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https://github.com/RGBCube/serenity
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ed6c1f53af
This ensures we safely handle interrupts (which can call virtual functions), so they don't happen in the constructor - this pattern can lead to a crash, if we are still in the constructor context because not all methods are available for usage (some are pure virtual, so it's possible to call __cxa_pure_virtual). Also, under some conditions like adding a PCI device via PCI-passthrough mechanism in QEMU, it became exposed to the eye that the code asserts on RNG::handle_device_config_change(). That device has no configuration but if the hypervisor still misbehaves and tries to configure it, we should simply return false to indicate nothing happened.
78 lines
2.2 KiB
C++
78 lines
2.2 KiB
C++
/*
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* Copyright (c) 2021, the SerenityOS developers.
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*
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* SPDX-License-Identifier: BSD-2-Clause
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*/
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#include <Kernel/Bus/VirtIO/RNG.h>
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#include <Kernel/Sections.h>
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namespace Kernel::VirtIO {
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UNMAP_AFTER_INIT NonnullRefPtr<RNG> RNG::must_create(PCI::Address address)
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{
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return adopt_ref_if_nonnull(new RNG(address)).release_nonnull();
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}
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UNMAP_AFTER_INIT void RNG::initialize()
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{
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Device::initialize();
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bool success = negotiate_features([&](auto) {
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return 0;
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});
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if (success) {
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success = setup_queues(1);
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}
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if (success) {
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finish_init();
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m_entropy_buffer = MM.allocate_contiguous_kernel_region(PAGE_SIZE, "VirtIO::RNG", Memory::Region::Access::ReadWrite);
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if (m_entropy_buffer) {
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memset(m_entropy_buffer->vaddr().as_ptr(), 0, m_entropy_buffer->size());
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request_entropy_from_host();
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}
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}
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}
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UNMAP_AFTER_INIT RNG::RNG(PCI::Address address)
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: VirtIO::Device(address)
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{
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}
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bool RNG::handle_device_config_change()
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{
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return false; // Device has no config
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}
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void RNG::handle_queue_update(u16 queue_index)
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{
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VERIFY(queue_index == REQUESTQ);
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size_t available_entropy = 0, used;
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auto& queue = get_queue(REQUESTQ);
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{
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SpinlockLocker lock(queue.lock());
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auto chain = queue.pop_used_buffer_chain(used);
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if (chain.is_empty())
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return;
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VERIFY(chain.length() == 1);
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chain.for_each([&available_entropy](PhysicalAddress, size_t length) {
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available_entropy = length;
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});
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chain.release_buffer_slots_to_queue();
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}
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dbgln_if(VIRTIO_DEBUG, "VirtIO::RNG: received {} bytes of entropy!", available_entropy);
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for (auto i = 0u; i < available_entropy; i++) {
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m_entropy_source.add_random_event(m_entropy_buffer->vaddr().as_ptr()[i]);
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}
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// TODO: When should we get some more entropy?
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}
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void RNG::request_entropy_from_host()
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{
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auto& queue = get_queue(REQUESTQ);
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SpinlockLocker lock(queue.lock());
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QueueChain chain(queue);
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chain.add_buffer_to_chain(m_entropy_buffer->physical_page(0)->paddr(), PAGE_SIZE, BufferType::DeviceWritable);
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supply_chain_and_notify(REQUESTQ, chain);
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}
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}
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