feat(arm64): higher-half kernel, early MMU in boot, and VMM

Kernel/Include/VM/PMM.h

@@ -1,5 +1,6 @@
 #pragma once
 #include <Types.h>
+#include "../Common/bootinfo.h"
 
 enum {
     kVMPageSize = 4096,
@@ -12,12 +13,14 @@ typedef struct {
     Size size;
 } VMMemoryRegion;
 
+
 typedef struct {
     VMMemoryRegion totalRAM;
     VMMemoryRegion reserved[kVMMaxReservedRegions];
     UInt32 reservedCount;
+    VMMemoryRegion UART;
 } VMBootMemoryMap;
 
-void PMMInitialize(VMBootMemoryMap* bootMap);
+void PMMInitialize(VMBootMemoryMap* bootMap, Bootinfo* info);
 Pointer PMMAllocatePage();
 void PMMFreePage(Address address);

Kernel/Include/VM/VMM.h

@@ -0,0 +1,49 @@
+#pragma once
+#include <Types.h>
+#include <VM/PMM.h>
+#include "../Common/bootinfo.h"
+
+enum VMPTEFlags {
+    kPTEValid      = (1ULL << 0),  // 1 = Present (Will page fault if 0)
+    kPTETable      = (1ULL << 1),  // 1 = Valid for L0/L1/L2 Directory
+    kPTEPage       = (1ULL << 1),  // 1 = Valid for L3 Page (Same bit)
+
+    kPTENormalMem  = (0ULL << 2),  // Cached, Normal RAM
+    kPTEDeviceMem  = (1ULL << 2),  // Uncached, MMIO Device
+
+    kPTEAccessRW   = (0ULL << 6),  // Read/Write
+    kPTEAccessRO   = (1ULL << 6),  // Read-Only
+    kPTEUser       = (1ULL << 7),  // 1 = EL0, 0 = EL1
+
+    kPTEInnerShare = (3ULL << 8),  // Inner Shareable (SMP safe)
+    kPTEAccessFlag = (1ULL << 10), // CPU access tracking (MUST be 1 to avoid faults)
+    kPTEPrivNX     = (1ULL << 53), // PXN: Privileged Execute Never
+    kPTEUserNX     = (1ULL << 54)  // UXN: Unprivileged Execute Never
+};
+
+enum {
+    kVMKernelVMA   = 0xFFFFFFFF80000000,
+    kHHDMOffset    = 0xFFFF888000000000,
+    kVMFbVirtBase  = 0xFFFFFFFFFC000000,
+};
+
+
+static inline Address VMKernelVirtToPhys(Address virt) {
+    return virt - kVMKernelVMA;
+}
+
+static inline Address VMPhysToHHDM(Address phys) {
+    return phys + kHHDMOffset;
+}
+
+static inline Address VMHHDMToPhys(Address virt) {
+    return virt - kHHDMOffset;
+}
+
+extern Address* gVMKernelL0Table;
+extern Address gVMKernelL0Physical;
+
+Address* VMMMapPage(Address* l0Table, Address phys, Address virt, UInt64 flags);
+void VMMUnmapPage(Address* l0Table, Address virt);
+Pointer VMMGetOrAllocatePage(Address* l0Table, Address virt, UInt64 flags);
+void VMMInitialize(VMBootMemoryMap* bootMap, Bootinfo* info);