++---------
 .../Core/VideoBackends/Vulkan/StateTracker.h  |  3 ++
 Source/Core/VideoBackends/Vulkan/Util.cpp     |  1 +
 3 files changed, 19 insertions(+), 13 deletions(-)

diff --git a/Source/Core/VideoBackends/Vulkan/StateTracker.cpp b/Source/Core/VideoBackends/Vulkan/StateTracker.cpp
index c7c4c77c54..40a32b0087 100644
--- a/Source/Core/VideoBackends/Vulkan/StateTracker.cpp
+++ b/Source/Core/VideoBackends/Vulkan/StateTracker.cpp
@@ -467,26 +467,21 @@ void StateTracker::UpdatePixelShaderConstants()
 void StateTracker::UploadAllConstants()
 {
   // We are free to re-use parts of the buffer now since we're uploading all constants.
+  size_t ub_alignment = g_vulkan_context->GetUniformBufferAlignment();
   size_t pixel_constants_offset = 0;
   size_t vertex_constants_offset =
-      Util::AlignValue(pixel_constants_offset + sizeof(PixelShaderConstants),
-                       g_vulkan_context->GetUniformBufferAlignment());
+      Util::AlignValue(pixel_constants_offset + sizeof(PixelShaderConstants), ub_alignment);
   size_t geometry_constants_offset =
-      Util::AlignValue(vertex_constants_offset + sizeof(VertexShaderConstants),
-                       g_vulkan_context->GetUniformBufferAlignment());
-  size_t total_allocation_size = geometry_constants_offset + sizeof(GeometryShaderConstants);
+      Util::AlignValue(vertex_constants_offset + sizeof(VertexShaderConstants), ub_alignment);
+  size_t allocation_size = geometry_constants_offset + sizeof(GeometryShaderConstants);
 
   // Allocate everything at once.
-  if (!m_uniform_stream_buffer->ReserveMemory(
-          total_allocation_size, g_vulkan_context->GetUniformBufferAlignment(), true, true, false))
+  if (!m_uniform_stream_buffer->ReserveMemory(allocation_size, ub_alignment, true, true, false))
   {
-    // If this fails, wait until the GPU has caught up.
     // The only places that call constant updates are safe to have state restored.
-    WARN_LOG(VIDEO, "Executing command list while waiting for space in uniform buffer");
+    WARN_LOG(VIDEO, "Executing command buffer while waiting for space in uniform buffer");
     Util::ExecuteCurrentCommandsAndRestoreState(false);
-    if (!m_uniform_stream_buffer->ReserveMemory(total_allocation_size,
-                                                g_vulkan_context->GetUniformBufferAlignment(), true,
-                                                true, false))
+    if (!m_uniform_stream_buffer->ReserveMemory(allocation_size, ub_alignment, true, true, false))
     {
       PanicAlert("Failed to allocate space for constants in streaming buffer");
       return;
@@ -528,7 +523,7 @@ void StateTracker::UploadAllConstants()
          &GeometryShaderManager::constants, sizeof(GeometryShaderConstants));
 
   // Finally, flush buffer memory after copying
-  m_uniform_stream_buffer->CommitMemory(total_allocation_size);
+  m_uniform_stream_buffer->CommitMemory(allocation_size);
 
   // Clear dirty flags
   VertexShaderManager::dirty = false;
@@ -616,6 +611,13 @@ void StateTracker::InvalidateDescriptorSets()
     m_dirty_flags &= ~DIRTY_FLAG_PS_SSBO;
 }
 
+void StateTracker::InvalidateConstants()
+{
+  VertexShaderManager::dirty = true;
+  GeometryShaderManager::dirty = true;
+  PixelShaderManager::dirty = true;
+}
+
 void StateTracker::SetPendingRebind()
 {
   m_dirty_flags |= DIRTY_FLAG_DYNAMIC_OFFSETS | DIRTY_FLAG_DESCRIPTOR_SET_BINDING |
diff --git a/Source/Core/VideoBackends/Vulkan/StateTracker.h b/Source/Core/VideoBackends/Vulkan/StateTracker.h
index a42a9dc72d..57602d2233 100644
--- a/Source/Core/VideoBackends/Vulkan/StateTracker.h
+++ b/Source/Core/VideoBackends/Vulkan/StateTracker.h
@@ -76,6 +76,9 @@ public:
   // now be in a different pool for the new command buffer.
   void InvalidateDescriptorSets();
 
+  // Same with the uniforms, as the current storage will belong to the previous command buffer.
+  void InvalidateConstants();
+
   // Set dirty flags on everything to force re-bind at next draw time.
   void SetPendingRebind();
 
diff --git a/Source/Core/VideoBackends/Vulkan/Util.cpp b/Source/Core/VideoBackends/Vulkan/Util.cpp
index 2e8025dbc1..e92c070fc8 100644
--- a/Source/Core/VideoBackends/Vulkan/Util.cpp
+++ b/Source/Core/VideoBackends/Vulkan/Util.cpp
@@ -200,6 +200,7 @@ void ExecuteCurrentCommandsAndRestoreState(bool execute_off_thread, bool wait_fo
   StateTracker::GetInstance()->EndRenderPass();
   g_command_buffer_mgr->ExecuteCommandBuffer(execute_off_thread, wait_for_completion);
   StateTracker::GetInstance()->InvalidateDescriptorSets();
+  StateTracker::GetInstance()->InvalidateConstants();
   StateTracker::GetInstance()->SetPendingRebind();
 }
 

From 6a4eba1153b7fc858aca895f17b57dc03f089860 Mon Sep 17 00:00:00 2001
From: Stenzek <stenzek@gmail.com>
Date: Wed, 30 Nov 2016 22:34:36 +1000
Subject: [PATCH 4/5] Vulkan: Replace explicit command buffer submits with
 wrapper function

Should we ever introduce anything else that has to be done when a command
buffer is executed (e.g. invalidating constants from previous commit), we
don't have to update all the callers.
---
 .../Core/VideoBackends/Vulkan/FramebufferManager.cpp  | 10 +++-------
 Source/Core/VideoBackends/Vulkan/Renderer.cpp         |  1 +
 Source/Core/VideoBackends/Vulkan/StateTracker.cpp     | 11 ++---------
 Source/Core/VideoBackends/Vulkan/TextureCache.cpp     | 10 ++++------
 Source/Core/VideoBackends/Vulkan/TextureEncoder.cpp   |  4 +---
 5 files changed, 11 insertions(+), 25 deletions(-)

diff --git a/Source/Core/VideoBackends/Vulkan/FramebufferManager.cpp b/Source/Core/VideoBackends/Vulkan/FramebufferManager.cpp
index f01f8ac25b..774afbf79d 100644
--- a/Source/Core/VideoBackends/Vulkan/FramebufferManager.cpp
+++ b/Source/Core/VideoBackends/Vulkan/FramebufferManager.cpp
@@ -738,9 +738,7 @@ bool FramebufferManager::PopulateColorReadbackTexture()
   }
 
   // Wait until the copy is complete.
-  g_command_buffer_mgr->ExecuteCommandBuffer(false, true);
-  StateTracker::GetInstance()->InvalidateDescriptorSets();
-  StateTracker::GetInstance()->SetPendingRebind();
+  Util::ExecuteCurrentCommandsAndRestoreState(false, true);
 
   // Map to host memory.
   if (!m_color_readback_texture->IsMapped() && !m_color_readback_texture->Map())
@@ -822,9 +820,7 @@ bool FramebufferManager::PopulateDepthReadbackTexture()
   }
 
   // Wait until the copy is complete.
-  g_command_buffer_mgr->ExecuteCommandBuffer(false, true);
-  StateTracker::GetInstance()->InvalidateDescriptorSets();
-  StateTracker::GetInstance()->SetPendingRebind();
+  Util::ExecuteCurrentCommandsAndRestoreState(false, true);
 
   // Map to host memory.
   if (!m_depth_readback_texture->IsMapped() && !m_depth_readback_texture->Map())
@@ -1212,7 +1208,7 @@ void FramebufferManager::DrawPokeVertices(const EFBPokeVertex* vertices, size_t
   {
     // Kick a command buffer first.
     WARN_LOG(VIDEO, "Kicking command buffer due to no EFB poke space.");
-    Util::ExecuteCurrentCommandsAndRestoreState(true);
+    Util::ExecuteCurrentCommandsAndRestoreState(false);
     command_buffer = g_command_buffer_mgr->GetCurrentCommandBuffer();
 
     if (!m_poke_vertex_stream_buffer->ReserveMemory(vertices_size, sizeof(EfbPokeData), true, true,
diff --git a/Source/Core/VideoBackends/Vulkan/Renderer.cpp b/Source/Core/VideoBackends/Vulkan/Renderer.cpp
index f26117a084..2b8e0b63a6 100644
--- a/Source/Core/VideoBackends/Vulkan/Renderer.cpp
+++ b/Source/Core/VideoBackends/Vulkan/Renderer.cpp
@@ -326,6 +326,7 @@ void Renderer::BeginFrame()
   // Ensure that the state tracker rebinds everything, and allocates a new set
   // of descriptors out of the next pool.
   StateTracker::GetInstance()->InvalidateDescriptorSets();
+  StateTracker::GetInstance()->InvalidateConstants();
   StateTracker::GetInstance()->SetPendingRebind();
 }
 
diff --git a/Source/Core/VideoBackends/Vulkan/StateTracker.cpp b/Source/Core/VideoBackends/Vulkan/StateTracker.cpp
index 40a32b0087..67583782c9 100644
--- a/Source/Core/VideoBackends/Vulkan/StateTracker.cpp
+++ b/Source/Core/VideoBackends/Vulkan/StateTracker.cpp
@@ -710,11 +710,7 @@ bool StateTracker::Bind(bool rebind_all /*= false*/)
   {
     // We can fail to allocate descriptors if we exhaust the pool for this command buffer.
     WARN_LOG(VIDEO, "Failed to get a descriptor set, executing buffer");
-
-    // Try again after executing the current buffer.
-    g_command_buffer_mgr->ExecuteCommandBuffer(false, false);
-    InvalidateDescriptorSets();
-    SetPendingRebind();
+    Util::ExecuteCurrentCommandsAndRestoreState(false, false);
     if (!UpdateDescriptorSet())
     {
       // Something strange going on.
@@ -777,10 +773,7 @@ void StateTracker::OnDraw()
                          m_scheduled_command_buffer_kicks.end(), m_draw_counter))
   {
     // Kick a command buffer on the background thread.
-    EndRenderPass();
-    g_command_buffer_mgr->ExecuteCommandBuffer(true, false);
-    InvalidateDescriptorSets();
-    SetPendingRebind();
+    Util::ExecuteCurrentCommandsAndRestoreState(true);
   }
 }
 
diff --git a/Source/Core/VideoBackends/Vulkan/TextureCache.cpp b/Source/Core/VideoBackends/Vulkan/TextureCache.cpp
index d52ba671db..b607a91fd0 100644
--- a/Source/Core/VideoBackends/Vulkan/TextureCache.cpp
+++ b/Source/Core/VideoBackends/Vulkan/TextureCache.cpp
@@ -145,10 +145,10 @@ void TextureCache::CopyEFB(u8* dst, u32 format, u32 native_width, u32 bytes_per_
   else
     src_texture = FramebufferManager::GetInstance()->ResolveEFBColorTexture(region);
 
-  // End render pass before barrier (since we have no self-dependencies)
+  // End render pass before barrier (since we have no self-dependencies).
+  // The barrier has to happen after the render pass, not inside it, as we are going to be
+  // reading from the texture immediately afterwards.
   StateTracker::GetInstance()->EndRenderPass();
-  StateTracker::GetInstance()->SetPendingRebind();
-  StateTracker::GetInstance()->InvalidateDescriptorSets();
   StateTracker::GetInstance()->OnReadback();
 
   // Transition to shader resource before reading.
@@ -666,9 +666,7 @@ bool TextureCache::TCacheEntry::Save(const std::string& filename, unsigned int l
                                 VK_IMAGE_LAYOUT_SHADER_READ_ONLY_OPTIMAL);
 
   // Block until the GPU has finished copying to the staging texture.
-  g_command_buffer_mgr->ExecuteCommandBuffer(false, true);
-  StateTracker::GetInstance()->InvalidateDescriptorSets();
-  StateTracker::GetInstance()->SetPendingRebind();
+  Util::ExecuteCurrentCommandsAndRestoreState(false, true);
 
   // Map the staging texture so we can copy the contents out.
   if (staging_texture->Map())
diff --git a/Source/Core/VideoBackends/Vulkan/TextureEncoder.cpp b/Source/Core/VideoBackends/Vulkan/TextureEncoder.cpp
index 404b30b09c..77a443a9e0 100644
--- a/Source/Core/VideoBackends/Vulkan/TextureEncoder.cpp
+++ b/Source/Core/VideoBackends/Vulkan/TextureEncoder.cpp
@@ -121,9 +121,7 @@ void TextureEncoder::EncodeTextureToRam(VkImageView src_texture, u8* dest_ptr, u
                                     render_width, render_height, 0, 0);
 
   // Block until the GPU has finished copying to the staging texture.
-  g_command_buffer_mgr->ExecuteCommandBuffer(false, true);
-  StateTracker::GetInstance()->InvalidateDescriptorSets();
-  StateTracker::GetInstance()->SetPendingRebind();
+  Util::ExecuteCurrentCommandsAndRestoreState(false, true);
 
   // Copy from staging texture to the final destination, adjusting pitch if necessary.
   m_download_texture->ReadTexels(0, 0, render_width, render_height, dest_ptr, memory_stride);

From ca691a9d95c437334cfeb8321a544ed36d17849b Mon Sep 17 00:00:00 2001
From: Stenzek <stenzek@gmail.com>
Date: Wed, 30 Nov 2016 23:32:23 +1000
Subject: [PATCH 5/5] Vulkan: Allow re-use of uniform buffers when doing
 per-stage uploads

This is safe now because we invalidate the pointers after submitting a
command buffer.
---
 .../VideoBackends/Vulkan/StateTracker.cpp     | 70 ++++++++-----------
 .../Core/VideoBackends/Vulkan/StateTracker.h  |  5 ++
 2 files changed, 33 insertions(+), 42 deletions(-)

diff --git a/Source/Core/VideoBackends/Vulkan/StateTracker.cpp b/Source/Core/VideoBackends/Vulkan/StateTracker.cpp
index 67583782c9..700f1d1057 100644
--- a/Source/Core/VideoBackends/Vulkan/StateTracker.cpp
+++ b/Source/Core/VideoBackends/Vulkan/StateTracker.cpp
@@ -357,20 +357,9 @@ bool StateTracker::CheckForShaderChanges(u32 gx_primitive_type, DSTALPHA_MODE ds
 
 void StateTracker::UpdateVertexShaderConstants()
 {
-  if (!VertexShaderManager::dirty)
+  if (!VertexShaderManager::dirty || !ReserveConstantStorage())
     return;
 
-  // Since the other stages uniform buffers' may be still be using the earlier data,
-  // we can't reuse the earlier part of the buffer without re-uploading everything.
-  if (!m_uniform_stream_buffer->ReserveMemory(m_uniform_buffer_reserve_size,
-                                              g_vulkan_context->GetUniformBufferAlignment(), false,
-                                              false, false))
-  {
-    // Re-upload all constants to a new portion of the buffer.
-    UploadAllConstants();
-    return;
-  }
-
   // Buffer allocation changed?
   if (m_uniform_stream_buffer->GetBuffer() !=
       m_bindings.uniform_buffer_bindings[UBO_DESCRIPTOR_SET_BINDING_VS].buffer)
@@ -394,17 +383,9 @@ void StateTracker::UpdateVertexShaderConstants()
 void StateTracker::UpdateGeometryShaderConstants()
 {
   // Skip updating geometry shader constants if it's not in use.
-  if (m_pipeline_state.gs == VK_NULL_HANDLE || !GeometryShaderManager::dirty)
-    return;
-
-  // Since the other stages uniform buffers' may be still be using the earlier data,
-  // we can't reuse the earlier part of the buffer without re-uploading everything.
-  if (!m_uniform_stream_buffer->ReserveMemory(m_uniform_buffer_reserve_size,
-                                              g_vulkan_context->GetUniformBufferAlignment(), false,
-                                              false, false))
+  if (m_pipeline_state.gs == VK_NULL_HANDLE || !GeometryShaderManager::dirty ||
+      !ReserveConstantStorage())
   {
-    // Re-upload all constants to a new portion of the buffer.
-    UploadAllConstants();
     return;
   }
 
@@ -430,20 +411,9 @@ void StateTracker::UpdateGeometryShaderConstants()
 
 void StateTracker::UpdatePixelShaderConstants()
 {
-  if (!PixelShaderManager::dirty)
+  if (!PixelShaderManager::dirty || !ReserveConstantStorage())
     return;
 
-  // Since the other stages uniform buffers' may be still be using the earlier data,
-  // we can't reuse the earlier part of the buffer without re-uploading everything.
-  if (!m_uniform_stream_buffer->ReserveMemory(m_uniform_buffer_reserve_size,
-                                              g_vulkan_context->GetUniformBufferAlignment(), false,
-                                              false, false))
-  {
-    // Re-upload all constants to a new portion of the buffer.
-    UploadAllConstants();
-    return;
-  }
-
   // Buffer allocation changed?
   if (m_uniform_stream_buffer->GetBuffer() !=
       m_bindings.uniform_buffer_bindings[UBO_DESCRIPTOR_SET_BINDING_PS].buffer)
@@ -464,6 +434,27 @@ void StateTracker::UpdatePixelShaderConstants()
   PixelShaderManager::dirty = false;
 }
 
+bool StateTracker::ReserveConstantStorage()
+{
+  // Since we invalidate all constants on command buffer execution, it doesn't matter if this
+  // causes the stream buffer to be resized.
+  if (m_uniform_stream_buffer->ReserveMemory(m_uniform_buffer_reserve_size,
+                                             g_vulkan_context->GetUniformBufferAlignment(), true,
+                                             true, false))
+  {
+    return true;
+  }
+
+  // The only places that call constant updates are safe to have state restored.
+  WARN_LOG(VIDEO, "Executing command buffer while waiting for space in uniform buffer");
+  Util::ExecuteCurrentCommandsAndRestoreState(false);
+
+  // Since we are on a new command buffer, all constants have been invalidated, and we need
+  // to reupload them. We may as well do this now, since we're issuing a draw anyway.
+  UploadAllConstants();
+  return false;
+}
+
 void StateTracker::UploadAllConstants()
 {
   // We are free to re-use parts of the buffer now since we're uploading all constants.
@@ -476,16 +467,11 @@ void StateTracker::UploadAllConstants()
   size_t allocation_size = geometry_constants_offset + sizeof(GeometryShaderConstants);
 
   // Allocate everything at once.
+  // We should only be here if the buffer was full and a command buffer was submitted anyway.
   if (!m_uniform_stream_buffer->ReserveMemory(allocation_size, ub_alignment, true, true, false))
   {
-    // The only places that call constant updates are safe to have state restored.
-    WARN_LOG(VIDEO, "Executing command buffer while waiting for space in uniform buffer");
-    Util::ExecuteCurrentCommandsAndRestoreState(false);
-    if (!m_uniform_stream_buffer->ReserveMemory(allocation_size, ub_alignment, true, true, false))
-    {
-      PanicAlert("Failed to allocate space for constants in streaming buffer");
-      return;
-    }
+    PanicAlert("Failed to allocate space for constants in streaming buffer");
+    return;
   }
 
   // Update bindings
diff --git a/Source/Core/VideoBackends/Vulkan/StateTracker.h b/Source/Core/VideoBackends/Vulkan/StateTracker.h
index 57602d2233..126041e9bc 100644
--- a/Source/Core/VideoBackends/Vulkan/StateTracker.h
+++ b/Source/Core/VideoBackends/Vulkan/StateTracker.h
@@ -174,6 +174,11 @@ private:
 
   bool UpdatePipeline();
   bool UpdateDescriptorSet();
+
+  // Allocates storage in the uniform buffer of the specified size. If this storage cannot be
+  // allocated immediately, the current command buffer will be submitted and all stage's
+  // constants will be re-uploaded. false will be returned in this case, otherwise true.
+  bool ReserveConstantStorage();
   void UploadAllConstants();
 
   // Which bindings/state has to be updated before the next draw.