graphics: upload sparse PRT image backing

src/graphics/host_gpu/renderer/cache/bufferCache.cpp

@@ -621,7 +621,8 @@ ImageBufferSource BufferCache::ObtainBufferForImage(uint64_t vaddr, uint64_t siz
 	}
 
 	auto [staging, stage_offset] = m_staging_buffer.Map(size, 16);
-	if (staging == nullptr || !Libs::LibKernel::Memory::TryReadBacking(vaddr, staging, size)) {
+	if (staging == nullptr || (!Libs::LibKernel::Memory::TryReadBacking(vaddr, staging, size) &&
+	                           !Libs::LibKernel::Memory::TryReadPrtBacking(vaddr, staging, size))) {
 		EXIT("BufferCache: failed to read mapped guest image backing\n");
 	}
 	m_staging_buffer.Commit();

src/kernel/memory.cpp

@@ -921,18 +921,39 @@ constexpr uint64_t PRT_APERTURE_END       = 0xfc00000000ull;
 static std::array<PrtAperture, PRT_APERTURE_MAX_INDEX + 1> g_prt_apertures {};
 static Common::Mutex                                       g_prt_aperture_mutex;
 
-static bool IsInPrtAperture(uint64_t address) {
+static bool IsInPrtAperture(uint64_t address, uint64_t size = 1) {
+	if (size == 0 || UINT64_MAX - address < size) {
+		return false;
+	}
 	Common::LockGuard lock(g_prt_aperture_mutex);
 
 	for (const auto& aperture: g_prt_apertures) {
-		if (address >= aperture.address && address < aperture.address + aperture.size) {
-			return true;
+		if (address >= aperture.address) {
+			const auto offset = address - aperture.address;
+			if (offset < aperture.size && size <= aperture.size - offset) {
+				return true;
+			}
 		}
 	}
 
 	return false;
 }
 
+bool TryReadPrtBacking(uint64_t vaddr, void* data, uint64_t size) {
+	std::vector<VirtualRanges::Range> ranges;
+	if (g_guest_address_space == nullptr || g_virtual_ranges == nullptr ||
+	    !IsInPrtAperture(vaddr, size) || !g_virtual_ranges->QuerySpan(vaddr, size, &ranges)) {
+		return false;
+	}
+	if (std::any_of(ranges.begin(), ranges.end(), [](const auto& range) {
+		    return !IsReservedRangeType(range.type) &&
+		           !g_guest_address_space->BackingContains(range.start, range.size);
+	    })) {
+		return false;
+	}
+	return g_guest_address_space->TryReadSparseBacking(vaddr, data, size);
+}
+
 static bool SelfTestSub64SharedPlaceholderAlias() {
 #if KYTY_PLATFORM == KYTY_PLATFORM_WINDOWS
 	constexpr uint64_t PageSize    = 0x4000;

src/kernel/memory.h

@@ -109,6 +109,7 @@ void                   RegisterCallbacks(callback_func_t alloc_func, callback_fu
 void                   SetFlexibleMemorySize(uint64_t size);
 bool                   TryWriteBacking(uint64_t vaddr, const void* data, uint64_t size);
 bool                   TryReadBacking(uint64_t vaddr, void* data, uint64_t size);
+bool                   TryReadPrtBacking(uint64_t vaddr, void* data, uint64_t size);
 [[nodiscard]] uint64_t ClampRangeSize(uint64_t vaddr, uint64_t size);
 void                   WriteBacking(uint64_t vaddr, const void* data, uint64_t size) noexcept;
 void                   InvalidateMemory(uint64_t vaddr, uint64_t size);

src/kernel/memoryAddressSpace.inc

@@ -188,6 +188,43 @@ public:
 		    });
 	}
 
+	bool TryReadSparseBacking(uint64_t vaddr, void* data, uint64_t size) {
+		if (!IsAvailable() || data == nullptr || size == 0 || UINT64_MAX - vaddr < size) {
+			return false;
+		}
+
+		std::lock_guard lock(m_mutex);
+		const auto      end   = vaddr + size;
+		auto            first = m_maps.lower_bound(vaddr);
+		if (first != m_maps.begin()) {
+			auto previous = std::prev(first);
+			if (previous->second.vaddr + previous->second.size > vaddr) {
+				first = previous;
+			}
+		}
+		for (auto mapping = first; mapping != m_maps.end() && mapping->second.vaddr < end;
+		     ++mapping) {
+			const auto& entry = mapping->second;
+			const auto  start = std::max(vaddr, entry.vaddr);
+			const auto  bytes = std::min(end, entry.vaddr + entry.size) - start;
+			if (!RangeOk(entry.backing_offset + start - entry.vaddr, bytes)) {
+				return false;
+			}
+		}
+
+		auto* destination = static_cast<uint8_t*>(data);
+		std::memset(destination, 0, size);
+		for (auto mapping = first; mapping != m_maps.end() && mapping->second.vaddr < end;
+		     ++mapping) {
+			const auto& entry  = mapping->second;
+			const auto  start  = std::max(vaddr, entry.vaddr);
+			const auto  bytes  = std::min(end, entry.vaddr + entry.size) - start;
+			const auto  offset = entry.backing_offset + start - entry.vaddr;
+			std::memcpy(destination + start - vaddr, m_backing_base + offset, bytes);
+		}
+		return true;
+	}
+
 	bool MapExistingPlaceholderFixed(uint64_t vaddr, uint64_t size, uint64_t backing_offset,
 	                                 VirtualMemory::Mode mode,
 	                                 FailureReason*      failure_reason = nullptr) {
@@ -694,6 +731,10 @@ public:
 		return m_backing->TryReadBacking(vaddr, data, size);
 	}
 
+	bool TryReadSparseBacking(uint64_t vaddr, void* data, uint64_t size) {
+		return m_backing->TryReadSparseBacking(vaddr, data, size);
+	}
+
 	bool BackingContains(uint64_t vaddr, uint64_t size) { return m_backing->Contains(vaddr, size); }
 
 	bool Protect(uint64_t vaddr, uint64_t size, VirtualMemory::Mode mode) {