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Kernel: Improve context state keeping in the VirtIOGPU3DDevice class

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This is done mainly by implementing safe locking on the data structure
keeping the pointers to the PerContextState objects. Therefore, this now
eliminates the need for using LockRefPtr, as SpinlockProtected is enough
for the whole list.

The usage of HashMap in this class was questionable, and according to
Sahan Fernando (the original contributor to the VirGL work also known as
ccapitalK) there was no deep research on which data structure to use for
keeping all pointers to PerContextState objects.
Therefore, this structure is changed to IntrusiveList as the main reason
and advantage to use it is that handling OOM conditions is much more
simple, because if we succeeded to create a PerContextState object, we
can be sure now that inserting it to the list will not cause OOM error
condition.
This commit is contained in:
Liav A 2023-04-14 18:11:46 +03:00 • committed by Jelle Raaijmakers
parent 8289759f1d
commit 7b6cea9ef4
2 changed files with 88 additions and 54 deletions
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25
Kernel/Graphics/VirtIOGPU/GPU3DDevice.h
View file

@ -7,9 +7,11 @@
#pragma once
#include <AK/DistinctNumeric.h>
#include <AK/IntrusiveList.h>
#include <Kernel/Devices/CharacterDevice.h>
#include <Kernel/Devices/DeviceManagement.h>
#include <Kernel/Graphics/VirtIOGPU/Protocol.h>
#include <Kernel/Locking/SpinlockProtected.h>
namespace Kernel::Graphics::VirtIOGPU {
@ -101,24 +103,35 @@ private:
VirtIOGPU3DDevice(VirtIOGraphicsAdapter const& graphics_adapter, NonnullOwnPtr<Memory::Region> transfer_buffer_region, Graphics::VirtIOGPU::ContextID kernel_context_id);
class PerContextState final : public AtomicRefCounted<PerContextState> {
friend class VirtIOGPU3DDevice;
public:
static ErrorOr<LockRefPtr<PerContextState>> try_create(Graphics::VirtIOGPU::ContextID context_id)
static ErrorOr<NonnullRefPtr<PerContextState>> try_create(OpenFileDescription& description, Graphics::VirtIOGPU::ContextID context_id)
{
auto region_result = TRY(MM.allocate_kernel_region(
NUM_TRANSFER_REGION_PAGES * PAGE_SIZE,
"VIRGL3D userspace upload buffer"sv,
Memory::Region::Access::ReadWrite,
AllocationStrategy::AllocateNow));
return TRY(adopt_nonnull_lock_ref_or_enomem(new (nothrow) PerContextState(context_id, move(region_result))));
return TRY(adopt_nonnull_ref_or_enomem(new (nothrow) PerContextState(description, context_id, move(region_result))));
}
Graphics::VirtIOGPU::ContextID context_id() { return m_context_id; }
Memory::Region& transfer_buffer_region() { return *m_transfer_buffer_region; }
OpenFileDescription& description() { return m_attached_file_description; }
private:
PerContextState() = delete;
explicit PerContextState(Graphics::VirtIOGPU::ContextID context_id, OwnPtr<Memory::Region> transfer_buffer_region);
PerContextState(OpenFileDescription&, Graphics::VirtIOGPU::ContextID context_id, OwnPtr<Memory::Region> transfer_buffer_region);
Graphics::VirtIOGPU::ContextID m_context_id;
OwnPtr<Memory::Region> m_transfer_buffer_region;
// NOTE: We clean this whole object when the file description is closed, therefore we need to hold
// a raw reference here instead of a strong reference pointer (e.g. RefPtr, which will make it
// possible to leak the attached OpenFileDescription for a context in this device).
OpenFileDescription& m_attached_file_description;
IntrusiveListNode<PerContextState, NonnullRefPtr<PerContextState>> m_list_node;
};
virtual bool can_read(OpenFileDescription const&, u64) const override { return true; }
@ -130,13 +143,13 @@ private:
virtual ErrorOr<void> ioctl(OpenFileDescription&, unsigned request, Userspace<void*> arg) override;
virtual void detach(OpenFileDescription&) override;
private:
ErrorOr<LockRefPtr<PerContextState>> get_context_for_description(OpenFileDescription&);
using ContextList = IntrusiveListRelaxedConst<&PerContextState::m_list_node>;
private:
NonnullLockRefPtr<VirtIOGraphicsAdapter> m_graphics_adapter;
// Context used for kernel operations (e.g. flushing resources to scanout)
Graphics::VirtIOGPU::ContextID m_kernel_context_id;
HashMap<OpenFileDescription*, LockRefPtr<PerContextState>> m_context_state_lookup;
SpinlockProtected<ContextList, LockRank::None> m_context_state_list;
// Memory management for backing buffers
NonnullOwnPtr<Memory::Region> m_transfer_buffer_region;
constexpr static size_t NUM_TRANSFER_REGION_PAGES = 1024;