Kernel: Make i8042 controller initialization sequence more robust

The setting of scan code set sequence is removed, as it's buggy and
could lead the controller to fail immediately when doing self-test
afterwards. We will restore it when we understand how to do so safely.

Allow the user to determine a preferred detection path with a new kernel
command line argument. The defualt option is to check i8042 presence
with an ACPI check and if necessary - an "aggressive" test to determine
i8042 existence in the system.
Also, keep the i8042 controller pointer on the stack, so don't assign
m_i8042_controller member pointer if it does not exist.

Base/usr/share/man/man7/boot_parameters.md

@@ -29,8 +29,6 @@ List of options:
 
 * **`disable_physical_storage`** - If present on the command line, neither AHCI, or IDE controllers will be initialized on boot.
     
-* **`disable_ps2_controller`** - If present on the command line, the I8042 keyboard controller will not be initialized on boot.
-  
 * **`disable_uhci_controller`** - If present on the command line, the UHCI controller will not be initialized on boot.
 
 * **`disable_virtio`** - If present on the command line, virtio devices will not be detected, and initialized on boot.
@@ -61,6 +59,12 @@ has set up before booting the Kernel, don't initialize any driver.
 * **`init_args`** - This parameter expects a set of arguments to pass to the **`init`** program.
   The value should be a set of strings separated by `,` characters.
 
+* **`i8042_presence_mode`** - This parameter expects one of the following values:
+  **`aggressive-test`** - The i8042 initialization sequence should only try an aggressive presence test.
+  **`auto`** - The i8042 initialization sequence should try to check if ACPI says i8042 exists, and if not an aggressive presence test should take place to determine presence. 
+  **`none`** - Assume there's no i8042 controller in the system. 
+  **`force`** - Assume there's i8042 controller in the system.
+
 * **`panic`** - This parameter expects **`halt`** or **`shutdown`**. This is particularly useful in CI contexts.
 
 * **`pci`** - This parameter expects **`ecam`**, **`io`** or **`none`**. When selecting **`none`**

Documentation/NetworkBoot.md

@@ -175,7 +175,6 @@ Don't forget to replace `X.Y.Z.W` with your HTTP server IP address.
 
 For troubleshooting purposes, you can add the following command line arguments if you suspect our implementation fails to work with your hardware:
 - `disable_physical_storage`
-- `disable_ps2_controller`
 - `disable_uhci_controller`
 
 Because iPXE (unlike GRUB) doesn't support VESA VBE modesetting when booting a multiboot kernel,

Kernel/Arch/x86_64/ISABus/I8042Controller.cpp

@@ -107,23 +107,12 @@ UNMAP_AFTER_INIT ErrorOr<void> I8042Controller::detect_devices()
 
         TRY(do_wait_then_write(I8042Port::Command, I8042Command::ReadConfiguration));
         configuration = TRY(do_wait_then_read(I8042Port::Buffer));
-        TRY(do_wait_then_write(I8042Port::Command, I8042Command::WriteConfiguration));
         configuration &= ~I8042ConfigurationFlag::FirstPS2PortInterrupt;
         configuration &= ~I8042ConfigurationFlag::SecondPS2PortInterrupt;
-
-        // Note: The default BIOS on the QEMU microvm machine type (qboot) doesn't
-        // behave like SeaBIOS, which means it doesn't set first port scan code translation.
-        // However we rely on compatibility feature of the i8042 to send scan codes of set 1.
-        // To ensure that the controller is always outputting correct scan codes, set it
-        // to scan code 2 (because SeaBIOS on regular QEMU machine does this for us) and enable
-        // first port translation to ensure all scan codes are translated to scan code set 1.
         configuration |= I8042ConfigurationFlag::FirstPS2PortTranslation;
-        TRY(do_wait_then_write(I8042Port::Buffer, configuration));
-        TRY(do_wait_then_write(I8042Port::Buffer, I8042Command::SetScanCodeSet));
-        TRY(do_wait_then_write(I8042Port::Buffer, 0x2));
 
-        m_is_dual_channel = (configuration & I8042ConfigurationFlag::SecondPS2PortClock) != 0;
-        dbgln("I8042: {} channel controller", m_is_dual_channel ? "Dual" : "Single");
+        TRY(do_wait_then_write(I8042Port::Command, I8042Command::WriteConfiguration));
+        TRY(do_wait_then_write(I8042Port::Buffer, configuration));
 
         // Perform controller self-test
         TRY(do_wait_then_write(I8042Port::Command, I8042Command::TestPS2Controller));
@@ -134,8 +123,12 @@ UNMAP_AFTER_INIT ErrorOr<void> I8042Controller::detect_devices()
             TRY(do_wait_then_write(I8042Port::Buffer, configuration));
         } else {
             dbgln("I8042: Controller self test failed");
+            return Error::from_errno(EIO);
         }
 
+        m_is_dual_channel = (configuration & I8042ConfigurationFlag::SecondPS2PortClock) != 0;
+        dbgln("I8042: {} channel controller", m_is_dual_channel ? "Dual" : "Single");
+
         // Test ports and enable them if available
         TRY(do_wait_then_write(I8042Port::Command, I8042Command::TestFirstPS2Port));
         auto first_port_test_result = TRY(do_wait_then_read(I8042Port::Buffer));

Kernel/CommandLine.cpp

@@ -139,6 +139,20 @@ UNMAP_AFTER_INIT bool CommandLine::is_early_boot_console_disabled() const
     PANIC("Unknown early_boot_console setting: {}", value);
 }
 
+UNMAP_AFTER_INIT I8042PresenceMode CommandLine::i8042_presence_mode() const
+{
+    auto value = lookup("i8042_presence_mode"sv).value_or("auto"sv);
+    if (value == "auto"sv)
+        return I8042PresenceMode::Automatic;
+    if (value == "none"sv)
+        return I8042PresenceMode::None;
+    if (value == "force"sv)
+        return I8042PresenceMode::Force;
+    if (value == "aggressive-test"sv)
+        return I8042PresenceMode::AggressiveTest;
+    PANIC("Unknown i8042_presence_mode setting: {}", value);
+}
+
 UNMAP_AFTER_INIT bool CommandLine::is_vmmouse_enabled() const
 {
     return lookup("vmmouse"sv).value_or("on"sv) == "on"sv;
@@ -220,11 +234,6 @@ UNMAP_AFTER_INIT bool CommandLine::is_physical_networking_disabled() const
     return contains("disable_physical_networking"sv);
 }
 
-UNMAP_AFTER_INIT bool CommandLine::disable_ps2_controller() const
-{
-    return contains("disable_ps2_controller"sv);
-}
-
 UNMAP_AFTER_INIT bool CommandLine::disable_physical_storage() const
 {
     return contains("disable_physical_storage"sv);

Kernel/CommandLine.h

@@ -24,6 +24,13 @@ enum class HPETMode {
     NonPeriodic
 };
 
+enum class I8042PresenceMode {
+    Automatic,
+    AggressiveTest,
+    Force,
+    None,
+};
+
 enum class AcpiFeatureLevel {
     Enabled,
     Limited,
@@ -77,13 +84,13 @@ public:
     [[nodiscard]] bool is_legacy_time_enabled() const;
     [[nodiscard]] bool is_pc_speaker_enabled() const;
     [[nodiscard]] GraphicsSubsystemMode graphics_subsystem_mode() const;
+    [[nodiscard]] I8042PresenceMode i8042_presence_mode() const;
     [[nodiscard]] bool is_force_pio() const;
     [[nodiscard]] AcpiFeatureLevel acpi_feature_level() const;
     [[nodiscard]] StringView system_mode() const;
     [[nodiscard]] PanicMode panic_mode(Validate should_validate = Validate::No) const;
     [[nodiscard]] HPETMode hpet_mode() const;
     [[nodiscard]] bool disable_physical_storage() const;
-    [[nodiscard]] bool disable_ps2_controller() const;
     [[nodiscard]] bool disable_uhci_controller() const;
     [[nodiscard]] bool disable_usb() const;
     [[nodiscard]] bool disable_virtio() const;
@@ -93,6 +100,7 @@ public:
     [[nodiscard]] NonnullOwnPtrVector<KString> userspace_init_args() const;
     [[nodiscard]] StringView root_device() const;
     [[nodiscard]] bool is_nvme_polling_enabled() const;
+    [[nodiscard]] bool is_i8042_force_scan_code_2() const;
     [[nodiscard]] size_t switch_to_tty() const;
 
 private:

Kernel/Devices/HID/HIDManagement.cpp

@@ -120,24 +120,39 @@ UNMAP_AFTER_INIT ErrorOr<void> HIDManagement::enumerate()
     // emulation of the PS/2 controller if it was set by the BIOS.
     // If ACPI indicates we have an i8042 controller and the USB controller was
     // set to emulate PS/2, we should not initialize the PS/2 controller.
-    if (kernel_command_line().disable_ps2_controller())
-        return {};
 #if ARCH(X86_64)
-    m_i8042_controller = I8042Controller::initialize();
-
-    // Note: If ACPI is disabled or doesn't indicate that we have an i8042, we
-    // still perform a manual existence check via probing, which is relevant on
-    // QEMU, for example. This probing check is known to not work on bare metal
-    // in all cases, so if we can get a 'yes' from ACPI, we skip it.
     auto has_i8042_controller = false;
-    if (ACPI::Parser::the() && ACPI::Parser::the()->have_8042())
-        has_i8042_controller = true;
-    else if (m_i8042_controller->check_existence_via_probing({}))
+    auto i8042_controller = I8042Controller::initialize();
+    switch (kernel_command_line().i8042_presence_mode()) {
+    case I8042PresenceMode::Automatic: {
+        // Note: If ACPI is disabled or doesn't indicate that we have an i8042, we
+        // still perform a manual existence check via probing, which is relevant on
+        // QEMU, for example. This probing check is known to not work on bare metal
+        // in all cases, so if we can get a 'yes' from ACPI, we skip it.
+        if (ACPI::Parser::the() && ACPI::Parser::the()->have_8042())
+            has_i8042_controller = true;
+        else if (i8042_controller->check_existence_via_probing({}))
+            has_i8042_controller = true;
+        break;
+    }
+    case I8042PresenceMode::Force: {
         has_i8042_controller = true;
+        break;
+    }
+    case I8042PresenceMode::None: {
+        break;
+    }
+    case I8042PresenceMode::AggressiveTest: {
+        if (i8042_controller->check_existence_via_probing({}))
+            has_i8042_controller = true;
+        break;
+    }
+    }
 
     // Note: If we happen to not have i8042 just return "gracefully" for now.
     if (!has_i8042_controller)
         return {};
+    m_i8042_controller = i8042_controller;
     TRY(m_i8042_controller->detect_devices());
     if (m_i8042_controller->mouse())
         m_hid_devices.append(m_i8042_controller->mouse().release_nonnull());