Kernel: Remove kmalloc identity map requirement from USB keyboard

This is the last place requiring kmalloc identity mapping

kernel/include/kernel/USB/HID/Keyboard.h

@@ -11,6 +11,8 @@ namespace Kernel
 		BAN_NON_MOVABLE(USBKeyboard);
 
 	public:
+		BAN::ErrorOr<void> initialize() override;
+
 		void start_report() override;
 		void stop_report() override;
 
@@ -38,6 +40,8 @@ namespace Kernel
 		uint16_t m_toggle_mask { 0 };
 
 		uint16_t m_led_mask { 0 };
+		BAN::UniqPtr<DMARegion> m_led_region;
+
 		BAN::Vector<USBHID::Report> m_outputs;
 
 		BAN::Optional<uint8_t> m_repeat_scancode;

kernel/kernel/USB/HID/Keyboard.cpp

@@ -22,6 +22,12 @@ namespace Kernel
 		set_leds(0);
 	}
 
+	BAN::ErrorOr<void> USBKeyboard::initialize()
+	{
+		m_led_region = TRY(DMARegion::create(PAGE_SIZE, PageTable::MemoryType::Normal));
+		return {};
+	}
+
 	void USBKeyboard::start_report()
 	{
 		m_lock_state = m_keyboard_lock.lock();
@@ -190,6 +196,9 @@ namespace Kernel
 	{
 		using KeyModifier = LibInput::KeyEvent::Modifier;
 
+		if (!m_led_region)
+			return;
+
 		size_t report_bits = 0;
 		for (const auto& report : m_outputs)
 		{
@@ -199,10 +208,11 @@ namespace Kernel
 		}
 
 		const size_t report_bytes = (report_bits + 7) / 8;
+		ASSERT(report_bytes <= PAGE_SIZE);
+
+		PageTable::with_fast_page(m_led_region->paddr(), [&] {
+			uint8_t* data = &PageTable::fast_page_as<uint8_t>();
 
-		uint8_t* data = static_cast<uint8_t*>(kmalloc(report_bytes));
-		if (data == nullptr)
-			return;
 			memset(data, 0, report_bytes);
 
 			size_t bit_offset = 0;
@@ -233,6 +243,7 @@ namespace Kernel
 
 				bit_offset += report.report_size * report.report_count;
 			}
+		});
 
 		USBDeviceRequest request;
 		request.bmRequestType = USB::RequestType::HostToDevice | USB::RequestType::Class | USB::RequestType::Interface;
@@ -240,10 +251,8 @@ namespace Kernel
 		request.wValue = 0x0200 | report_id;
 		request.wIndex = m_driver.interface().descriptor.bInterfaceNumber;
 		request.wLength = report_bytes;
-		if (auto ret = m_driver.device().send_request(request, kmalloc_paddr_of(reinterpret_cast<vaddr_t>(data)).value()); ret.is_error())
+		if (auto ret = m_driver.device().send_request(request, m_led_region->paddr()); ret.is_error())
 			dprintln_if(DEBUG_USB_KEYBOARD, "Failed to update LEDs: {}", ret.error());
-
-		kfree(data);
 	}
 
 	void initialize_scancode_to_keycode()