From 2e9a28272e790d36ee398ba7ab9934b82231ba18 Mon Sep 17 00:00:00 2001
From: Vladimir Serbinenko <phcoder@gmail.com>
Date: Sat, 22 Jul 2023 20:45:59 +0200
Subject: [PATCH] Kernel/Audio: Fail AC97 probe if no good BAR1 is found

Otherwise we get a kernel panic later on Intel SOF.
---
 Kernel/Devices/Audio/AC97/AC97.cpp | 15 +++++++++++++++
 Kernel/Devices/Audio/AC97/AC97.h   |  2 ++
 2 files changed, 17 insertions(+)

diff --git a/Kernel/Devices/Audio/AC97/AC97.cpp b/Kernel/Devices/Audio/AC97/AC97.cpp
index bd30caee72..f505a0a58f 100644
--- a/Kernel/Devices/Audio/AC97/AC97.cpp
+++ b/Kernel/Devices/Audio/AC97/AC97.cpp
@@ -35,6 +35,21 @@ UNMAP_AFTER_INIT ErrorOr<NonnullRefPtr<AudioController>> AC97::create(PCI::Devic
 UNMAP_AFTER_INIT ErrorOr<bool> AC97::probe(PCI::DeviceIdentifier const& device_identifier)
 {
     VERIFY(device_identifier.class_code() == PCI::ClassID::Multimedia);
+
+    // TODO: Check pci ids.
+
+    if (PCI::get_BAR_space_size(device_identifier, PCI::HeaderType0BaseRegister::BAR0) <= NativeAudioMixerRegister::MaxUsedMixerOffset)
+        return Error::from_errno(EIO);
+
+    // BAR registers are 32-bit. So if BAR0 is 64-bit then
+    // it occupies BAR0 and BAR1 and hence BAR1 isn't present on its own.
+    u64 pci_bar0_value = PCI::get_BAR(device_identifier, PCI::HeaderType0BaseRegister::BAR0);
+    if (PCI::get_BAR_space_type(pci_bar0_value) == PCI::BARSpaceType::Memory64BitSpace)
+        return Error::from_errno(EIO);
+
+    if (PCI::get_BAR_space_size(device_identifier, PCI::HeaderType0BaseRegister::BAR1) <= NativeAudioBusRegister::MaxUsedBusOffset)
+        return Error::from_errno(EIO);
+
     return device_identifier.subclass_code() == PCI::Multimedia::SubclassID::Audio;
 }
 
diff --git a/Kernel/Devices/Audio/AC97/AC97.h b/Kernel/Devices/Audio/AC97/AC97.h
index 1b0ab9aecb..bf072dd8e1 100644
--- a/Kernel/Devices/Audio/AC97/AC97.h
+++ b/Kernel/Devices/Audio/AC97/AC97.h
@@ -48,6 +48,7 @@ private:
         PCMFrontDACRate = 0x2c,
         VendorID1 = 0x7c,
         VendorID2 = 0x7e,
+        MaxUsedMixerOffset = 0x7f,
     };
 
     enum ExtendedAudioMask : u16 {
@@ -79,6 +80,7 @@ private:
 
     enum NativeAudioBusRegister : u8 {
         GlobalControl = 0x2c,
+        MaxUsedBusOffset = 0x2f
     };
 
     enum AudioStatusRegisterFlag : u16 {