Kernel/PCI: Hold a reference to DeviceIdentifier in the Device class

There are now 2 separate classes for almost the same object type:
- EnumerableDeviceIdentifier, which is used in the enumeration code for
  all PCI host controller classes. This is allowed to be moved and
  copied, as it doesn't support ref-counting.
- DeviceIdentifier, which inherits from EnumerableDeviceIdentifier. This
  class uses ref-counting, and is not allowed to be copied. It has a
  spinlock member in its structure to allow safely executing complicated
  IO sequences on a PCI device and its space configuration.
  There's a static method that allows a quick conversion from
  EnumerableDeviceIdentifier to DeviceIdentifier while creating a
  NonnullRefPtr out of it.

The reason for doing this is for the sake of integrity and reliablity of
the system in 2 places:
- Ensure that "complicated" tasks that rely on manipulating PCI device
  registers are done in a safe manner. For example, determining a PCI
  BAR space size requires multiple read and writes to the same register,
  and if another CPU tries to do something else with our selected
  register, then the result will be a catastrophe.
- Allow the PCI API to have a united form around a shared object which
  actually holds much more data than the PCI::Address structure. This is
  fundamental if we want to do certain types of optimizations, and be
  able to support more features of the PCI bus in the foreseeable
  future.

This patch already has several implications:
- All PCI::Device(s) hold a reference to a DeviceIdentifier structure
  being given originally from the PCI::Access singleton. This means that
  all instances of DeviceIdentifier structures are located in one place,
  and all references are pointing to that location. This ensures that
  locking the operation spinlock will take effect in all the appropriate
  places.
- We no longer support adding PCI host controllers and then immediately
  allow for enumerating it with a lambda function. It was found that
  this method is extremely broken and too much complicated to work
  reliably with the new paradigm being introduced in this patch. This
  means that for Volume Management Devices (Intel VMD devices), we
  simply first enumerate the PCI bus for such devices in the storage
  code, and if we find a device, we attach it in the PCI::Access method
  which will scan for devices behind that bridge and will add new
  DeviceIdentifier(s) objects to its internal Vector. Afterwards, we
  just continue as usual with scanning for actual storage controllers,
  so we will find a corresponding NVMe controllers if there were any
  behind that VMD bridge.

1 files changed, 15 insertions, 11 deletions

diff --git a/Kernel/Bus/PCI/Access.h b/Kernel/Bus/PCI/Access.h
index e0fd8a924b..8c5b5fcab9 100644
--- a/Kernel/Bus/PCI/Access.h
+++ b/Kernel/Bus/PCI/Access.h
@@ -9,6 +9,7 @@
 #include <AK/Bitmap.h>
 #include <AK/HashMap.h>
 #include <AK/NonnullOwnPtr.h>
+#include <AK/NonnullRefPtrVector.h>
 #include <AK/Try.h>
 #include <AK/Vector.h>
 #include <Kernel/Bus/PCI/Controller/HostController.h>
@@ -33,22 +34,25 @@ public:
     static bool is_disabled();
     static bool is_hardware_disabled();
 
-    void write8_field(Address address, u32 field, u8 value);
-    void write16_field(Address address, u32 field, u16 value);
-    void write32_field(Address address, u32 field, u32 value);
-    u8 read8_field(Address address, u32 field);
-    u16 read16_field(Address address, u32 field);
-    u32 read32_field(Address address, u32 field);
-    DeviceIdentifier get_device_identifier(Address address) const;
+    void write8_field(DeviceIdentifier const&, u32 field, u8 value);
+    void write16_field(DeviceIdentifier const&, u32 field, u16 value);
+    void write32_field(DeviceIdentifier const&, u32 field, u32 value);
+    u8 read8_field(DeviceIdentifier const&, u32 field);
+    u16 read16_field(DeviceIdentifier const&, u32 field);
+    u32 read32_field(DeviceIdentifier const&, u32 field);
+
+    // FIXME: Remove this once we can use PCI::Capability with inline buffer
+    // so we don't need this method
+    DeviceIdentifier const& get_device_identifier(Address address) const;
 
     Spinlock<LockRank::None> const& scan_lock() const { return m_scan_lock; }
     RecursiveSpinlock<LockRank::None> const& access_lock() const { return m_access_lock; }
 
-    ErrorOr<void> add_host_controller_and_enumerate_attached_devices(NonnullOwnPtr<HostController>, Function<void(DeviceIdentifier const&)> callback);
+    ErrorOr<void> add_host_controller_and_scan_for_devices(NonnullOwnPtr<HostController>);
 
 private:
-    u8 read8_field(Address address, RegisterOffset field);
-    u16 read16_field(Address address, RegisterOffset field);
+    u8 read8_field(DeviceIdentifier const&, RegisterOffset field);
+    u16 read16_field(DeviceIdentifier const&, RegisterOffset field);
 
     void add_host_controller(NonnullOwnPtr<HostController>);
     bool find_and_register_pci_host_bridges_from_acpi_mcfg_table(PhysicalAddress mcfg);
@@ -61,6 +65,6 @@ private:
     mutable Spinlock<LockRank::None> m_scan_lock {};
 
     HashMap<u32, NonnullOwnPtr<PCI::HostController>> m_host_controllers;
-    Vector<DeviceIdentifier> m_device_identifiers;
+    NonnullRefPtrVector<DeviceIdentifier> m_device_identifiers;
 };
 }