1 files changed, 143 insertions, 0 deletions
diff --git a/src/common/sparse_large_vector.cpp b/src/common/sparse_large_vector.cpp
new file mode 100644
index 0000000000..ce6455a235
--- /dev/null
+++ b/src/common/sparse_large_vector.cpp
@@ -0,0 +1,143 @@
+// SPDX-FileCopyrightText: Copyright 2026 Eden Emulator Project
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+/* virtual_buffer.cpp */
+// SPDX-FileCopyrightText: Copyright 2020 yuzu Emulator Project
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+#ifdef _WIN32
+#include <windows.h>
+#include <mutex>
+#else
+#include <sys/mman.h>
+#endif
+
+#include "common/alignment.h"
+#include "common/assert.h"
+#include "common/sparse_large_vector.h"
+
+namespace Common {
+
+#ifdef _WIN32
+static std::vector<std::pair<u64, u64>> vector_regions {};
+
+// Workaround for handling non-commited memory accessed by Dynarmic; usually result of an error
+static LONG WINAPI FakePageFaultHandler(PEXCEPTION_POINTERS info) {
+    DWORD code = info->ExceptionRecord->ExceptionCode;
+    u64 exception_addr = reinterpret_cast<u64>(info->ExceptionRecord->ExceptionAddress);
+
+    if (code != EXCEPTION_ACCESS_VIOLATION) {
+        // Not our problem
+        return EXCEPTION_CONTINUE_SEARCH;
+    }
+
+    u64 addr = 0, addr2 = 0;
+
+    for (auto region: vector_regions) {
+        auto addr_shifted = exception_addr >> HostPageBits;
+        if (region.first <= addr_shifted && addr_shifted <= region.second) {
+            addr = addr_shifted;
+        }
+
+        // Page-boundary accesses
+        if (auto addr_ = (exception_addr + 0x40) >> HostPageBits; addr_ != addr_shifted && region.first <= addr_ && addr_ <= region.second) {
+            addr2 = addr_;
+        }
+
+        if (addr != 0 || addr2 != 0) {
+            break;
+        }
+    }
+
+    if (addr == 0 && addr2 == 0) {
+        // Not our problem
+        return EXCEPTION_CONTINUE_SEARCH;
+    }
+
+    LOG_ERROR(HW_Memory, "Accessing an unallocated region of a SparseLargeVector at {:#x}; this shouldn't happen and is likely a Dynarmic error!", exception_addr);
+
+    // Commit this region
+    if (addr != 0) {
+        if (!CommitVectorPage(addr << HostPageBits, false)) {
+            return EXCEPTION_CONTINUE_SEARCH;
+        }
+    }
+    // Commit next region if needed
+    if (addr2 != 0) {
+        if (!CommitVectorPage(addr2 << HostPageBits, false)) {
+            return EXCEPTION_CONTINUE_SEARCH;
+        }
+    }
+
+    return EXCEPTION_CONTINUE_EXECUTION;
+}
+
+bool CommitVectorPage(uintptr_t addr, bool write) noexcept {
+    MEMORY_BASIC_INFORMATION info {};
+    auto res = VirtualQuery(reinterpret_cast<void*>(addr), &info, sizeof(info));
+    if (res == 0) {
+        LOG_CRITICAL(HW_Memory, "Failed to query large buffer region at {:#x} with error {}, will try committing anyway", addr, GetLastError());
+    } else if (info.State != MEM_RESERVE) {
+        LOG_ERROR(HW_Memory, "Tried to commit an unreserved large buffer region at {:#x} that is not mapped or is already committed (state {:#x})", addr, info.State);
+        return false;
+    }
+
+    auto perm = write ? PAGE_READWRITE : PAGE_READONLY;
+    void* res2 = VirtualAlloc(reinterpret_cast<LPVOID>(addr), HostPageSize, MEM_COMMIT, perm);
+    if (res2 == nullptr) {
+        LOG_ERROR(HW_Memory, "Failed to commit large buffer region at {:#x}, error {}", addr, GetLastError());
+        return false;
+    }
+
+    return true;
+}
+#endif
+
+#ifndef MAP_NOCORE
+#define MAP_NOCORE 0
+#endif
+
+void* AllocateMemoryPages(std::size_t size) noexcept {
+    if (auto page = HostPageSize; size % page != 0) {
+        LOG_WARNING(HW_Memory, "Allocating unaligned large vector with size {:#x}; aligning to {} page size", size, page);
+        size = AlignUp(size, page);
+    }
+
+#ifdef _WIN32
+    // We will never use this memory entirely so instead of committing it up front let's just reserve it and commit each page individually
+    void* base = VirtualAlloc(nullptr, size, MEM_RESERVE, PAGE_READWRITE);
+
+    if (base != nullptr) {
+        vector_regions.emplace_back(reinterpret_cast<u64>(base), reinterpret_cast<u64>(base) + size);
+
+        static std::once_flag flag;
+        std::call_once(flag, []() { AddVectoredExceptionHandler(1, FakePageFaultHandler); });
+    } else {
+        // Try committing everything instead??
+        LOG_WARNING(HW_Memory, "Failed to reserve large vector region with error {}, trying to commit instead..", GetLastError());
+        base = VirtualAlloc(nullptr, size, MEM_COMMIT, PAGE_READWRITE);
+    }
+    ASSERT_MSG(base, "Failed to reserve {:#x} sized region with error {}", size, GetLastError());
+#else
+    void* base = mmap(nullptr, size, PROT_READ, MAP_ANON | MAP_PRIVATE | MAP_NOCORE, -1, 0);
+    if (base == MAP_FAILED)
+        base = nullptr;
+    ASSERT_MSG(base, "Failed to allocate {:#x} sized region with error {}", size, strerror(errno));
+#endif
+    return base;
+}
+
+void FreeMemoryPages(void* base, [[maybe_unused]] std::size_t size) noexcept {
+    if (auto page = HostPageSize; size % page != 0) {
+        size = AlignUp(size, page);
+    }
+    if (!base)
+        return;
+#ifdef _WIN32
+    ASSERT(VirtualFree(base, 0, MEM_RELEASE));
+#else
+    ASSERT(munmap(base, size) == 0);
+#endif
+}
+
+} // namespace Common