From 7c9bd08df9bed2f364acf234c1371c6065c75924 Mon Sep 17 00:00:00 2001
From: psucien <bad_cast@protonmail.com>
Date: Sun, 9 Feb 2025 17:57:37 +0100
Subject: [PATCH] fix: lower UBO max size to account buffer cache offset

---
 .../backend/spirv/spirv_emit_context.cpp                  | 2 +-
 src/shader_recompiler/info.h                              | 8 +++++---
 src/video_core/renderer_vulkan/vk_instance.cpp            | 8 ++++++++
 src/video_core/renderer_vulkan/vk_rasterizer.cpp          | 2 +-
 4 files changed, 15 insertions(+), 5 deletions(-)

diff --git a/src/shader_recompiler/backend/spirv/spirv_emit_context.cpp b/src/shader_recompiler/backend/spirv/spirv_emit_context.cpp
index 13d727c72..b08c5108b 100644
--- a/src/shader_recompiler/backend/spirv/spirv_emit_context.cpp
+++ b/src/shader_recompiler/backend/spirv/spirv_emit_context.cpp
@@ -634,7 +634,7 @@ void EmitContext::DefineBuffers() {
     for (const auto& desc : info.buffers) {
         const auto sharp = desc.GetSharp(info);
         const bool is_storage = desc.IsStorage(sharp);
-        const u32 array_size = sharp.NumDwords() != 0 ? sharp.NumDwords() : MaxUboDwords;
+        const u32 array_size = sharp.NumDwords() != 0 ? sharp.NumDwords() : Vulkan::MaxUboSize >> 2;
         const auto* data_types = True(desc.used_types & IR::Type::F32) ? &F32 : &U32;
         const Id data_type = (*data_types)[1];
         const Id record_array_type{is_storage ? TypeRuntimeArray(data_type)
diff --git a/src/shader_recompiler/info.h b/src/shader_recompiler/info.h
index 498752607..9516d9917 100644
--- a/src/shader_recompiler/info.h
+++ b/src/shader_recompiler/info.h
@@ -21,11 +21,13 @@
 #include "video_core/amdgpu/liverpool.h"
 #include "video_core/amdgpu/resource.h"
 
+namespace Vulkan {
+extern size_t MaxUboSize;
+}
+
 namespace Shader {
 
 static constexpr size_t NumUserDataRegs = 16;
-static constexpr size_t MaxUboSize = 65536;
-static constexpr size_t MaxUboDwords = MaxUboSize >> 2;
 
 enum class TextureType : u32 {
     Color1D,
@@ -51,7 +53,7 @@ struct BufferResource {
     bool is_formatted{};
 
     [[nodiscard]] bool IsStorage(const AmdGpu::Buffer& buffer) const noexcept {
-        return buffer.GetSize() > MaxUboSize || is_written || is_gds_buffer;
+        return buffer.GetSize() > Vulkan::MaxUboSize || is_written || is_gds_buffer;
     }
 
     [[nodiscard]] constexpr AmdGpu::Buffer GetSharp(const Info& info) const noexcept;
diff --git a/src/video_core/renderer_vulkan/vk_instance.cpp b/src/video_core/renderer_vulkan/vk_instance.cpp
index e64cae87d..db7ec86a7 100644
--- a/src/video_core/renderer_vulkan/vk_instance.cpp
+++ b/src/video_core/renderer_vulkan/vk_instance.cpp
@@ -19,6 +19,8 @@
 
 namespace Vulkan {
 
+size_t MaxUboSize = 64_KB;
+
 namespace {
 
 std::vector<vk::PhysicalDevice> EnumeratePhysicalDevices(vk::UniqueInstance& instance) {
@@ -180,6 +182,12 @@ Instance::Instance(Frontend::WindowSDL& window, s32 physical_device_index,
                         vk::to_string(format.flags & ~GetFormatFeatureFlags(format.vk_format)));
         }
     }
+
+    // When binding a UBO, we calculate its size considering the offset in the larger buffer cache
+    // underlying resource. In some cases, it may produce sizes exceeding the system maximum
+    // allowed UBO range, so we need to reduce the threshold to prevent issues.
+    MaxUboSize =
+        properties.limits.maxUniformBufferRange - properties.limits.minUniformBufferOffsetAlignment;
 }
 
 Instance::~Instance() {
diff --git a/src/video_core/renderer_vulkan/vk_rasterizer.cpp b/src/video_core/renderer_vulkan/vk_rasterizer.cpp
index 6f979a734..ffd9f4823 100644
--- a/src/video_core/renderer_vulkan/vk_rasterizer.cpp
+++ b/src/video_core/renderer_vulkan/vk_rasterizer.cpp
@@ -554,7 +554,6 @@ void Rasterizer::BindBuffers(const Shader::Info& stage, Shader::Backend::Binding
     }
 
     // Second pass to re-bind buffers that were updated after binding
-    auto& null_buffer = buffer_cache.GetBuffer(VideoCore::NULL_BUFFER_ID);
     for (u32 i = 0; i < buffer_bindings.size(); i++) {
         const auto& [buffer_id, vsharp] = buffer_bindings[i];
         const auto& desc = stage.buffers[i];
@@ -566,6 +565,7 @@ void Rasterizer::BindBuffers(const Shader::Info& stage, Shader::Backend::Binding
             } else if (instance.IsNullDescriptorSupported()) {
                 buffer_infos.emplace_back(VK_NULL_HANDLE, 0, VK_WHOLE_SIZE);
             } else {
+                auto& null_buffer = buffer_cache.GetBuffer(VideoCore::NULL_BUFFER_ID);
                 buffer_infos.emplace_back(null_buffer.Handle(), 0, VK_WHOLE_SIZE);
             }
         } else {