20 files changed, 497 insertions, 154 deletions

diff --git a/src/common/CMakeLists.txt b/src/common/CMakeLists.txt
index 25b22a281..eb05e46a8 100644
--- a/src/common/CMakeLists.txt
+++ b/src/common/CMakeLists.txt
@@ -78,6 +78,7 @@ add_library(common STATIC
     logging/types.h
     lz4_compression.cpp
     lz4_compression.h
+    make_unique_for_overwrite.h
     math_util.h
     memory_detect.cpp
     memory_detect.h
@@ -101,6 +102,7 @@ add_library(common STATIC
     ${CMAKE_CURRENT_BINARY_DIR}/scm_rev.cpp
     scm_rev.h
     scope_exit.h
+    scratch_buffer.h
     settings.cpp
     settings.h
     settings_input.cpp
diff --git a/src/common/make_unique_for_overwrite.h b/src/common/make_unique_for_overwrite.h
new file mode 100644
index 000000000..c7413cf51
--- /dev/null
+++ b/src/common/make_unique_for_overwrite.h
@@ -0,0 +1,25 @@
+// SPDX-FileCopyrightText: Copyright 2022 yuzu Emulator Project
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+#pragma once
+
+#include <memory>
+#include <type_traits>
+
+namespace Common {
+
+template <class T>
+requires(!std::is_array_v<T>) std::unique_ptr<T> make_unique_for_overwrite() {
+    return std::unique_ptr<T>(new T);
+}
+
+template <class T>
+requires std::is_unbounded_array_v<T> std::unique_ptr<T> make_unique_for_overwrite(std::size_t n) {
+    return std::unique_ptr<T>(new std::remove_extent_t<T>[n]);
+}
+
+template <class T, class... Args>
+requires std::is_bounded_array_v<T>
+void make_unique_for_overwrite(Args&&...) = delete;
+
+} // namespace Common
diff --git a/src/common/scratch_buffer.h b/src/common/scratch_buffer.h
new file mode 100644
index 000000000..1245a5086
--- /dev/null
+++ b/src/common/scratch_buffer.h
@@ -0,0 +1,95 @@
+// SPDX-FileCopyrightText: Copyright 2022 yuzu Emulator Project
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+#pragma once
+
+#include "common/make_unique_for_overwrite.h"
+
+namespace Common {
+
+/**
+ * ScratchBuffer class
+ * This class creates a default initialized heap allocated buffer for cases such as intermediate
+ * buffers being copied into entirely, where value initializing members during allocation or resize
+ * is redundant.
+ */
+template <typename T>
+class ScratchBuffer {
+public:
+    ScratchBuffer() = default;
+
+    explicit ScratchBuffer(size_t initial_capacity)
+        : last_requested_size{initial_capacity}, buffer_capacity{initial_capacity},
+          buffer{Common::make_unique_for_overwrite<T[]>(initial_capacity)} {}
+
+    ~ScratchBuffer() = default;
+
+    /// This will only grow the buffer's capacity if size is greater than the current capacity.
+    /// The previously held data will remain intact.
+    void resize(size_t size) {
+        if (size > buffer_capacity) {
+            auto new_buffer = Common::make_unique_for_overwrite<T[]>(size);
+            std::move(buffer.get(), buffer.get() + buffer_capacity, new_buffer.get());
+            buffer = std::move(new_buffer);
+            buffer_capacity = size;
+        }
+        last_requested_size = size;
+    }
+
+    /// This will only grow the buffer's capacity if size is greater than the current capacity.
+    /// The previously held data will be destroyed if a reallocation occurs.
+    void resize_destructive(size_t size) {
+        if (size > buffer_capacity) {
+            buffer_capacity = size;
+            buffer = Common::make_unique_for_overwrite<T[]>(buffer_capacity);
+        }
+        last_requested_size = size;
+    }
+
+    [[nodiscard]] T* data() noexcept {
+        return buffer.get();
+    }
+
+    [[nodiscard]] const T* data() const noexcept {
+        return buffer.get();
+    }
+
+    [[nodiscard]] T* begin() noexcept {
+        return data();
+    }
+
+    [[nodiscard]] const T* begin() const noexcept {
+        return data();
+    }
+
+    [[nodiscard]] T* end() noexcept {
+        return data() + last_requested_size;
+    }
+
+    [[nodiscard]] const T* end() const noexcept {
+        return data() + last_requested_size;
+    }
+
+    [[nodiscard]] T& operator[](size_t i) {
+        return buffer[i];
+    }
+
+    [[nodiscard]] const T& operator[](size_t i) const {
+        return buffer[i];
+    }
+
+    [[nodiscard]] size_t size() const noexcept {
+        return last_requested_size;
+    }
+
+    [[nodiscard]] size_t capacity() const noexcept {
+        return buffer_capacity;
+    }
+
+private:
+    size_t last_requested_size{};
+    size_t buffer_capacity{};
+    std::unique_ptr<T[]> buffer{};
+};
+
+} // namespace Common
diff --git a/src/core/hle/kernel/k_shared_memory.cpp b/src/core/hle/kernel/k_shared_memory.cpp
index 10cd4c43d..0aa68103c 100644
--- a/src/core/hle/kernel/k_shared_memory.cpp
+++ b/src/core/hle/kernel/k_shared_memory.cpp
@@ -6,6 +6,7 @@
 #include "core/hle/kernel/k_page_table.h"
 #include "core/hle/kernel/k_scoped_resource_reservation.h"
 #include "core/hle/kernel/k_shared_memory.h"
+#include "core/hle/kernel/k_system_resource.h"
 #include "core/hle/kernel/kernel.h"
 #include "core/hle/kernel/svc_results.h"
 
@@ -18,19 +19,19 @@ KSharedMemory::~KSharedMemory() {
 }
 
 Result KSharedMemory::Initialize(Core::DeviceMemory& device_memory_, KProcess* owner_process_,
-                                 KPageGroup&& page_list_, Svc::MemoryPermission owner_permission_,
-                                 Svc::MemoryPermission user_permission_, PAddr physical_address_,
-                                 std::size_t size_, std::string name_) {
+                                 Svc::MemoryPermission owner_permission_,
+                                 Svc::MemoryPermission user_permission_, std::size_t size_,
+                                 std::string name_) {
     // Set members.
     owner_process = owner_process_;
     device_memory = &device_memory_;
-    page_list = std::move(page_list_);
     owner_permission = owner_permission_;
     user_permission = user_permission_;
-    physical_address = physical_address_;
-    size = size_;
+    size = Common::AlignUp(size_, PageSize);
     name = std::move(name_);
 
+    const size_t num_pages = Common::DivideUp(size, PageSize);
+
     // Get the resource limit.
     KResourceLimit* reslimit = kernel.GetSystemResourceLimit();
 
@@ -39,6 +40,17 @@ Result KSharedMemory::Initialize(Core::DeviceMemory& device_memory_, KProcess* o
                                                   size_);
     R_UNLESS(memory_reservation.Succeeded(), ResultLimitReached);
 
+    // Allocate the memory.
+
+    //! HACK: Open continuous mapping from sysmodule pool.
+    auto option = KMemoryManager::EncodeOption(KMemoryManager::Pool::Secure,
+                                               KMemoryManager::Direction::FromBack);
+    physical_address = kernel.MemoryManager().AllocateAndOpenContinuous(num_pages, 1, option);
+    R_UNLESS(physical_address != 0, ResultOutOfMemory);
+
+    //! Insert the result into our page group.
+    page_group.emplace(physical_address, num_pages);
+
     // Commit our reservation.
     memory_reservation.Commit();
 
@@ -50,12 +62,23 @@ Result KSharedMemory::Initialize(Core::DeviceMemory& device_memory_, KProcess* o
     is_initialized = true;
 
     // Clear all pages in the memory.
-    std::memset(device_memory_.GetPointer<void>(physical_address_), 0, size_);
+    for (const auto& block : page_group->Nodes()) {
+        std::memset(device_memory_.GetPointer<void>(block.GetAddress()), 0, block.GetSize());
+    }
 
     return ResultSuccess;
 }
 
 void KSharedMemory::Finalize() {
+    // Close and finalize the page group.
+    // page_group->Close();
+    // page_group->Finalize();
+
+    //! HACK: Manually close.
+    for (const auto& block : page_group->Nodes()) {
+        kernel.MemoryManager().Close(block.GetAddress(), block.GetNumPages());
+    }
+
     // Release the memory reservation.
     resource_limit->Release(LimitableResource::PhysicalMemoryMax, size);
     resource_limit->Close();
@@ -65,32 +88,28 @@ void KSharedMemory::Finalize() {
 }
 
 Result KSharedMemory::Map(KProcess& target_process, VAddr address, std::size_t map_size,
-                          Svc::MemoryPermission permissions) {
-    const u64 page_count{(map_size + PageSize - 1) / PageSize};
-
-    if (page_list.GetNumPages() != page_count) {
-        UNIMPLEMENTED_MSG("Page count does not match");
-    }
+                          Svc::MemoryPermission map_perm) {
+    // Validate the size.
+    R_UNLESS(size == map_size, ResultInvalidSize);
 
-    const Svc::MemoryPermission expected =
+    // Validate the permission.
+    const Svc::MemoryPermission test_perm =
         &target_process == owner_process ? owner_permission : user_permission;
-
-    if (permissions != expected) {
-        UNIMPLEMENTED_MSG("Permission does not match");
+    if (test_perm == Svc::MemoryPermission::DontCare) {
+        ASSERT(map_perm == Svc::MemoryPermission::Read || map_perm == Svc::MemoryPermission::Write);
+    } else {
+        R_UNLESS(map_perm == test_perm, ResultInvalidNewMemoryPermission);
     }
 
-    return target_process.PageTable().MapPages(address, page_list, KMemoryState::Shared,
-                                               ConvertToKMemoryPermission(permissions));
+    return target_process.PageTable().MapPages(address, *page_group, KMemoryState::Shared,
+                                               ConvertToKMemoryPermission(map_perm));
 }
 
 Result KSharedMemory::Unmap(KProcess& target_process, VAddr address, std::size_t unmap_size) {
-    const u64 page_count{(unmap_size + PageSize - 1) / PageSize};
-
-    if (page_list.GetNumPages() != page_count) {
-        UNIMPLEMENTED_MSG("Page count does not match");
-    }
+    // Validate the size.
+    R_UNLESS(size == unmap_size, ResultInvalidSize);
 
-    return target_process.PageTable().UnmapPages(address, page_list, KMemoryState::Shared);
+    return target_process.PageTable().UnmapPages(address, *page_group, KMemoryState::Shared);
 }
 
 } // namespace Kernel
diff --git a/src/core/hle/kernel/k_shared_memory.h b/src/core/hle/kernel/k_shared_memory.h
index a96c55a3e..8b29f0b4a 100644
--- a/src/core/hle/kernel/k_shared_memory.h
+++ b/src/core/hle/kernel/k_shared_memory.h
@@ -3,6 +3,7 @@
 
 #pragma once
 
+#include <optional>
 #include <string>
 
 #include "common/common_types.h"
@@ -26,9 +27,8 @@ public:
     ~KSharedMemory() override;
 
     Result Initialize(Core::DeviceMemory& device_memory_, KProcess* owner_process_,
-                      KPageGroup&& page_list_, Svc::MemoryPermission owner_permission_,
-                      Svc::MemoryPermission user_permission_, PAddr physical_address_,
-                      std::size_t size_, std::string name_);
+                      Svc::MemoryPermission owner_permission_,
+                      Svc::MemoryPermission user_permission_, std::size_t size_, std::string name_);
 
     /**
      * Maps a shared memory block to an address in the target process' address space
@@ -76,7 +76,7 @@ public:
 private:
     Core::DeviceMemory* device_memory{};
     KProcess* owner_process{};
-    KPageGroup page_list;
+    std::optional<KPageGroup> page_group{};
     Svc::MemoryPermission owner_permission{};
     Svc::MemoryPermission user_permission{};
     PAddr physical_address{};
diff --git a/src/core/hle/kernel/kernel.cpp b/src/core/hle/kernel/kernel.cpp
index b75bac5df..1fb25f221 100644
--- a/src/core/hle/kernel/kernel.cpp
+++ b/src/core/hle/kernel/kernel.cpp
@@ -94,6 +94,7 @@ struct KernelCore::Impl {
                                        pt_heap_region.GetSize());
         }
 
+        InitializeHackSharedMemory();
         RegisterHostThread(nullptr);
 
         default_service_thread = &CreateServiceThread(kernel, "DefaultServiceThread");
@@ -726,14 +727,14 @@ struct KernelCore::Impl {
     }
 
     void InitializeMemoryLayout() {
-        const auto system_pool = memory_layout->GetKernelSystemPoolRegionPhysicalExtents();
-
         // Initialize the memory manager.
         memory_manager = std::make_unique<KMemoryManager>(system);
         const auto& management_region = memory_layout->GetPoolManagementRegion();
         ASSERT(management_region.GetEndAddress() != 0);
         memory_manager->Initialize(management_region.GetAddress(), management_region.GetSize());
+    }
 
+    void InitializeHackSharedMemory() {
         // Setup memory regions for emulated processes
         // TODO(bunnei): These should not be hardcoded regions initialized within the kernel
         constexpr std::size_t hid_size{0x40000};
@@ -742,39 +743,23 @@ struct KernelCore::Impl {
         constexpr std::size_t time_size{0x1000};
         constexpr std::size_t hidbus_size{0x1000};
 
-        const PAddr hid_phys_addr{system_pool.GetAddress()};
-        const PAddr font_phys_addr{system_pool.GetAddress() + hid_size};
-        const PAddr irs_phys_addr{system_pool.GetAddress() + hid_size + font_size};
-        const PAddr time_phys_addr{system_pool.GetAddress() + hid_size + font_size + irs_size};
-        const PAddr hidbus_phys_addr{system_pool.GetAddress() + hid_size + font_size + irs_size +
-                                     time_size};
-
         hid_shared_mem = KSharedMemory::Create(system.Kernel());
         font_shared_mem = KSharedMemory::Create(system.Kernel());
         irs_shared_mem = KSharedMemory::Create(system.Kernel());
         time_shared_mem = KSharedMemory::Create(system.Kernel());
         hidbus_shared_mem = KSharedMemory::Create(system.Kernel());
 
-        hid_shared_mem->Initialize(system.DeviceMemory(), nullptr,
-                                   {hid_phys_addr, hid_size / PageSize},
-                                   Svc::MemoryPermission::None, Svc::MemoryPermission::Read,
-                                   hid_phys_addr, hid_size, "HID:SharedMemory");
-        font_shared_mem->Initialize(system.DeviceMemory(), nullptr,
-                                    {font_phys_addr, font_size / PageSize},
-                                    Svc::MemoryPermission::None, Svc::MemoryPermission::Read,
-                                    font_phys_addr, font_size, "Font:SharedMemory");
-        irs_shared_mem->Initialize(system.DeviceMemory(), nullptr,
-                                   {irs_phys_addr, irs_size / PageSize},
-                                   Svc::MemoryPermission::None, Svc::MemoryPermission::Read,
-                                   irs_phys_addr, irs_size, "IRS:SharedMemory");
-        time_shared_mem->Initialize(system.DeviceMemory(), nullptr,
-                                    {time_phys_addr, time_size / PageSize},
-                                    Svc::MemoryPermission::None, Svc::MemoryPermission::Read,
-                                    time_phys_addr, time_size, "Time:SharedMemory");
-        hidbus_shared_mem->Initialize(system.DeviceMemory(), nullptr,
-                                      {hidbus_phys_addr, hidbus_size / PageSize},
-                                      Svc::MemoryPermission::None, Svc::MemoryPermission::Read,
-                                      hidbus_phys_addr, hidbus_size, "HidBus:SharedMemory");
+        hid_shared_mem->Initialize(system.DeviceMemory(), nullptr, Svc::MemoryPermission::None,
+                                   Svc::MemoryPermission::Read, hid_size, "HID:SharedMemory");
+        font_shared_mem->Initialize(system.DeviceMemory(), nullptr, Svc::MemoryPermission::None,
+                                    Svc::MemoryPermission::Read, font_size, "Font:SharedMemory");
+        irs_shared_mem->Initialize(system.DeviceMemory(), nullptr, Svc::MemoryPermission::None,
+                                   Svc::MemoryPermission::Read, irs_size, "IRS:SharedMemory");
+        time_shared_mem->Initialize(system.DeviceMemory(), nullptr, Svc::MemoryPermission::None,
+                                    Svc::MemoryPermission::Read, time_size, "Time:SharedMemory");
+        hidbus_shared_mem->Initialize(system.DeviceMemory(), nullptr, Svc::MemoryPermission::None,
+                                      Svc::MemoryPermission::Read, hidbus_size,
+                                      "HidBus:SharedMemory");
     }
 
     KClientPort* CreateNamedServicePort(std::string name) {
diff --git a/src/core/hle/service/time/clock_types.h b/src/core/hle/service/time/clock_types.h
index ef070f32f..ed1eb5b2d 100644
--- a/src/core/hle/service/time/clock_types.h
+++ b/src/core/hle/service/time/clock_types.h
@@ -49,6 +49,7 @@ struct SteadyClockContext {
 static_assert(sizeof(SteadyClockContext) == 0x18, "SteadyClockContext is incorrect size");
 static_assert(std::is_trivially_copyable_v<SteadyClockContext>,
               "SteadyClockContext must be trivially copyable");
+using StandardSteadyClockTimePointType = SteadyClockContext;
 
 struct SystemClockContext {
     s64 offset;
diff --git a/src/core/hle/service/time/time_sharedmemory.cpp b/src/core/hle/service/time/time_sharedmemory.cpp
index a3aa0e77f..ff53a7d6f 100644
--- a/src/core/hle/service/time/time_sharedmemory.cpp
+++ b/src/core/hle/service/time/time_sharedmemory.cpp
@@ -26,23 +26,24 @@ void SharedMemory::SetupStandardSteadyClock(const Common::UUID& clock_source_id,
     const Clock::SteadyClockContext context{
         static_cast<u64>(current_time_point.nanoseconds - ticks_time_span.nanoseconds),
         clock_source_id};
-    shared_memory_format.standard_steady_clock_timepoint.StoreData(
-        system.Kernel().GetTimeSharedMem().GetPointer(), context);
+    StoreToLockFreeAtomicType(&GetFormat()->standard_steady_clock_timepoint, context);
 }
 
 void SharedMemory::UpdateLocalSystemClockContext(const Clock::SystemClockContext& context) {
-    shared_memory_format.standard_local_system_clock_context.StoreData(
-        system.Kernel().GetTimeSharedMem().GetPointer(), context);
+    StoreToLockFreeAtomicType(&GetFormat()->standard_local_system_clock_context, context);
 }
 
 void SharedMemory::UpdateNetworkSystemClockContext(const Clock::SystemClockContext& context) {
-    shared_memory_format.standard_network_system_clock_context.StoreData(
-        system.Kernel().GetTimeSharedMem().GetPointer(), context);
+    StoreToLockFreeAtomicType(&GetFormat()->standard_network_system_clock_context, context);
 }
 
 void SharedMemory::SetAutomaticCorrectionEnabled(bool is_enabled) {
-    shared_memory_format.standard_user_system_clock_automatic_correction.StoreData(
-        system.Kernel().GetTimeSharedMem().GetPointer(), is_enabled);
+    StoreToLockFreeAtomicType(
+        &GetFormat()->is_standard_user_system_clock_automatic_correction_enabled, is_enabled);
+}
+
+SharedMemory::Format* SharedMemory::GetFormat() {
+    return reinterpret_cast<SharedMemory::Format*>(system.Kernel().GetTimeSharedMem().GetPointer());
 }
 
 } // namespace Service::Time
diff --git a/src/core/hle/service/time/time_sharedmemory.h b/src/core/hle/service/time/time_sharedmemory.h
index 561685acd..044a4d24e 100644
--- a/src/core/hle/service/time/time_sharedmemory.h
+++ b/src/core/hle/service/time/time_sharedmemory.h
@@ -10,45 +10,68 @@
 
 namespace Service::Time {
 
+// Note: this type is not safe for concurrent writes.
+template <typename T>
+struct LockFreeAtomicType {
+    u32 counter_;
+    std::array<T, 2> value_;
+};
+
+template <typename T>
+static inline void StoreToLockFreeAtomicType(LockFreeAtomicType<T>* p, const T& value) {
+    // Get the current counter.
+    auto counter = p->counter_;
+
+    // Increment the counter.
+    ++counter;
+
+    // Store the updated value.
+    p->value_[counter % 2] = value;
+
+    // Fence memory.
+    std::atomic_thread_fence(std::memory_order_release);
+
+    // Set the updated counter.
+    p->counter_ = counter;
+}
+
+template <typename T>
+static inline T LoadFromLockFreeAtomicType(const LockFreeAtomicType<T>* p) {
+    while (true) {
+        // Get the counter.
+        auto counter = p->counter_;
+
+        // Get the value.
+        auto value = p->value_[counter % 2];
+
+        // Fence memory.
+        std::atomic_thread_fence(std::memory_order_acquire);
+
+        // Check that the counter matches.
+        if (counter == p->counter_) {
+            return value;
+        }
+    }
+}
+
 class SharedMemory final {
 public:
     explicit SharedMemory(Core::System& system_);
     ~SharedMemory();
 
-    // TODO(ogniK): We have to properly simulate memory barriers, how are we going to do this?
-    template <typename T, std::size_t Offset>
-    struct MemoryBarrier {
-        static_assert(std::is_trivially_copyable_v<T>, "T must be trivially copyable");
-        u32_le read_attempt{};
-        std::array<T, 2> data{};
-
-        // These are not actually memory barriers at the moment as we don't have multicore and all
-        // HLE is mutexed. This will need to properly be implemented when we start updating the time
-        // points on threads. As of right now, we'll be updated both values synchronously and just
-        // incrementing the read_attempt to indicate that we waited.
-        void StoreData(u8* shared_memory, T data_to_store) {
-            std::memcpy(this, shared_memory + Offset, sizeof(*this));
-            read_attempt++;
-            data[read_attempt & 1] = data_to_store;
-            std::memcpy(shared_memory + Offset, this, sizeof(*this));
-        }
-
-        // For reading we're just going to read the last stored value. If there was no value stored
-        // it will just end up reading an empty value as intended.
-        T ReadData(u8* shared_memory) {
-            std::memcpy(this, shared_memory + Offset, sizeof(*this));
-            return data[(read_attempt - 1) & 1];
-        }
-    };
-
     // Shared memory format
     struct Format {
-        MemoryBarrier<Clock::SteadyClockContext, 0x0> standard_steady_clock_timepoint;
-        MemoryBarrier<Clock::SystemClockContext, 0x38> standard_local_system_clock_context;
-        MemoryBarrier<Clock::SystemClockContext, 0x80> standard_network_system_clock_context;
-        MemoryBarrier<bool, 0xc8> standard_user_system_clock_automatic_correction;
-        u32_le format_version;
+        LockFreeAtomicType<Clock::StandardSteadyClockTimePointType> standard_steady_clock_timepoint;
+        LockFreeAtomicType<Clock::SystemClockContext> standard_local_system_clock_context;
+        LockFreeAtomicType<Clock::SystemClockContext> standard_network_system_clock_context;
+        LockFreeAtomicType<bool> is_standard_user_system_clock_automatic_correction_enabled;
+        u32 format_version;
     };
+    static_assert(offsetof(Format, standard_steady_clock_timepoint) == 0x0);
+    static_assert(offsetof(Format, standard_local_system_clock_context) == 0x38);
+    static_assert(offsetof(Format, standard_network_system_clock_context) == 0x80);
+    static_assert(offsetof(Format, is_standard_user_system_clock_automatic_correction_enabled) ==
+                  0xc8);
     static_assert(sizeof(Format) == 0xd8, "Format is an invalid size");
 
     void SetupStandardSteadyClock(const Common::UUID& clock_source_id,
@@ -56,10 +79,10 @@ public:
     void UpdateLocalSystemClockContext(const Clock::SystemClockContext& context);
     void UpdateNetworkSystemClockContext(const Clock::SystemClockContext& context);
     void SetAutomaticCorrectionEnabled(bool is_enabled);
+    Format* GetFormat();
 
 private:
     Core::System& system;
-    Format shared_memory_format{};
 };
 
 } // namespace Service::Time
diff --git a/src/tests/CMakeLists.txt b/src/tests/CMakeLists.txt
index 348d1edf4..6a4022e45 100644
--- a/src/tests/CMakeLists.txt
+++ b/src/tests/CMakeLists.txt
@@ -8,6 +8,7 @@ add_executable(tests
     common/host_memory.cpp
     common/param_package.cpp
     common/ring_buffer.cpp
+    common/scratch_buffer.cpp
     common/unique_function.cpp
     core/core_timing.cpp
     core/internal_network/network.cpp
diff --git a/src/tests/common/scratch_buffer.cpp b/src/tests/common/scratch_buffer.cpp
new file mode 100644
index 000000000..b602c8d0a
--- /dev/null
+++ b/src/tests/common/scratch_buffer.cpp
@@ -0,0 +1,199 @@
+// SPDX-FileCopyrightText: Copyright 2022 yuzu Emulator Project
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+#include <algorithm>
+#include <array>
+#include <span>
+#include <catch2/catch.hpp>
+#include "common/common_types.h"
+#include "common/scratch_buffer.h"
+
+namespace Common {
+
+TEST_CASE("ScratchBuffer: Basic Test", "[common]") {
+    ScratchBuffer<u8> buf;
+
+    REQUIRE(buf.size() == 0U);
+    REQUIRE(buf.capacity() == 0U);
+
+    std::array<u8, 10> payload;
+    payload.fill(66);
+
+    buf.resize(payload.size());
+    REQUIRE(buf.size() == payload.size());
+    REQUIRE(buf.capacity() == payload.size());
+
+    std::memcpy(buf.data(), payload.data(), payload.size());
+    for (size_t i = 0; i < payload.size(); ++i) {
+        REQUIRE(buf[i] == payload[i]);
+    }
+}
+
+TEST_CASE("ScratchBuffer: resize_destructive Grow", "[common]") {
+    std::array<u8, 10> payload;
+    payload.fill(66);
+
+    ScratchBuffer<u8> buf(payload.size());
+    REQUIRE(buf.size() == payload.size());
+    REQUIRE(buf.capacity() == payload.size());
+
+    // Increasing the size should reallocate the buffer
+    buf.resize_destructive(payload.size() * 2);
+    REQUIRE(buf.size() == payload.size() * 2);
+    REQUIRE(buf.capacity() == payload.size() * 2);
+
+    // Since the buffer is not value initialized, reading its data will be garbage
+}
+
+TEST_CASE("ScratchBuffer: resize_destructive Shrink", "[common]") {
+    std::array<u8, 10> payload;
+    payload.fill(66);
+
+    ScratchBuffer<u8> buf(payload.size());
+    REQUIRE(buf.size() == payload.size());
+    REQUIRE(buf.capacity() == payload.size());
+
+    std::memcpy(buf.data(), payload.data(), payload.size());
+    for (size_t i = 0; i < payload.size(); ++i) {
+        REQUIRE(buf[i] == payload[i]);
+    }
+
+    // Decreasing the size should not cause a buffer reallocation
+    // This can be tested by ensuring the buffer capacity and data has not changed,
+    buf.resize_destructive(1U);
+    REQUIRE(buf.size() == 1U);
+    REQUIRE(buf.capacity() == payload.size());
+
+    for (size_t i = 0; i < payload.size(); ++i) {
+        REQUIRE(buf[i] == payload[i]);
+    }
+}
+
+TEST_CASE("ScratchBuffer: resize Grow u8", "[common]") {
+    std::array<u8, 10> payload;
+    payload.fill(66);
+
+    ScratchBuffer<u8> buf(payload.size());
+    REQUIRE(buf.size() == payload.size());
+    REQUIRE(buf.capacity() == payload.size());
+
+    std::memcpy(buf.data(), payload.data(), payload.size());
+    for (size_t i = 0; i < payload.size(); ++i) {
+        REQUIRE(buf[i] == payload[i]);
+    }
+
+    // Increasing the size should reallocate the buffer
+    buf.resize(payload.size() * 2);
+    REQUIRE(buf.size() == payload.size() * 2);
+    REQUIRE(buf.capacity() == payload.size() * 2);
+
+    // resize() keeps the previous data intact
+    for (size_t i = 0; i < payload.size(); ++i) {
+        REQUIRE(buf[i] == payload[i]);
+    }
+}
+
+TEST_CASE("ScratchBuffer: resize Grow u64", "[common]") {
+    std::array<u64, 10> payload;
+    payload.fill(6666);
+
+    ScratchBuffer<u64> buf(payload.size());
+    REQUIRE(buf.size() == payload.size());
+    REQUIRE(buf.capacity() == payload.size());
+
+    std::memcpy(buf.data(), payload.data(), payload.size() * sizeof(u64));
+    for (size_t i = 0; i < payload.size(); ++i) {
+        REQUIRE(buf[i] == payload[i]);
+    }
+
+    // Increasing the size should reallocate the buffer
+    buf.resize(payload.size() * 2);
+    REQUIRE(buf.size() == payload.size() * 2);
+    REQUIRE(buf.capacity() == payload.size() * 2);
+
+    // resize() keeps the previous data intact
+    for (size_t i = 0; i < payload.size(); ++i) {
+        REQUIRE(buf[i] == payload[i]);
+    }
+}
+
+TEST_CASE("ScratchBuffer: resize Shrink", "[common]") {
+    std::array<u8, 10> payload;
+    payload.fill(66);
+
+    ScratchBuffer<u8> buf(payload.size());
+    REQUIRE(buf.size() == payload.size());
+    REQUIRE(buf.capacity() == payload.size());
+
+    std::memcpy(buf.data(), payload.data(), payload.size());
+    for (size_t i = 0; i < payload.size(); ++i) {
+        REQUIRE(buf[i] == payload[i]);
+    }
+
+    // Decreasing the size should not cause a buffer reallocation
+    // This can be tested by ensuring the buffer capacity and data has not changed,
+    buf.resize(1U);
+    REQUIRE(buf.size() == 1U);
+    REQUIRE(buf.capacity() == payload.size());
+
+    for (size_t i = 0; i < payload.size(); ++i) {
+        REQUIRE(buf[i] == payload[i]);
+    }
+}
+
+TEST_CASE("ScratchBuffer: Span Size", "[common]") {
+    std::array<u8, 10> payload;
+    payload.fill(66);
+
+    ScratchBuffer<u8> buf(payload.size());
+    REQUIRE(buf.size() == payload.size());
+    REQUIRE(buf.capacity() == payload.size());
+
+    std::memcpy(buf.data(), payload.data(), payload.size());
+    for (size_t i = 0; i < payload.size(); ++i) {
+        REQUIRE(buf[i] == payload[i]);
+    }
+
+    buf.resize(3U);
+    REQUIRE(buf.size() == 3U);
+    REQUIRE(buf.capacity() == payload.size());
+
+    const auto buf_span = std::span<u8>(buf);
+    // The span size is the last requested size of the buffer, not its capacity
+    REQUIRE(buf_span.size() == buf.size());
+
+    for (size_t i = 0; i < buf_span.size(); ++i) {
+        REQUIRE(buf_span[i] == buf[i]);
+        REQUIRE(buf_span[i] == payload[i]);
+    }
+}
+
+TEST_CASE("ScratchBuffer: Span Writes", "[common]") {
+    std::array<u8, 10> payload;
+    payload.fill(66);
+
+    ScratchBuffer<u8> buf(payload.size());
+    REQUIRE(buf.size() == payload.size());
+    REQUIRE(buf.capacity() == payload.size());
+
+    std::memcpy(buf.data(), payload.data(), payload.size());
+    for (size_t i = 0; i < payload.size(); ++i) {
+        REQUIRE(buf[i] == payload[i]);
+    }
+
+    buf.resize(3U);
+    REQUIRE(buf.size() == 3U);
+    REQUIRE(buf.capacity() == payload.size());
+
+    const auto buf_span = std::span<u8>(buf);
+    REQUIRE(buf_span.size() == buf.size());
+
+    for (size_t i = 0; i < buf_span.size(); ++i) {
+        const auto new_value = static_cast<u8>(i + 1U);
+        // Writes to a span of the scratch buffer will propogate to the buffer itself
+        buf_span[i] = new_value;
+        REQUIRE(buf[i] == new_value);
+    }
+}
+
+} // namespace Common
diff --git a/src/video_core/buffer_cache/buffer_cache.h b/src/video_core/buffer_cache/buffer_cache.h
index 502b4d90a..6c8d98946 100644
--- a/src/video_core/buffer_cache/buffer_cache.h
+++ b/src/video_core/buffer_cache/buffer_cache.h
@@ -20,6 +20,7 @@
 #include "common/lru_cache.h"
 #include "common/microprofile.h"
 #include "common/polyfill_ranges.h"
+#include "common/scratch_buffer.h"
 #include "common/settings.h"
 #include "core/memory.h"
 #include "video_core/buffer_cache/buffer_base.h"
@@ -422,8 +423,7 @@ private:
     IntervalSet common_ranges;
     std::deque<IntervalSet> committed_ranges;
 
-    size_t immediate_buffer_capacity = 0;
-    std::unique_ptr<u8[]> immediate_buffer_alloc;
+    Common::ScratchBuffer<u8> immediate_buffer_alloc;
 
     struct LRUItemParams {
         using ObjectType = BufferId;
@@ -1926,11 +1926,8 @@ std::span<const u8> BufferCache<P>::ImmediateBufferWithData(VAddr cpu_addr, size
 
 template <class P>
 std::span<u8> BufferCache<P>::ImmediateBuffer(size_t wanted_capacity) {
-    if (wanted_capacity > immediate_buffer_capacity) {
-        immediate_buffer_capacity = wanted_capacity;
-        immediate_buffer_alloc = std::make_unique<u8[]>(wanted_capacity);
-    }
-    return std::span<u8>(immediate_buffer_alloc.get(), wanted_capacity);
+    immediate_buffer_alloc.resize_destructive(wanted_capacity);
+    return std::span<u8>(immediate_buffer_alloc.data(), wanted_capacity);
 }
 
 template <class P>
diff --git a/src/video_core/dma_pusher.cpp b/src/video_core/dma_pusher.cpp
index 9835e3ac1..322de2606 100644
--- a/src/video_core/dma_pusher.cpp
+++ b/src/video_core/dma_pusher.cpp
@@ -56,7 +56,7 @@ bool DmaPusher::Step() {
 
     if (command_list.prefetch_command_list.size()) {
         // Prefetched command list from nvdrv, used for things like synchronization
-        command_headers = std::move(command_list.prefetch_command_list);
+        ProcessCommands(command_list.prefetch_command_list);
         dma_pushbuffer.pop();
     } else {
         const CommandListHeader command_list_header{
@@ -74,7 +74,7 @@ bool DmaPusher::Step() {
         }
 
         // Push buffer non-empty, read a word
-        command_headers.resize(command_list_header.size);
+        command_headers.resize_destructive(command_list_header.size);
         if (Settings::IsGPULevelHigh()) {
             memory_manager.ReadBlock(dma_get, command_headers.data(),
                                      command_list_header.size * sizeof(u32));
@@ -82,16 +82,21 @@ bool DmaPusher::Step() {
             memory_manager.ReadBlockUnsafe(dma_get, command_headers.data(),
                                            command_list_header.size * sizeof(u32));
         }
+        ProcessCommands(command_headers);
     }
-    for (std::size_t index = 0; index < command_headers.size();) {
-        const CommandHeader& command_header = command_headers[index];
+
+    return true;
+}
+
+void DmaPusher::ProcessCommands(std::span<const CommandHeader> commands) {
+    for (std::size_t index = 0; index < commands.size();) {
+        const CommandHeader& command_header = commands[index];
 
         if (dma_state.method_count) {
             // Data word of methods command
             if (dma_state.non_incrementing) {
                 const u32 max_write = static_cast<u32>(
-                    std::min<std::size_t>(index + dma_state.method_count, command_headers.size()) -
-                    index);
+                    std::min<std::size_t>(index + dma_state.method_count, commands.size()) - index);
                 CallMultiMethod(&command_header.argument, max_write);
                 dma_state.method_count -= max_write;
                 dma_state.is_last_call = true;
@@ -142,8 +147,6 @@ bool DmaPusher::Step() {
         }
         index++;
     }
-
-    return true;
 }
 
 void DmaPusher::SetState(const CommandHeader& command_header) {
diff --git a/src/video_core/dma_pusher.h b/src/video_core/dma_pusher.h
index 938f0f11c..6f00de937 100644
--- a/src/video_core/dma_pusher.h
+++ b/src/video_core/dma_pusher.h
@@ -4,11 +4,13 @@
 #pragma once
 
 #include <array>
+#include <span>
 #include <vector>
 #include <queue>
 
 #include "common/bit_field.h"
 #include "common/common_types.h"
+#include "common/scratch_buffer.h"
 #include "video_core/engines/engine_interface.h"
 #include "video_core/engines/puller.h"
 
@@ -136,13 +138,15 @@ private:
     static constexpr u32 non_puller_methods = 0x40;
     static constexpr u32 max_subchannels = 8;
     bool Step();
+    void ProcessCommands(std::span<const CommandHeader> commands);
 
     void SetState(const CommandHeader& command_header);
 
     void CallMethod(u32 argument) const;
     void CallMultiMethod(const u32* base_start, u32 num_methods) const;
 
-    std::vector<CommandHeader> command_headers; ///< Buffer for list of commands fetched at once
+    Common::ScratchBuffer<CommandHeader>
+        command_headers; ///< Buffer for list of commands fetched at once
 
     std::queue<CommandList> dma_pushbuffer; ///< Queue of command lists to be processed
     std::size_t dma_pushbuffer_subindex{};  ///< Index within a command list within the pushbuffer
@@ -159,7 +163,7 @@ private:
     DmaState dma_state{};
     bool dma_increment_once{};
 
-    bool ib_enable{true}; ///< IB mode enabled
+    const bool ib_enable{true}; ///< IB mode enabled
 
     std::array<Engines::EngineInterface*, max_subchannels> subchannels{};
 
diff --git a/src/video_core/engines/engine_upload.cpp b/src/video_core/engines/engine_upload.cpp
index e4f8331ab..cea1dd8b0 100644
--- a/src/video_core/engines/engine_upload.cpp
+++ b/src/video_core/engines/engine_upload.cpp
@@ -24,7 +24,7 @@ void State::BindRasterizer(VideoCore::RasterizerInterface* rasterizer_) {
 void State::ProcessExec(const bool is_linear_) {
     write_offset = 0;
     copy_size = regs.line_length_in * regs.line_count;
-    inner_buffer.resize(copy_size);
+    inner_buffer.resize_destructive(copy_size);
     is_linear = is_linear_;
 }
 
@@ -70,7 +70,7 @@ void State::ProcessData(std::span<const u8> read_buffer) {
         const std::size_t dst_size = Tegra::Texture::CalculateSize(
             true, bytes_per_pixel, width, regs.dest.height, regs.dest.depth,
             regs.dest.BlockHeight(), regs.dest.BlockDepth());
-        tmp_buffer.resize(dst_size);
+        tmp_buffer.resize_destructive(dst_size);
         memory_manager.ReadBlock(address, tmp_buffer.data(), dst_size);
         Tegra::Texture::SwizzleSubrect(tmp_buffer, read_buffer, bytes_per_pixel, width,
                                        regs.dest.height, regs.dest.depth, x_offset, regs.dest.y,
diff --git a/src/video_core/engines/engine_upload.h b/src/video_core/engines/engine_upload.h
index 94fafd9dc..7242d2529 100644
--- a/src/video_core/engines/engine_upload.h
+++ b/src/video_core/engines/engine_upload.h
@@ -4,9 +4,10 @@
 #pragma once
 
 #include <span>
-#include <vector>
+
 #include "common/bit_field.h"
 #include "common/common_types.h"
+#include "common/scratch_buffer.h"
 
 namespace Tegra {
 class MemoryManager;
@@ -73,8 +74,8 @@ private:
 
     u32 write_offset = 0;
     u32 copy_size = 0;
-    std::vector<u8> inner_buffer;
-    std::vector<u8> tmp_buffer;
+    Common::ScratchBuffer<u8> inner_buffer;
+    Common::ScratchBuffer<u8> tmp_buffer;
     bool is_linear = false;
     Registers& regs;
     MemoryManager& memory_manager;
diff --git a/src/video_core/engines/maxwell_dma.cpp b/src/video_core/engines/maxwell_dma.cpp
index a189e60ae..f73d7bf0f 100644
--- a/src/video_core/engines/maxwell_dma.cpp
+++ b/src/video_core/engines/maxwell_dma.cpp
@@ -184,12 +184,8 @@ void MaxwellDMA::CopyBlockLinearToPitch() {
     const size_t src_size =
         CalculateSize(true, bytes_per_pixel, width, height, depth, block_height, block_depth);
 
-    if (read_buffer.size() < src_size) {
-        read_buffer.resize(src_size);
-    }
-    if (write_buffer.size() < dst_size) {
-        write_buffer.resize(dst_size);
-    }
+    read_buffer.resize_destructive(src_size);
+    write_buffer.resize_destructive(dst_size);
 
     memory_manager.ReadBlock(regs.offset_in, read_buffer.data(), src_size);
     memory_manager.ReadBlock(regs.offset_out, write_buffer.data(), dst_size);
@@ -235,12 +231,8 @@ void MaxwellDMA::CopyPitchToBlockLinear() {
         CalculateSize(true, bytes_per_pixel, width, height, depth, block_height, block_depth);
     const size_t src_size = static_cast<size_t>(regs.pitch_in) * regs.line_count;
 
-    if (read_buffer.size() < src_size) {
-        read_buffer.resize(src_size);
-    }
-    if (write_buffer.size() < dst_size) {
-        write_buffer.resize(dst_size);
-    }
+    read_buffer.resize_destructive(src_size);
+    write_buffer.resize_destructive(dst_size);
 
     memory_manager.ReadBlock(regs.offset_in, read_buffer.data(), src_size);
     if (Settings::IsGPULevelExtreme()) {
@@ -269,12 +261,8 @@ void MaxwellDMA::FastCopyBlockLinearToPitch() {
     pos_x = pos_x % x_in_gob;
     pos_y = pos_y % 8;
 
-    if (read_buffer.size() < src_size) {
-        read_buffer.resize(src_size);
-    }
-    if (write_buffer.size() < dst_size) {
-        write_buffer.resize(dst_size);
-    }
+    read_buffer.resize_destructive(src_size);
+    write_buffer.resize_destructive(dst_size);
 
     if (Settings::IsGPULevelExtreme()) {
         memory_manager.ReadBlock(regs.offset_in + offset, read_buffer.data(), src_size);
@@ -333,14 +321,10 @@ void MaxwellDMA::CopyBlockLinearToBlockLinear() {
     const u32 pitch = x_elements * bytes_per_pixel;
     const size_t mid_buffer_size = pitch * regs.line_count;
 
-    if (read_buffer.size() < src_size) {
-        read_buffer.resize(src_size);
-    }
-    if (write_buffer.size() < dst_size) {
-        write_buffer.resize(dst_size);
-    }
+    read_buffer.resize_destructive(src_size);
+    write_buffer.resize_destructive(dst_size);
 
-    intermediate_buffer.resize(mid_buffer_size);
+    intermediate_buffer.resize_destructive(mid_buffer_size);
 
     memory_manager.ReadBlock(regs.offset_in, read_buffer.data(), src_size);
     memory_manager.ReadBlock(regs.offset_out, write_buffer.data(), dst_size);
diff --git a/src/video_core/engines/maxwell_dma.h b/src/video_core/engines/maxwell_dma.h
index d40d3d302..c88191a61 100644
--- a/src/video_core/engines/maxwell_dma.h
+++ b/src/video_core/engines/maxwell_dma.h
@@ -6,8 +6,10 @@
 #include <array>
 #include <cstddef>
 #include <vector>
+
 #include "common/bit_field.h"
 #include "common/common_types.h"
+#include "common/scratch_buffer.h"
 #include "video_core/engines/engine_interface.h"
 
 namespace Core {
@@ -234,9 +236,9 @@ private:
     MemoryManager& memory_manager;
     VideoCore::RasterizerInterface* rasterizer = nullptr;
 
-    std::vector<u8> read_buffer;
-    std::vector<u8> write_buffer;
-    std::vector<u8> intermediate_buffer;
+    Common::ScratchBuffer<u8> read_buffer;
+    Common::ScratchBuffer<u8> write_buffer;
+    Common::ScratchBuffer<u8> intermediate_buffer;
 
     static constexpr std::size_t NUM_REGS = 0x800;
     struct Regs {
diff --git a/src/video_core/host1x/vic.cpp b/src/video_core/host1x/vic.cpp
index ac0b7d20e..36a04e4e0 100644
--- a/src/video_core/host1x/vic.cpp
+++ b/src/video_core/host1x/vic.cpp
@@ -155,7 +155,7 @@ void Vic::WriteRGBFrame(const AVFrame* frame, const VicConfig& config) {
         // swizzle pitch linear to block linear
         const u32 block_height = static_cast<u32>(config.block_linear_height_log2);
         const auto size = Texture::CalculateSize(true, 4, width, height, 1, block_height, 0);
-        luma_buffer.resize(size);
+        luma_buffer.resize_destructive(size);
         std::span<const u8> frame_buff(converted_frame_buf_addr, 4 * width * height);
         Texture::SwizzleSubrect(luma_buffer, frame_buff, 4, width, height, 1, 0, 0, width, height,
                                 block_height, 0, width * 4);
@@ -181,8 +181,8 @@ void Vic::WriteYUVFrame(const AVFrame* frame, const VicConfig& config) {
 
     const auto stride = static_cast<size_t>(frame->linesize[0]);
 
-    luma_buffer.resize(aligned_width * surface_height);
-    chroma_buffer.resize(aligned_width * surface_height / 2);
+    luma_buffer.resize_destructive(aligned_width * surface_height);
+    chroma_buffer.resize_destructive(aligned_width * surface_height / 2);
 
     // Populate luma buffer
     const u8* luma_src = frame->data[0];
diff --git a/src/video_core/host1x/vic.h b/src/video_core/host1x/vic.h
index 2b78786e8..3d9753047 100644
--- a/src/video_core/host1x/vic.h
+++ b/src/video_core/host1x/vic.h
@@ -4,8 +4,9 @@
 #pragma once
 
 #include <memory>
-#include <vector>
+
 #include "common/common_types.h"
+#include "common/scratch_buffer.h"
 
 struct SwsContext;
 
@@ -49,8 +50,8 @@ private:
     /// size does not change during a stream
     using AVMallocPtr = std::unique_ptr<u8, decltype(&av_free)>;
     AVMallocPtr converted_frame_buffer;
-    std::vector<u8> luma_buffer;
-    std::vector<u8> chroma_buffer;
+    Common::ScratchBuffer<u8> luma_buffer;
+    Common::ScratchBuffer<u8> chroma_buffer;
 
     GPUVAddr config_struct_address{};
     GPUVAddr output_surface_luma_address{};