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Kernel: Finish base implementation of VirtQueues
This commit includes a lot of small changes and additions needed to finalize the base implementation of VirtIOQueues and VirtDevices: * The device specific driver implementation now has to handle setting up the queues it needs before letting the base device class know it finised initialization * Supplying buffers to VirtQueues is now done via ScatterGatherLists instead of arbitary buffer pointers - this ensures the pointers are physical and allows us to follow the specification in regards to the requirement that individual descriptors must point to physically contiguous buffers. This can be further improved in the future by implementating support for the Indirect-Descriptors feature (as defined by the specification) to reduce descriptor usage for very fragmented buffers. * When supplying buffers to a VirtQueue the driver must supply a (temporarily-)unique token (usually the supplied buffer's virtual address) to ensure the driver can discern which buffer has finished processing by the device in the case in which the device does not offer the F_IN_ORDER feature. * Device drivers now handle queue updates (supplied buffers being returned from the device) by implementing a single pure virtual method instead of setting a seperate callback for each queue * Two new VirtQueue methods were added to allow the device driver to either discard or get used/returned buffers from the device by cleanly removing them off the descriptor chain (This also allows the VirtQueue implementation to reuse those freed descriptors) This also includes the necessary changes to the VirtIOConsole implementation to match these interface changes. Co-authored-by: Sahan <sahan.h.fernando@gmail.com>
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7 changed files with 154 additions and 85 deletions
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@ -1,5 +1,5 @@
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/*
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* Copyright (c) 2020, the SerenityOS developers.
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* Copyright (c) 2021, the SerenityOS developers.
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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@ -123,7 +123,7 @@ auto VirtIODevice::mapping_for_bar(u8 bar) -> MappedMMIO&
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void VirtIODevice::notify_queue(u16 queue_index)
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{
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dbgln("VirtIODevice: notifying about queue change at idx: {}", queue_index);
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dbgln_if(VIRTIO_DEBUG, "{}: notifying about queue change at idx: {}", m_class_name, queue_index);
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if (!m_notify_cfg)
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out<u16>(REG_QUEUE_NOTIFY, queue_index);
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else
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@ -207,9 +207,7 @@ bool VirtIODevice::accept_device_features(u64 device_features, u64 accepted_feat
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m_did_accept_features = true;
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if (is_feature_set(device_features, VIRTIO_F_VERSION_1)) {
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accepted_features |= VIRTIO_F_VERSION_1;
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} else {
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dbgln_if(VIRTIO_DEBUG, "{}: legacy device detected", m_class_name);
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accepted_features |= VIRTIO_F_VERSION_1; // let the device know were not a legacy driver
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}
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if (is_feature_set(device_features, VIRTIO_F_RING_PACKED)) {
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@ -217,6 +215,11 @@ bool VirtIODevice::accept_device_features(u64 device_features, u64 accepted_feat
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accepted_features &= ~(VIRTIO_F_RING_PACKED);
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}
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// TODO: implement indirect descriptors to allow queue_size buffers instead of buffers totalling (PAGE_SIZE * queue_size) bytes
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if (is_feature_set(device_features, VIRTIO_F_INDIRECT_DESC)) {
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// accepted_features |= VIRTIO_F_INDIRECT_DESC;
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}
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if (is_feature_set(device_features, VIRTIO_F_IN_ORDER)) {
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accepted_features |= VIRTIO_F_IN_ORDER;
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}
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@ -301,21 +304,24 @@ bool VirtIODevice::activate_queue(u16 queue_index)
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return true;
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}
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void VirtIODevice::set_requested_queue_count(u16 count)
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bool VirtIODevice::setup_queues(u16 requested_queue_count)
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{
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m_queue_count = count;
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}
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VERIFY(!m_did_setup_queues);
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m_did_setup_queues = true;
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bool VirtIODevice::setup_queues()
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{
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if (m_common_cfg) {
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auto maximum_queue_count = config_read16(*m_common_cfg, COMMON_CFG_NUM_QUEUES);
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if (m_queue_count == 0) {
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if (requested_queue_count == 0) {
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m_queue_count = maximum_queue_count;
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} else if (m_queue_count > maximum_queue_count) {
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} else if (requested_queue_count > maximum_queue_count) {
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dbgln("{}: {} queues requested but only {} available!", m_class_name, m_queue_count, maximum_queue_count);
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return false;
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} else {
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m_queue_count = requested_queue_count;
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}
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} else {
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m_queue_count = requested_queue_count;
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dbgln("{}: device's available queue count could not be determined!", m_class_name);
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}
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dbgln_if(VIRTIO_DEBUG, "{}: Setting up {} queues", m_class_name, m_queue_count);
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@ -330,23 +336,20 @@ bool VirtIODevice::setup_queues()
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return true;
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}
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bool VirtIODevice::finish_init()
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void VirtIODevice::finish_init()
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{
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VERIFY(m_did_accept_features);
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VERIFY(!(m_status & DEVICE_STATUS_DRIVER_OK));
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if (!setup_queues()) {
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dbgln("{}: Failed to setup queues", m_class_name);
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return false;
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}
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VERIFY(m_did_accept_features); // ensure features were negotiated
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VERIFY(m_did_setup_queues); // ensure queues were set-up
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VERIFY(!(m_status & DEVICE_STATUS_DRIVER_OK)); // ensure we didnt already finish the initialization
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set_status_bit(DEVICE_STATUS_DRIVER_OK);
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dbgln_if(VIRTIO_DEBUG, "{}: Finished initialization", m_class_name);
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return true;
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}
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void VirtIODevice::supply_buffer_and_notify(u16 queue_index, const u8* buffer, u32 len, BufferType buffer_type)
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void VirtIODevice::supply_buffer_and_notify(u16 queue_index, const ScatterGatherList& scatter_list, BufferType buffer_type, void* token)
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{
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VERIFY(queue_index < m_queue_count);
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if (get_queue(queue_index).supply_buffer({}, buffer, len, buffer_type))
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if (get_queue(queue_index).supply_buffer({}, scatter_list, buffer_type, token))
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notify_queue(queue_index);
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}
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@ -367,10 +370,11 @@ void VirtIODevice::handle_irq(const RegisterState&)
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}
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}
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if (isr_type & QUEUE_INTERRUPT) {
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for (auto& queue : m_queues) {
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if (queue.handle_interrupt())
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return;
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for (size_t i = 0; i < m_queues.size(); i++) {
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if (get_queue(i).new_data_available())
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return handle_queue_update(i);
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}
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dbgln_if(VIRTIO_DEBUG, "{}: Got queue interrupt but all queues are up to date!", m_class_name);
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}
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if (isr_type & ~(QUEUE_INTERRUPT | DEVICE_CONFIG_INTERRUPT))
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dbgln("{}: Handling interrupt with unknown type: {}", m_class_name, isr_type);
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