1 files changed, 355 insertions, 127 deletions

diff --git a/src/video_core/memory_manager.cpp b/src/video_core/memory_manager.cpp
index 8e8f36f28..e76b59842 100644
--- a/src/video_core/memory_manager.cpp
+++ b/src/video_core/memory_manager.cpp
@@ -5,218 +5,446 @@
 #include "common/alignment.h"
 #include "common/assert.h"
 #include "common/logging/log.h"
+#include "core/core.h"
 #include "core/memory.h"
+#include "video_core/gpu.h"
 #include "video_core/memory_manager.h"
+#include "video_core/rasterizer_interface.h"
+#include "video_core/renderer_base.h"
 
 namespace Tegra {
 
 MemoryManager::MemoryManager() {
-    // Mark the first page as reserved, so that 0 is not a valid GPUVAddr. Otherwise, games might
-    // try to use 0 as a valid address, which is also used to mean nullptr. This fixes a bug with
-    // Undertale using 0 for a render target.
-    PageSlot(0) = static_cast<u64>(PageStatus::Reserved);
-}
-
-GPUVAddr MemoryManager::AllocateSpace(u64 size, u64 align) {
-    const std::optional<GPUVAddr> gpu_addr{FindFreeBlock(0, size, align, PageStatus::Unmapped)};
+    std::fill(page_table.pointers.begin(), page_table.pointers.end(), nullptr);
+    std::fill(page_table.attributes.begin(), page_table.attributes.end(),
+              Common::PageType::Unmapped);
+    page_table.Resize(address_space_width);
 
-    ASSERT_MSG(gpu_addr, "unable to find available GPU memory");
+    // Initialize the map with a single free region covering the entire managed space.
+    VirtualMemoryArea initial_vma;
+    initial_vma.size = address_space_end;
+    vma_map.emplace(initial_vma.base, initial_vma);
 
-    for (u64 offset{}; offset < size; offset += PAGE_SIZE) {
-        VAddr& slot{PageSlot(*gpu_addr + offset)};
+    UpdatePageTableForVMA(initial_vma);
+}
 
-        ASSERT(slot == static_cast<u64>(PageStatus::Unmapped));
+GPUVAddr MemoryManager::AllocateSpace(u64 size, u64 align) {
+    const u64 aligned_size{Common::AlignUp(size, page_size)};
+    const GPUVAddr gpu_addr{FindFreeRegion(address_space_base, aligned_size)};
 
-        slot = static_cast<u64>(PageStatus::Allocated);
-    }
+    AllocateMemory(gpu_addr, 0, aligned_size);
 
-    return *gpu_addr;
+    return gpu_addr;
 }
 
 GPUVAddr MemoryManager::AllocateSpace(GPUVAddr gpu_addr, u64 size, u64 align) {
-    for (u64 offset{}; offset < size; offset += PAGE_SIZE) {
-        VAddr& slot{PageSlot(gpu_addr + offset)};
+    const u64 aligned_size{Common::AlignUp(size, page_size)};
 
-        ASSERT(slot == static_cast<u64>(PageStatus::Unmapped));
-
-        slot = static_cast<u64>(PageStatus::Allocated);
-    }
+    AllocateMemory(gpu_addr, 0, aligned_size);
 
     return gpu_addr;
 }
 
 GPUVAddr MemoryManager::MapBufferEx(VAddr cpu_addr, u64 size) {
-    const std::optional<GPUVAddr> gpu_addr{FindFreeBlock(0, size, PAGE_SIZE, PageStatus::Unmapped)};
+    const u64 aligned_size{Common::AlignUp(size, page_size)};
+    const GPUVAddr gpu_addr{FindFreeRegion(address_space_base, aligned_size)};
 
-    ASSERT_MSG(gpu_addr, "unable to find available GPU memory");
+    MapBackingMemory(gpu_addr, Memory::GetPointer(cpu_addr), aligned_size, cpu_addr);
 
-    for (u64 offset{}; offset < size; offset += PAGE_SIZE) {
-        VAddr& slot{PageSlot(*gpu_addr + offset)};
+    return gpu_addr;
+}
 
-        ASSERT(slot == static_cast<u64>(PageStatus::Unmapped));
+GPUVAddr MemoryManager::MapBufferEx(VAddr cpu_addr, GPUVAddr gpu_addr, u64 size) {
+    ASSERT((gpu_addr & page_mask) == 0);
 
-        slot = cpu_addr + offset;
-    }
+    const u64 aligned_size{Common::AlignUp(size, page_size)};
 
-    const MappedRegion region{cpu_addr, *gpu_addr, size};
-    mapped_regions.push_back(region);
+    MapBackingMemory(gpu_addr, Memory::GetPointer(cpu_addr), aligned_size, cpu_addr);
 
-    return *gpu_addr;
+    return gpu_addr;
 }
 
-GPUVAddr MemoryManager::MapBufferEx(VAddr cpu_addr, GPUVAddr gpu_addr, u64 size) {
-    ASSERT((gpu_addr & PAGE_MASK) == 0);
+GPUVAddr MemoryManager::UnmapBuffer(GPUVAddr gpu_addr, u64 size) {
+    ASSERT((gpu_addr & page_mask) == 0);
 
-    if (PageSlot(gpu_addr) != static_cast<u64>(PageStatus::Allocated)) {
-        // Page has been already mapped. In this case, we must find a new area of memory to use that
-        // is different than the specified one. Super Mario Odyssey hits this scenario when changing
-        // areas, but we do not want to overwrite the old pages.
-        // TODO(bunnei): We need to write a hardware test to confirm this behavior.
+    const u64 aligned_size{Common::AlignUp(size, page_size)};
+    const CacheAddr cache_addr{ToCacheAddr(GetPointer(gpu_addr))};
 
-        LOG_ERROR(HW_GPU, "attempting to map addr 0x{:016X}, which is not available!", gpu_addr);
+    Core::System::GetInstance().Renderer().Rasterizer().FlushAndInvalidateRegion(cache_addr,
+                                                                                 aligned_size);
+    UnmapRange(gpu_addr, aligned_size);
 
-        const std::optional<GPUVAddr> new_gpu_addr{
-            FindFreeBlock(gpu_addr, size, PAGE_SIZE, PageStatus::Allocated)};
+    return gpu_addr;
+}
 
-        ASSERT_MSG(new_gpu_addr, "unable to find available GPU memory");
+GPUVAddr MemoryManager::FindFreeRegion(GPUVAddr region_start, u64 size) {
+    // Find the first Free VMA.
+    const VMAHandle vma_handle{std::find_if(vma_map.begin(), vma_map.end(), [&](const auto& vma) {
+        if (vma.second.type != VirtualMemoryArea::Type::Unmapped) {
+            return false;
+        }
 
-        gpu_addr = *new_gpu_addr;
+        const VAddr vma_end{vma.second.base + vma.second.size};
+        return vma_end > region_start && vma_end >= region_start + size;
+    })};
+
+    if (vma_handle == vma_map.end()) {
+        return {};
     }
 
-    for (u64 offset{}; offset < size; offset += PAGE_SIZE) {
-        VAddr& slot{PageSlot(gpu_addr + offset)};
+    return std::max(region_start, vma_handle->second.base);
+}
 
-        ASSERT(slot == static_cast<u64>(PageStatus::Allocated));
+bool MemoryManager::IsAddressValid(GPUVAddr addr) const {
+    return (addr >> page_bits) < page_table.pointers.size();
+}
 
-        slot = cpu_addr + offset;
+std::optional<VAddr> MemoryManager::GpuToCpuAddress(GPUVAddr addr) {
+    if (!IsAddressValid(addr)) {
+        return {};
     }
 
-    const MappedRegion region{cpu_addr, gpu_addr, size};
-    mapped_regions.push_back(region);
+    VAddr cpu_addr{page_table.backing_addr[addr >> page_bits]};
+    if (cpu_addr) {
+        return cpu_addr + (addr & page_mask);
+    }
 
-    return gpu_addr;
+    return {};
 }
 
-GPUVAddr MemoryManager::UnmapBuffer(GPUVAddr gpu_addr, u64 size) {
-    ASSERT((gpu_addr & PAGE_MASK) == 0);
+template <typename T>
+T MemoryManager::Read(GPUVAddr addr) {
+    if (!IsAddressValid(addr)) {
+        return {};
+    }
 
-    for (u64 offset{}; offset < size; offset += PAGE_SIZE) {
-        VAddr& slot{PageSlot(gpu_addr + offset)};
+    const u8* page_pointer{page_table.pointers[addr >> page_bits]};
+    if (page_pointer) {
+        // NOTE: Avoid adding any extra logic to this fast-path block
+        T value;
+        std::memcpy(&value, &page_pointer[addr & page_mask], sizeof(T));
+        return value;
+    }
 
-        ASSERT(slot != static_cast<u64>(PageStatus::Allocated) &&
-               slot != static_cast<u64>(PageStatus::Unmapped));
+    switch (page_table.attributes[addr >> page_bits]) {
+    case Common::PageType::Unmapped:
+        LOG_ERROR(HW_GPU, "Unmapped Read{} @ 0x{:08X}", sizeof(T) * 8, addr);
+        return 0;
+    case Common::PageType::Memory:
+        ASSERT_MSG(false, "Mapped memory page without a pointer @ {:016X}", addr);
+        break;
+    default:
+        UNREACHABLE();
+    }
+    return {};
+}
 
-        slot = static_cast<u64>(PageStatus::Unmapped);
+template <typename T>
+void MemoryManager::Write(GPUVAddr addr, T data) {
+    if (!IsAddressValid(addr)) {
+        return;
     }
 
-    // Delete the region mappings that are contained within the unmapped region
-    mapped_regions.erase(std::remove_if(mapped_regions.begin(), mapped_regions.end(),
-                                        [&](const MappedRegion& region) {
-                                            return region.gpu_addr <= gpu_addr &&
-                                                   region.gpu_addr + region.size < gpu_addr + size;
-                                        }),
-                         mapped_regions.end());
-    return gpu_addr;
-}
+    u8* page_pointer{page_table.pointers[addr >> page_bits]};
+    if (page_pointer) {
+        // NOTE: Avoid adding any extra logic to this fast-path block
+        std::memcpy(&page_pointer[addr & page_mask], &data, sizeof(T));
+        return;
+    }
 
-GPUVAddr MemoryManager::GetRegionEnd(GPUVAddr region_start) const {
-    for (const auto& region : mapped_regions) {
-        const GPUVAddr region_end{region.gpu_addr + region.size};
-        if (region_start >= region.gpu_addr && region_start < region_end) {
-            return region_end;
-        }
+    switch (page_table.attributes[addr >> page_bits]) {
+    case Common::PageType::Unmapped:
+        LOG_ERROR(HW_GPU, "Unmapped Write{} 0x{:08X} @ 0x{:016X}", sizeof(data) * 8,
+                  static_cast<u32>(data), addr);
+        return;
+    case Common::PageType::Memory:
+        ASSERT_MSG(false, "Mapped memory page without a pointer @ {:016X}", addr);
+        break;
+    default:
+        UNREACHABLE();
     }
-    return {};
 }
 
-std::optional<GPUVAddr> MemoryManager::FindFreeBlock(GPUVAddr region_start, u64 size, u64 align,
-                                                     PageStatus status) {
-    GPUVAddr gpu_addr{region_start};
-    u64 free_space{};
-    align = (align + PAGE_MASK) & ~PAGE_MASK;
-
-    while (gpu_addr + free_space < MAX_ADDRESS) {
-        if (PageSlot(gpu_addr + free_space) == static_cast<u64>(status)) {
-            free_space += PAGE_SIZE;
-            if (free_space >= size) {
-                return gpu_addr;
-            }
-        } else {
-            gpu_addr += free_space + PAGE_SIZE;
-            free_space = 0;
-            gpu_addr = Common::AlignUp(gpu_addr, align);
-        }
+template u8 MemoryManager::Read<u8>(GPUVAddr addr);
+template u16 MemoryManager::Read<u16>(GPUVAddr addr);
+template u32 MemoryManager::Read<u32>(GPUVAddr addr);
+template u64 MemoryManager::Read<u64>(GPUVAddr addr);
+template void MemoryManager::Write<u8>(GPUVAddr addr, u8 data);
+template void MemoryManager::Write<u16>(GPUVAddr addr, u16 data);
+template void MemoryManager::Write<u32>(GPUVAddr addr, u32 data);
+template void MemoryManager::Write<u64>(GPUVAddr addr, u64 data);
+
+u8* MemoryManager::GetPointer(GPUVAddr addr) {
+    if (!IsAddressValid(addr)) {
+        return {};
     }
 
+    u8* page_pointer{page_table.pointers[addr >> page_bits]};
+    if (page_pointer) {
+        return page_pointer + (addr & page_mask);
+    }
+
+    LOG_ERROR(HW_GPU, "Unknown GetPointer @ 0x{:016X}", addr);
     return {};
 }
 
-std::optional<VAddr> MemoryManager::GpuToCpuAddress(GPUVAddr gpu_addr) {
-    const VAddr base_addr{PageSlot(gpu_addr)};
+void MemoryManager::ReadBlock(GPUVAddr src_addr, void* dest_buffer, std::size_t size) {
+    std::memcpy(dest_buffer, GetPointer(src_addr), size);
+}
+void MemoryManager::WriteBlock(GPUVAddr dest_addr, const void* src_buffer, std::size_t size) {
+    std::memcpy(GetPointer(dest_addr), src_buffer, size);
+}
+
+void MemoryManager::CopyBlock(GPUVAddr dest_addr, GPUVAddr src_addr, std::size_t size) {
+    std::memcpy(GetPointer(dest_addr), GetPointer(src_addr), size);
+}
 
-    if (base_addr == static_cast<u64>(PageStatus::Allocated) ||
-        base_addr == static_cast<u64>(PageStatus::Unmapped) ||
-        base_addr == static_cast<u64>(PageStatus::Reserved)) {
-        return {};
+void MemoryManager::MapPages(GPUVAddr base, u64 size, u8* memory, Common::PageType type,
+                             VAddr backing_addr) {
+    LOG_DEBUG(HW_GPU, "Mapping {} onto {:016X}-{:016X}", fmt::ptr(memory), base * page_size,
+              (base + size) * page_size);
+
+    const VAddr end{base + size};
+    ASSERT_MSG(end <= page_table.pointers.size(), "out of range mapping at {:016X}",
+               base + page_table.pointers.size());
+
+    std::fill(page_table.attributes.begin() + base, page_table.attributes.begin() + end, type);
+
+    if (memory == nullptr) {
+        std::fill(page_table.pointers.begin() + base, page_table.pointers.begin() + end, memory);
+        std::fill(page_table.backing_addr.begin() + base, page_table.backing_addr.begin() + end,
+                  backing_addr);
+    } else {
+        while (base != end) {
+            page_table.pointers[base] = memory;
+            page_table.backing_addr[base] = backing_addr;
+
+            base += 1;
+            memory += page_size;
+            backing_addr += page_size;
+        }
     }
+}
 
-    return base_addr + (gpu_addr & PAGE_MASK);
+void MemoryManager::MapMemoryRegion(GPUVAddr base, u64 size, u8* target, VAddr backing_addr) {
+    ASSERT_MSG((size & page_mask) == 0, "non-page aligned size: {:016X}", size);
+    ASSERT_MSG((base & page_mask) == 0, "non-page aligned base: {:016X}", base);
+    MapPages(base / page_size, size / page_size, target, Common::PageType::Memory, backing_addr);
 }
 
-u8 MemoryManager::Read8(GPUVAddr addr) {
-    return Memory::Read8(*GpuToCpuAddress(addr));
+void MemoryManager::UnmapRegion(GPUVAddr base, u64 size) {
+    ASSERT_MSG((size & page_mask) == 0, "non-page aligned size: {:016X}", size);
+    ASSERT_MSG((base & page_mask) == 0, "non-page aligned base: {:016X}", base);
+    MapPages(base / page_size, size / page_size, nullptr, Common::PageType::Unmapped);
 }
 
-u16 MemoryManager::Read16(GPUVAddr addr) {
-    return Memory::Read16(*GpuToCpuAddress(addr));
+bool VirtualMemoryArea::CanBeMergedWith(const VirtualMemoryArea& next) const {
+    ASSERT(base + size == next.base);
+    if (type != next.type) {
+        return {};
+    }
+    if (type == VirtualMemoryArea::Type::Allocated && (offset + size != next.offset)) {
+        return {};
+    }
+    if (type == VirtualMemoryArea::Type::Mapped && backing_memory + size != next.backing_memory) {
+        return {};
+    }
+    return true;
 }
 
-u32 MemoryManager::Read32(GPUVAddr addr) {
-    return Memory::Read32(*GpuToCpuAddress(addr));
+MemoryManager::VMAHandle MemoryManager::FindVMA(GPUVAddr target) const {
+    if (target >= address_space_end) {
+        return vma_map.end();
+    } else {
+        return std::prev(vma_map.upper_bound(target));
+    }
 }
 
-u64 MemoryManager::Read64(GPUVAddr addr) {
-    return Memory::Read64(*GpuToCpuAddress(addr));
+MemoryManager::VMAIter MemoryManager::Allocate(VMAIter vma_handle) {
+    VirtualMemoryArea& vma{vma_handle->second};
+
+    vma.type = VirtualMemoryArea::Type::Allocated;
+    vma.backing_addr = 0;
+    vma.backing_memory = {};
+    UpdatePageTableForVMA(vma);
+
+    return MergeAdjacent(vma_handle);
 }
 
-void MemoryManager::Write8(GPUVAddr addr, u8 data) {
-    Memory::Write8(*GpuToCpuAddress(addr), data);
+MemoryManager::VMAHandle MemoryManager::AllocateMemory(GPUVAddr target, std::size_t offset,
+                                                       u64 size) {
+
+    // This is the appropriately sized VMA that will turn into our allocation.
+    VMAIter vma_handle{CarveVMA(target, size)};
+    VirtualMemoryArea& vma{vma_handle->second};
+
+    ASSERT(vma.size == size);
+
+    vma.offset = offset;
+
+    return Allocate(vma_handle);
 }
 
-void MemoryManager::Write16(GPUVAddr addr, u16 data) {
-    Memory::Write16(*GpuToCpuAddress(addr), data);
+MemoryManager::VMAHandle MemoryManager::MapBackingMemory(GPUVAddr target, u8* memory, u64 size,
+                                                         VAddr backing_addr) {
+    // This is the appropriately sized VMA that will turn into our allocation.
+    VMAIter vma_handle{CarveVMA(target, size)};
+    VirtualMemoryArea& vma{vma_handle->second};
+
+    ASSERT(vma.size == size);
+
+    vma.type = VirtualMemoryArea::Type::Mapped;
+    vma.backing_memory = memory;
+    vma.backing_addr = backing_addr;
+    UpdatePageTableForVMA(vma);
+
+    return MergeAdjacent(vma_handle);
 }
 
-void MemoryManager::Write32(GPUVAddr addr, u32 data) {
-    Memory::Write32(*GpuToCpuAddress(addr), data);
+void MemoryManager::UnmapRange(GPUVAddr target, u64 size) {
+    VMAIter vma{CarveVMARange(target, size)};
+    const VAddr target_end{target + size};
+    const VMAIter end{vma_map.end()};
+
+    // The comparison against the end of the range must be done using addresses since VMAs can be
+    // merged during this process, causing invalidation of the iterators.
+    while (vma != end && vma->second.base < target_end) {
+        // Unmapped ranges return to allocated state and can be reused
+        // This behavior is used by Super Mario Odyssey, Sonic Forces, and likely other games
+        vma = std::next(Allocate(vma));
+    }
+
+    ASSERT(FindVMA(target)->second.size >= size);
 }
 
-void MemoryManager::Write64(GPUVAddr addr, u64 data) {
-    Memory::Write64(*GpuToCpuAddress(addr), data);
+MemoryManager::VMAIter MemoryManager::StripIterConstness(const VMAHandle& iter) {
+    // This uses a neat C++ trick to convert a const_iterator to a regular iterator, given
+    // non-const access to its container.
+    return vma_map.erase(iter, iter); // Erases an empty range of elements
 }
 
-u8* MemoryManager::GetPointer(GPUVAddr addr) {
-    return Memory::GetPointer(*GpuToCpuAddress(addr));
+MemoryManager::VMAIter MemoryManager::CarveVMA(GPUVAddr base, u64 size) {
+    ASSERT_MSG((size & page_mask) == 0, "non-page aligned size: 0x{:016X}", size);
+    ASSERT_MSG((base & page_mask) == 0, "non-page aligned base: 0x{:016X}", base);
+
+    VMAIter vma_handle{StripIterConstness(FindVMA(base))};
+    if (vma_handle == vma_map.end()) {
+        // Target address is outside the managed range
+        return {};
+    }
+
+    const VirtualMemoryArea& vma{vma_handle->second};
+    if (vma.type == VirtualMemoryArea::Type::Mapped) {
+        // Region is already allocated
+        return {};
+    }
+
+    const VAddr start_in_vma{base - vma.base};
+    const VAddr end_in_vma{start_in_vma + size};
+
+    ASSERT_MSG(end_in_vma <= vma.size, "region size 0x{:016X} is less than required size 0x{:016X}",
+               vma.size, end_in_vma);
+
+    if (end_in_vma < vma.size) {
+        // Split VMA at the end of the allocated region
+        SplitVMA(vma_handle, end_in_vma);
+    }
+    if (start_in_vma != 0) {
+        // Split VMA at the start of the allocated region
+        vma_handle = SplitVMA(vma_handle, start_in_vma);
+    }
+
+    return vma_handle;
 }
 
-void MemoryManager::ReadBlock(GPUVAddr src_addr, void* dest_buffer, std::size_t size) {
-    std::memcpy(dest_buffer, GetPointer(src_addr), size);
+MemoryManager::VMAIter MemoryManager::CarveVMARange(GPUVAddr target, u64 size) {
+    ASSERT_MSG((size & page_mask) == 0, "non-page aligned size: 0x{:016X}", size);
+    ASSERT_MSG((target & page_mask) == 0, "non-page aligned base: 0x{:016X}", target);
+
+    const VAddr target_end{target + size};
+    ASSERT(target_end >= target);
+    ASSERT(size > 0);
+
+    VMAIter begin_vma{StripIterConstness(FindVMA(target))};
+    const VMAIter i_end{vma_map.lower_bound(target_end)};
+    if (std::any_of(begin_vma, i_end, [](const auto& entry) {
+            return entry.second.type == VirtualMemoryArea::Type::Unmapped;
+        })) {
+        return {};
+    }
+
+    if (target != begin_vma->second.base) {
+        begin_vma = SplitVMA(begin_vma, target - begin_vma->second.base);
+    }
+
+    VMAIter end_vma{StripIterConstness(FindVMA(target_end))};
+    if (end_vma != vma_map.end() && target_end != end_vma->second.base) {
+        end_vma = SplitVMA(end_vma, target_end - end_vma->second.base);
+    }
+
+    return begin_vma;
 }
-void MemoryManager::WriteBlock(GPUVAddr dest_addr, const void* src_buffer, std::size_t size) {
-    std::memcpy(GetPointer(dest_addr), src_buffer, size);
+
+MemoryManager::VMAIter MemoryManager::SplitVMA(VMAIter vma_handle, u64 offset_in_vma) {
+    VirtualMemoryArea& old_vma{vma_handle->second};
+    VirtualMemoryArea new_vma{old_vma}; // Make a copy of the VMA
+
+    // For now, don't allow no-op VMA splits (trying to split at a boundary) because it's probably
+    // a bug. This restriction might be removed later.
+    ASSERT(offset_in_vma < old_vma.size);
+    ASSERT(offset_in_vma > 0);
+
+    old_vma.size = offset_in_vma;
+    new_vma.base += offset_in_vma;
+    new_vma.size -= offset_in_vma;
+
+    switch (new_vma.type) {
+    case VirtualMemoryArea::Type::Unmapped:
+        break;
+    case VirtualMemoryArea::Type::Allocated:
+        new_vma.offset += offset_in_vma;
+        break;
+    case VirtualMemoryArea::Type::Mapped:
+        new_vma.backing_memory += offset_in_vma;
+        break;
+    }
+
+    ASSERT(old_vma.CanBeMergedWith(new_vma));
+
+    return vma_map.emplace_hint(std::next(vma_handle), new_vma.base, new_vma);
 }
 
-void MemoryManager::CopyBlock(GPUVAddr dest_addr, GPUVAddr src_addr, std::size_t size) {
-    std::memcpy(GetPointer(dest_addr), GetPointer(src_addr), size);
+MemoryManager::VMAIter MemoryManager::MergeAdjacent(VMAIter iter) {
+    const VMAIter next_vma{std::next(iter)};
+    if (next_vma != vma_map.end() && iter->second.CanBeMergedWith(next_vma->second)) {
+        iter->second.size += next_vma->second.size;
+        vma_map.erase(next_vma);
+    }
+
+    if (iter != vma_map.begin()) {
+        VMAIter prev_vma{std::prev(iter)};
+        if (prev_vma->second.CanBeMergedWith(iter->second)) {
+            prev_vma->second.size += iter->second.size;
+            vma_map.erase(iter);
+            iter = prev_vma;
+        }
+    }
+
+    return iter;
 }
 
-VAddr& MemoryManager::PageSlot(GPUVAddr gpu_addr) {
-    auto& block{page_table[(gpu_addr >> (PAGE_BITS + PAGE_TABLE_BITS)) & PAGE_TABLE_MASK]};
-    if (!block) {
-        block = std::make_unique<PageBlock>();
-        block->fill(static_cast<VAddr>(PageStatus::Unmapped));
+void MemoryManager::UpdatePageTableForVMA(const VirtualMemoryArea& vma) {
+    switch (vma.type) {
+    case VirtualMemoryArea::Type::Unmapped:
+        UnmapRegion(vma.base, vma.size);
+        break;
+    case VirtualMemoryArea::Type::Allocated:
+        MapMemoryRegion(vma.base, vma.size, nullptr, vma.backing_addr);
+        break;
+    case VirtualMemoryArea::Type::Mapped:
+        MapMemoryRegion(vma.base, vma.size, vma.backing_memory, vma.backing_addr);
+        break;
     }
-    return (*block)[(gpu_addr >> PAGE_BITS) & PAGE_BLOCK_MASK];
 }
 
 } // namespace Tegra