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/*
* Copyright (c) 2021, the SerenityOS developers.
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include <Kernel/Bus/VirtIO/RNG.h>
#include <Kernel/Sections.h>
namespace Kernel::VirtIO {
UNMAP_AFTER_INIT NonnullRefPtr<RNG> RNG::must_create(PCI::DeviceIdentifier const& device_identifier)
{
return adopt_ref_if_nonnull(new RNG(device_identifier)).release_nonnull();
}
UNMAP_AFTER_INIT void RNG::initialize()
{
Device::initialize();
bool success = negotiate_features([&](auto) {
return 0;
});
if (success) {
success = setup_queues(1);
}
if (success) {
finish_init();
m_entropy_buffer = MM.allocate_contiguous_kernel_region(PAGE_SIZE, "VirtIO::RNG", Memory::Region::Access::ReadWrite).release_value();
if (m_entropy_buffer) {
memset(m_entropy_buffer->vaddr().as_ptr(), 0, m_entropy_buffer->size());
request_entropy_from_host();
}
}
}
UNMAP_AFTER_INIT RNG::RNG(PCI::DeviceIdentifier const& device_identifier)
: VirtIO::Device(device_identifier)
{
}
bool RNG::handle_device_config_change()
{
return false; // Device has no config
}
void RNG::handle_queue_update(u16 queue_index)
{
VERIFY(queue_index == REQUESTQ);
size_t available_entropy = 0, used;
auto& queue = get_queue(REQUESTQ);
{
SpinlockLocker lock(queue.lock());
auto chain = queue.pop_used_buffer_chain(used);
if (chain.is_empty())
return;
VERIFY(chain.length() == 1);
chain.for_each([&available_entropy](PhysicalAddress, size_t length) {
available_entropy = length;
});
chain.release_buffer_slots_to_queue();
}
dbgln_if(VIRTIO_DEBUG, "VirtIO::RNG: received {} bytes of entropy!", available_entropy);
for (auto i = 0u; i < available_entropy; i++) {
m_entropy_source.add_random_event(m_entropy_buffer->vaddr().as_ptr()[i]);
}
// TODO: When should we get some more entropy?
}
void RNG::request_entropy_from_host()
{
auto& queue = get_queue(REQUESTQ);
SpinlockLocker lock(queue.lock());
QueueChain chain(queue);
chain.add_buffer_to_chain(m_entropy_buffer->physical_page(0)->paddr(), PAGE_SIZE, BufferType::DeviceWritable);
supply_chain_and_notify(REQUESTQ, chain);
}
}
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