1 files changed, 947 insertions, 0 deletions
diff --git a/Ryujinx.Cpu/AppleHv/HvMemoryManager.cs b/Ryujinx.Cpu/AppleHv/HvMemoryManager.cs
new file mode 100644
index 00000000..222dcae1
--- /dev/null
+++ b/Ryujinx.Cpu/AppleHv/HvMemoryManager.cs
@@ -0,0 +1,947 @@
+using ARMeilleure.Memory;
+using Ryujinx.Cpu.Tracking;
+using Ryujinx.Memory;
+using Ryujinx.Memory.Range;
+using Ryujinx.Memory.Tracking;
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Runtime.CompilerServices;
+using System.Runtime.InteropServices;
+using System.Threading;
+
+namespace Ryujinx.Cpu.AppleHv
+{
+    /// <summary>
+    /// Represents a CPU memory manager which maps guest virtual memory directly onto the Hypervisor page table.
+    /// </summary>
+    public class HvMemoryManager : MemoryManagerBase, IMemoryManager, IVirtualMemoryManagerTracked, IWritableBlock
+    {
+        public const int PageBits = 12;
+        public const int PageSize = 1 << PageBits;
+        public const int PageMask = PageSize - 1;
+
+        public const int PageToPteShift = 5; // 32 pages (2 bits each) in one ulong page table entry.
+        public const ulong BlockMappedMask = 0x5555555555555555; // First bit of each table entry set.
+
+        private enum HostMappedPtBits : ulong
+        {
+            Unmapped = 0,
+            Mapped,
+            WriteTracked,
+            ReadWriteTracked,
+
+            MappedReplicated = 0x5555555555555555,
+            WriteTrackedReplicated = 0xaaaaaaaaaaaaaaaa,
+            ReadWriteTrackedReplicated = ulong.MaxValue
+        }
+
+        private readonly InvalidAccessHandler _invalidAccessHandler;
+
+        private readonly ulong _addressSpaceSize;
+
+        private readonly HvAddressSpace _addressSpace;
+
+        internal HvAddressSpace AddressSpace => _addressSpace;
+
+        private readonly MemoryBlock _backingMemory;
+        private readonly PageTable<ulong> _pageTable;
+
+        private readonly ulong[] _pageBitmap;
+
+        public bool Supports4KBPages => true;
+
+        public int AddressSpaceBits { get; }
+
+        public IntPtr PageTablePointer => IntPtr.Zero;
+
+        public MemoryManagerType Type => MemoryManagerType.SoftwarePageTable;
+
+        public MemoryTracking Tracking { get; }
+
+        public event Action<ulong, ulong> UnmapEvent;
+
+        /// <summary>
+        /// Creates a new instance of the Hypervisor memory manager.
+        /// </summary>
+        /// <param name="backingMemory">Physical backing memory where virtual memory will be mapped to</param>
+        /// <param name="addressSpaceSize">Size of the address space</param>
+        /// <param name="invalidAccessHandler">Optional function to handle invalid memory accesses</param>
+        public HvMemoryManager(MemoryBlock backingMemory, ulong addressSpaceSize, InvalidAccessHandler invalidAccessHandler = null)
+        {
+            _backingMemory = backingMemory;
+            _pageTable = new PageTable<ulong>();
+            _invalidAccessHandler = invalidAccessHandler;
+            _addressSpaceSize = addressSpaceSize;
+
+            ulong asSize = PageSize;
+            int asBits = PageBits;
+
+            while (asSize < addressSpaceSize)
+            {
+                asSize <<= 1;
+                asBits++;
+            }
+
+            _addressSpace = new HvAddressSpace(backingMemory, asSize);
+
+            AddressSpaceBits = asBits;
+
+            _pageBitmap = new ulong[1 << (AddressSpaceBits - (PageBits + PageToPteShift))];
+            Tracking = new MemoryTracking(this, PageSize, invalidAccessHandler);
+        }
+
+        /// <summary>
+        /// Checks if the virtual address is part of the addressable space.
+        /// </summary>
+        /// <param name="va">Virtual address</param>
+        /// <returns>True if the virtual address is part of the addressable space</returns>
+        private bool ValidateAddress(ulong va)
+        {
+            return va < _addressSpaceSize;
+        }
+
+        /// <summary>
+        /// Checks if the combination of virtual address and size is part of the addressable space.
+        /// </summary>
+        /// <param name="va">Virtual address of the range</param>
+        /// <param name="size">Size of the range in bytes</param>
+        /// <returns>True if the combination of virtual address and size is part of the addressable space</returns>
+        private bool ValidateAddressAndSize(ulong va, ulong size)
+        {
+            ulong endVa = va + size;
+            return endVa >= va && endVa >= size && endVa <= _addressSpaceSize;
+        }
+
+        /// <summary>
+        /// Ensures the combination of virtual address and size is part of the addressable space.
+        /// </summary>
+        /// <param name="va">Virtual address of the range</param>
+        /// <param name="size">Size of the range in bytes</param>
+        /// <exception cref="InvalidMemoryRegionException">Throw when the memory region specified outside the addressable space</exception>
+        private void AssertValidAddressAndSize(ulong va, ulong size)
+        {
+            if (!ValidateAddressAndSize(va, size))
+            {
+                throw new InvalidMemoryRegionException($"va=0x{va:X16}, size=0x{size:X16}");
+            }
+        }
+
+        /// <summary>
+        /// Ensures the combination of virtual address and size is part of the addressable space and fully mapped.
+        /// </summary>
+        /// <param name="va">Virtual address of the range</param>
+        /// <param name="size">Size of the range in bytes</param>
+        private void AssertMapped(ulong va, ulong size)
+        {
+            if (!ValidateAddressAndSize(va, size) || !IsRangeMappedImpl(va, size))
+            {
+                throw new InvalidMemoryRegionException($"Not mapped: va=0x{va:X16}, size=0x{size:X16}");
+            }
+        }
+
+        /// <inheritdoc/>
+        public void Map(ulong va, ulong pa, ulong size, MemoryMapFlags flags)
+        {
+            AssertValidAddressAndSize(va, size);
+
+            PtMap(va, pa, size);
+            _addressSpace.MapUser(va, pa, size, MemoryPermission.ReadWriteExecute);
+            AddMapping(va, size);
+
+            Tracking.Map(va, size);
+        }
+
+        private void PtMap(ulong va, ulong pa, ulong size)
+        {
+            while (size != 0)
+            {
+                _pageTable.Map(va, pa);
+
+                va += PageSize;
+                pa += PageSize;
+                size -= PageSize;
+            }
+        }
+
+        /// <inheritdoc/>
+        public void MapForeign(ulong va, nuint hostPointer, ulong size)
+        {
+            throw new NotSupportedException();
+        }
+
+        /// <inheritdoc/>
+        public void Unmap(ulong va, ulong size)
+        {
+            AssertValidAddressAndSize(va, size);
+
+            UnmapEvent?.Invoke(va, size);
+            Tracking.Unmap(va, size);
+
+            RemoveMapping(va, size);
+            _addressSpace.UnmapUser(va, size);
+            PtUnmap(va, size);
+        }
+
+        private void PtUnmap(ulong va, ulong size)
+        {
+            while (size != 0)
+            {
+                _pageTable.Unmap(va);
+
+                va += PageSize;
+                size -= PageSize;
+            }
+        }
+
+        /// <inheritdoc/>
+        public T Read<T>(ulong va) where T : unmanaged
+        {
+            return MemoryMarshal.Cast<byte, T>(GetSpan(va, Unsafe.SizeOf<T>()))[0];
+        }
+
+        /// <inheritdoc/>
+        public T ReadTracked<T>(ulong va) where T : unmanaged
+        {
+            try
+            {
+                SignalMemoryTracking(va, (ulong)Unsafe.SizeOf<T>(), false);
+
+                return Read<T>(va);
+            }
+            catch (InvalidMemoryRegionException)
+            {
+                if (_invalidAccessHandler == null || !_invalidAccessHandler(va))
+                {
+                    throw;
+                }
+
+                return default;
+            }
+        }
+
+        /// <inheritdoc/>
+        public void Read(ulong va, Span<byte> data)
+        {
+            ReadImpl(va, data);
+        }
+
+        /// <inheritdoc/>
+        public void Write<T>(ulong va, T value) where T : unmanaged
+        {
+            Write(va, MemoryMarshal.Cast<T, byte>(MemoryMarshal.CreateSpan(ref value, 1)));
+        }
+
+        /// <inheritdoc/>
+        public void Write(ulong va, ReadOnlySpan<byte> data)
+        {
+            if (data.Length == 0)
+            {
+                return;
+            }
+
+            SignalMemoryTracking(va, (ulong)data.Length, true);
+
+            WriteImpl(va, data);
+        }
+
+        /// <inheritdoc/>
+        public void WriteUntracked(ulong va, ReadOnlySpan<byte> data)
+        {
+            if (data.Length == 0)
+            {
+                return;
+            }
+
+            WriteImpl(va, data);
+        }
+
+        /// <inheritdoc/>
+        public bool WriteWithRedundancyCheck(ulong va, ReadOnlySpan<byte> data)
+        {
+            if (data.Length == 0)
+            {
+                return false;
+            }
+
+            SignalMemoryTracking(va, (ulong)data.Length, false);
+
+            if (IsContiguousAndMapped(va, data.Length))
+            {
+                var target = _backingMemory.GetSpan(GetPhysicalAddressInternal(va), data.Length);
+
+                bool changed = !data.SequenceEqual(target);
+
+                if (changed)
+                {
+                    data.CopyTo(target);
+                }
+
+                return changed;
+            }
+            else
+            {
+                WriteImpl(va, data);
+
+                return true;
+            }
+        }
+
+        private void WriteImpl(ulong va, ReadOnlySpan<byte> data)
+        {
+            try
+            {
+                AssertValidAddressAndSize(va, (ulong)data.Length);
+
+                if (IsContiguousAndMapped(va, data.Length))
+                {
+                    data.CopyTo(_backingMemory.GetSpan(GetPhysicalAddressInternal(va), data.Length));
+                }
+                else
+                {
+                    int offset = 0, size;
+
+                    if ((va & PageMask) != 0)
+                    {
+                        ulong pa = GetPhysicalAddressChecked(va);
+
+                        size = Math.Min(data.Length, PageSize - (int)(va & PageMask));
+
+                        data.Slice(0, size).CopyTo(_backingMemory.GetSpan(pa, size));
+
+                        offset += size;
+                    }
+
+                    for (; offset < data.Length; offset += size)
+                    {
+                        ulong pa = GetPhysicalAddressChecked(va + (ulong)offset);
+
+                        size = Math.Min(data.Length - offset, PageSize);
+
+                        data.Slice(offset, size).CopyTo(_backingMemory.GetSpan(pa, size));
+                    }
+                }
+            }
+            catch (InvalidMemoryRegionException)
+            {
+                if (_invalidAccessHandler == null || !_invalidAccessHandler(va))
+                {
+                    throw;
+                }
+            }
+        }
+
+        /// <inheritdoc/>
+        public ReadOnlySpan<byte> GetSpan(ulong va, int size, bool tracked = false)
+        {
+            if (size == 0)
+            {
+                return ReadOnlySpan<byte>.Empty;
+            }
+
+            if (tracked)
+            {
+                SignalMemoryTracking(va, (ulong)size, false);
+            }
+
+            if (IsContiguousAndMapped(va, size))
+            {
+                return _backingMemory.GetSpan(GetPhysicalAddressInternal(va), size);
+            }
+            else
+            {
+                Span<byte> data = new byte[size];
+
+                ReadImpl(va, data);
+
+                return data;
+            }
+        }
+
+        /// <inheritdoc/>
+        public WritableRegion GetWritableRegion(ulong va, int size, bool tracked = false)
+        {
+            if (size == 0)
+            {
+                return new WritableRegion(null, va, Memory<byte>.Empty);
+            }
+
+            if (tracked)
+            {
+                SignalMemoryTracking(va, (ulong)size, true);
+            }
+
+            if (IsContiguousAndMapped(va, size))
+            {
+                return new WritableRegion(null, va, _backingMemory.GetMemory(GetPhysicalAddressInternal(va), size));
+            }
+            else
+            {
+                Memory<byte> memory = new byte[size];
+
+                ReadImpl(va, memory.Span);
+
+                return new WritableRegion(this, va, memory);
+            }
+        }
+
+        /// <inheritdoc/>
+        public ref T GetRef<T>(ulong va) where T : unmanaged
+        {
+            if (!IsContiguous(va, Unsafe.SizeOf<T>()))
+            {
+                ThrowMemoryNotContiguous();
+            }
+
+            SignalMemoryTracking(va, (ulong)Unsafe.SizeOf<T>(), true);
+
+            return ref _backingMemory.GetRef<T>(GetPhysicalAddressChecked(va));
+        }
+
+        /// <inheritdoc/>
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        public bool IsMapped(ulong va)
+        {
+            return ValidateAddress(va) && IsMappedImpl(va);
+        }
+
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        private bool IsMappedImpl(ulong va)
+        {
+            ulong page = va >> PageBits;
+
+            int bit = (int)((page & 31) << 1);
+
+            int pageIndex = (int)(page >> PageToPteShift);
+            ref ulong pageRef = ref _pageBitmap[pageIndex];
+
+            ulong pte = Volatile.Read(ref pageRef);
+
+            return ((pte >> bit) & 3) != 0;
+        }
+
+        /// <inheritdoc/>
+        public bool IsRangeMapped(ulong va, ulong size)
+        {
+            AssertValidAddressAndSize(va, size);
+
+            return IsRangeMappedImpl(va, size);
+        }
+
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        private void GetPageBlockRange(ulong pageStart, ulong pageEnd, out ulong startMask, out ulong endMask, out int pageIndex, out int pageEndIndex)
+        {
+            startMask = ulong.MaxValue << ((int)(pageStart & 31) << 1);
+            endMask = ulong.MaxValue >> (64 - ((int)(pageEnd & 31) << 1));
+
+            pageIndex = (int)(pageStart >> PageToPteShift);
+            pageEndIndex = (int)((pageEnd - 1) >> PageToPteShift);
+        }
+
+        private bool IsRangeMappedImpl(ulong va, ulong size)
+        {
+            int pages = GetPagesCount(va, size, out _);
+
+            if (pages == 1)
+            {
+                return IsMappedImpl(va);
+            }
+
+            ulong pageStart = va >> PageBits;
+            ulong pageEnd = pageStart + (ulong)pages;
+
+            GetPageBlockRange(pageStart, pageEnd, out ulong startMask, out ulong endMask, out int pageIndex, out int pageEndIndex);
+
+            // Check if either bit in each 2 bit page entry is set.
+            // OR the block with itself shifted down by 1, and check the first bit of each entry.
+
+            ulong mask = BlockMappedMask & startMask;
+
+            while (pageIndex <= pageEndIndex)
+            {
+                if (pageIndex == pageEndIndex)
+                {
+                    mask &= endMask;
+                }
+
+                ref ulong pageRef = ref _pageBitmap[pageIndex++];
+                ulong pte = Volatile.Read(ref pageRef);
+
+                pte |= pte >> 1;
+                if ((pte & mask) != mask)
+                {
+                    return false;
+                }
+
+                mask = BlockMappedMask;
+            }
+
+            return true;
+        }
+
+        private static void ThrowMemoryNotContiguous() => throw new MemoryNotContiguousException();
+
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        private bool IsContiguousAndMapped(ulong va, int size) => IsContiguous(va, size) && IsMapped(va);
+
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        private bool IsContiguous(ulong va, int size)
+        {
+            if (!ValidateAddress(va) || !ValidateAddressAndSize(va, (ulong)size))
+            {
+                return false;
+            }
+
+            int pages = GetPagesCount(va, (uint)size, out va);
+
+            for (int page = 0; page < pages - 1; page++)
+            {
+                if (!ValidateAddress(va + PageSize))
+                {
+                    return false;
+                }
+
+                if (GetPhysicalAddressInternal(va) + PageSize != GetPhysicalAddressInternal(va + PageSize))
+                {
+                    return false;
+                }
+
+                va += PageSize;
+            }
+
+            return true;
+        }
+
+        /// <inheritdoc/>
+        public IEnumerable<HostMemoryRange> GetHostRegions(ulong va, ulong size)
+        {
+            if (size == 0)
+            {
+                return Enumerable.Empty<HostMemoryRange>();
+            }
+
+            var guestRegions = GetPhysicalRegionsImpl(va, size);
+            if (guestRegions == null)
+            {
+                return null;
+            }
+
+            var regions = new HostMemoryRange[guestRegions.Count];
+
+            for (int i = 0; i < regions.Length; i++)
+            {
+                var guestRegion = guestRegions[i];
+                IntPtr pointer = _backingMemory.GetPointer(guestRegion.Address, guestRegion.Size);
+                regions[i] = new HostMemoryRange((nuint)(ulong)pointer, guestRegion.Size);
+            }
+
+            return regions;
+        }
+
+        /// <inheritdoc/>
+        public IEnumerable<MemoryRange> GetPhysicalRegions(ulong va, ulong size)
+        {
+            if (size == 0)
+            {
+                return Enumerable.Empty<MemoryRange>();
+            }
+
+            return GetPhysicalRegionsImpl(va, size);
+        }
+
+        private List<MemoryRange> GetPhysicalRegionsImpl(ulong va, ulong size)
+        {
+            if (!ValidateAddress(va) || !ValidateAddressAndSize(va, size))
+            {
+                return null;
+            }
+
+            int pages = GetPagesCount(va, (uint)size, out va);
+
+            var regions = new List<MemoryRange>();
+
+            ulong regionStart = GetPhysicalAddressInternal(va);
+            ulong regionSize = PageSize;
+
+            for (int page = 0; page < pages - 1; page++)
+            {
+                if (!ValidateAddress(va + PageSize))
+                {
+                    return null;
+                }
+
+                ulong newPa = GetPhysicalAddressInternal(va + PageSize);
+
+                if (GetPhysicalAddressInternal(va) + PageSize != newPa)
+                {
+                    regions.Add(new MemoryRange(regionStart, regionSize));
+                    regionStart = newPa;
+                    regionSize = 0;
+                }
+
+                va += PageSize;
+                regionSize += PageSize;
+            }
+
+            regions.Add(new MemoryRange(regionStart, regionSize));
+
+            return regions;
+        }
+
+        private void ReadImpl(ulong va, Span<byte> data)
+        {
+            if (data.Length == 0)
+            {
+                return;
+            }
+
+            try
+            {
+                AssertValidAddressAndSize(va, (ulong)data.Length);
+
+                int offset = 0, size;
+
+                if ((va & PageMask) != 0)
+                {
+                    ulong pa = GetPhysicalAddressChecked(va);
+
+                    size = Math.Min(data.Length, PageSize - (int)(va & PageMask));
+
+                    _backingMemory.GetSpan(pa, size).CopyTo(data.Slice(0, size));
+
+                    offset += size;
+                }
+
+                for (; offset < data.Length; offset += size)
+                {
+                    ulong pa = GetPhysicalAddressChecked(va + (ulong)offset);
+
+                    size = Math.Min(data.Length - offset, PageSize);
+
+                    _backingMemory.GetSpan(pa, size).CopyTo(data.Slice(offset, size));
+                }
+            }
+            catch (InvalidMemoryRegionException)
+            {
+                if (_invalidAccessHandler == null || !_invalidAccessHandler(va))
+                {
+                    throw;
+                }
+            }
+        }
+
+        /// <inheritdoc/>
+        /// <remarks>
+        /// This function also validates that the given range is both valid and mapped, and will throw if it is not.
+        /// </remarks>
+        public void SignalMemoryTracking(ulong va, ulong size, bool write, bool precise = false)
+        {
+            AssertValidAddressAndSize(va, size);
+
+            if (precise)
+            {
+                Tracking.VirtualMemoryEvent(va, size, write, precise: true);
+                return;
+            }
+
+            // Software table, used for managed memory tracking.
+
+            int pages = GetPagesCount(va, size, out _);
+            ulong pageStart = va >> PageBits;
+
+            if (pages == 1)
+            {
+                ulong tag = (ulong)(write ? HostMappedPtBits.WriteTracked : HostMappedPtBits.ReadWriteTracked);
+
+                int bit = (int)((pageStart & 31) << 1);
+
+                int pageIndex = (int)(pageStart >> PageToPteShift);
+                ref ulong pageRef = ref _pageBitmap[pageIndex];
+
+                ulong pte = Volatile.Read(ref pageRef);
+                ulong state = ((pte >> bit) & 3);
+
+                if (state >= tag)
+                {
+                    Tracking.VirtualMemoryEvent(va, size, write);
+                    return;
+                }
+                else if (state == 0)
+                {
+                    ThrowInvalidMemoryRegionException($"Not mapped: va=0x{va:X16}, size=0x{size:X16}");
+                }
+            }
+            else
+            {
+                ulong pageEnd = pageStart + (ulong)pages;
+
+                GetPageBlockRange(pageStart, pageEnd, out ulong startMask, out ulong endMask, out int pageIndex, out int pageEndIndex);
+
+                ulong mask = startMask;
+
+                ulong anyTrackingTag = (ulong)HostMappedPtBits.WriteTrackedReplicated;
+
+                while (pageIndex <= pageEndIndex)
+                {
+                    if (pageIndex == pageEndIndex)
+                    {
+                        mask &= endMask;
+                    }
+
+                    ref ulong pageRef = ref _pageBitmap[pageIndex++];
+
+                    ulong pte = Volatile.Read(ref pageRef);
+                    ulong mappedMask = mask & BlockMappedMask;
+
+                    ulong mappedPte = pte | (pte >> 1);
+                    if ((mappedPte & mappedMask) != mappedMask)
+                    {
+                        ThrowInvalidMemoryRegionException($"Not mapped: va=0x{va:X16}, size=0x{size:X16}");
+                    }
+
+                    pte &= mask;
+                    if ((pte & anyTrackingTag) != 0) // Search for any tracking.
+                    {
+                        // Writes trigger any tracking.
+                        // Only trigger tracking from reads if both bits are set on any page.
+                        if (write || (pte & (pte >> 1) & BlockMappedMask) != 0)
+                        {
+                            Tracking.VirtualMemoryEvent(va, size, write);
+                            break;
+                        }
+                    }
+
+                    mask = ulong.MaxValue;
+                }
+            }
+        }
+
+        /// <summary>
+        /// Computes the number of pages in a virtual address range.
+        /// </summary>
+        /// <param name="va">Virtual address of the range</param>
+        /// <param name="size">Size of the range</param>
+        /// <param name="startVa">The virtual address of the beginning of the first page</param>
+        /// <remarks>This function does not differentiate between allocated and unallocated pages.</remarks>
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        private int GetPagesCount(ulong va, ulong size, out ulong startVa)
+        {
+            // WARNING: Always check if ulong does not overflow during the operations.
+            startVa = va & ~(ulong)PageMask;
+            ulong vaSpan = (va - startVa + size + PageMask) & ~(ulong)PageMask;
+
+            return (int)(vaSpan / PageSize);
+        }
+
+        /// <inheritdoc/>
+        public void TrackingReprotect(ulong va, ulong size, MemoryPermission protection)
+        {
+            // Protection is inverted on software pages, since the default value is 0.
+            protection = (~protection) & MemoryPermission.ReadAndWrite;
+
+            int pages = GetPagesCount(va, size, out va);
+            ulong pageStart = va >> PageBits;
+
+            if (pages == 1)
+            {
+                ulong protTag = protection switch
+                {
+                    MemoryPermission.None => (ulong)HostMappedPtBits.Mapped,
+                    MemoryPermission.Write => (ulong)HostMappedPtBits.WriteTracked,
+                    _ => (ulong)HostMappedPtBits.ReadWriteTracked,
+                };
+
+                int bit = (int)((pageStart & 31) << 1);
+
+                ulong tagMask = 3UL << bit;
+                ulong invTagMask = ~tagMask;
+
+                ulong tag = protTag << bit;
+
+                int pageIndex = (int)(pageStart >> PageToPteShift);
+                ref ulong pageRef = ref _pageBitmap[pageIndex];
+
+                ulong pte;
+
+                do
+                {
+                    pte = Volatile.Read(ref pageRef);
+                }
+                while ((pte & tagMask) != 0 && Interlocked.CompareExchange(ref pageRef, (pte & invTagMask) | tag, pte) != pte);
+            }
+            else
+            {
+                ulong pageEnd = pageStart + (ulong)pages;
+
+                GetPageBlockRange(pageStart, pageEnd, out ulong startMask, out ulong endMask, out int pageIndex, out int pageEndIndex);
+
+                ulong mask = startMask;
+
+                ulong protTag = protection switch
+                {
+                    MemoryPermission.None => (ulong)HostMappedPtBits.MappedReplicated,
+                    MemoryPermission.Write => (ulong)HostMappedPtBits.WriteTrackedReplicated,
+                    _ => (ulong)HostMappedPtBits.ReadWriteTrackedReplicated,
+                };
+
+                while (pageIndex <= pageEndIndex)
+                {
+                    if (pageIndex == pageEndIndex)
+                    {
+                        mask &= endMask;
+                    }
+
+                    ref ulong pageRef = ref _pageBitmap[pageIndex++];
+
+                    ulong pte;
+                    ulong mappedMask;
+
+                    // Change the protection of all 2 bit entries that are mapped.
+                    do
+                    {
+                        pte = Volatile.Read(ref pageRef);
+
+                        mappedMask = pte | (pte >> 1);
+                        mappedMask |= (mappedMask & BlockMappedMask) << 1;
+                        mappedMask &= mask; // Only update mapped pages within the given range.
+                    }
+                    while (Interlocked.CompareExchange(ref pageRef, (pte & (~mappedMask)) | (protTag & mappedMask), pte) != pte);
+
+                    mask = ulong.MaxValue;
+                }
+            }
+
+            protection = protection switch
+            {
+                MemoryPermission.None => MemoryPermission.ReadAndWrite,
+                MemoryPermission.Write => MemoryPermission.Read,
+                _ => MemoryPermission.None
+            };
+
+            _addressSpace.ReprotectUser(va, size, protection);
+        }
+
+        /// <inheritdoc/>
+        public CpuRegionHandle BeginTracking(ulong address, ulong size)
+        {
+            return new CpuRegionHandle(Tracking.BeginTracking(address, size));
+        }
+
+        /// <inheritdoc/>
+        public CpuMultiRegionHandle BeginGranularTracking(ulong address, ulong size, IEnumerable<IRegionHandle> handles, ulong granularity)
+        {
+            return new CpuMultiRegionHandle(Tracking.BeginGranularTracking(address, size, handles, granularity));
+        }
+
+        /// <inheritdoc/>
+        public CpuSmartMultiRegionHandle BeginSmartGranularTracking(ulong address, ulong size, ulong granularity)
+        {
+            return new CpuSmartMultiRegionHandle(Tracking.BeginSmartGranularTracking(address, size, granularity));
+        }
+
+        /// <summary>
+        /// Adds the given address mapping to the page table.
+        /// </summary>
+        /// <param name="va">Virtual memory address</param>
+        /// <param name="size">Size to be mapped</param>
+        private void AddMapping(ulong va, ulong size)
+        {
+            int pages = GetPagesCount(va, size, out _);
+            ulong pageStart = va >> PageBits;
+            ulong pageEnd = pageStart + (ulong)pages;
+
+            GetPageBlockRange(pageStart, pageEnd, out ulong startMask, out ulong endMask, out int pageIndex, out int pageEndIndex);
+
+            ulong mask = startMask;
+
+            while (pageIndex <= pageEndIndex)
+            {
+                if (pageIndex == pageEndIndex)
+                {
+                    mask &= endMask;
+                }
+
+                ref ulong pageRef = ref _pageBitmap[pageIndex++];
+
+                ulong pte;
+                ulong mappedMask;
+
+                // Map all 2-bit entries that are unmapped.
+                do
+                {
+                    pte = Volatile.Read(ref pageRef);
+
+                    mappedMask = pte | (pte >> 1);
+                    mappedMask |= (mappedMask & BlockMappedMask) << 1;
+                    mappedMask |= ~mask; // Treat everything outside the range as mapped, thus unchanged.
+                }
+                while (Interlocked.CompareExchange(ref pageRef, (pte & mappedMask) | (BlockMappedMask & (~mappedMask)), pte) != pte);
+
+                mask = ulong.MaxValue;
+            }
+        }
+
+        /// <summary>
+        /// Removes the given address mapping from the page table.
+        /// </summary>
+        /// <param name="va">Virtual memory address</param>
+        /// <param name="size">Size to be unmapped</param>
+        private void RemoveMapping(ulong va, ulong size)
+        {
+            int pages = GetPagesCount(va, size, out _);
+            ulong pageStart = va >> PageBits;
+            ulong pageEnd = pageStart + (ulong)pages;
+
+            GetPageBlockRange(pageStart, pageEnd, out ulong startMask, out ulong endMask, out int pageIndex, out int pageEndIndex);
+
+            startMask = ~startMask;
+            endMask = ~endMask;
+
+            ulong mask = startMask;
+
+            while (pageIndex <= pageEndIndex)
+            {
+                if (pageIndex == pageEndIndex)
+                {
+                    mask |= endMask;
+                }
+
+                ref ulong pageRef = ref _pageBitmap[pageIndex++];
+                ulong pte;
+
+                do
+                {
+                    pte = Volatile.Read(ref pageRef);
+                }
+                while (Interlocked.CompareExchange(ref pageRef, pte & mask, pte) != pte);
+
+                mask = 0;
+            }
+        }
+
+        private ulong GetPhysicalAddressChecked(ulong va)
+        {
+            if (!IsMapped(va))
+            {
+                ThrowInvalidMemoryRegionException($"Not mapped: va=0x{va:X16}");
+            }
+
+            return GetPhysicalAddressInternal(va);
+        }
+
+        private ulong GetPhysicalAddressInternal(ulong va)
+        {
+            return _pageTable.Read(va) + (va & PageMask);
+        }
+
+        /// <summary>
+        /// Disposes of resources used by the memory manager.
+        /// </summary>
+        protected override void Destroy()
+        {
+            _addressSpace.Dispose();
+        }
+
+        private static void ThrowInvalidMemoryRegionException(string message) => throw new InvalidMemoryRegionException(message);
+    }
+}
+\ No newline at end of file