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Kernel: Finish base implementation of VirtQueues

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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>
This commit is contained in:
Idan Horowitz 2021-04-15 19:39:48 +10:00 • committed by Andreas Kling
parent acdd1424bc
commit d1f7a2f9a5
7 changed files with 154 additions and 85 deletions
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54
Kernel/VirtIO/VirtIO.cpp
View file

@ -1,5 +1,5 @@
/*
* Copyright (c) 2020, the SerenityOS developers.
* Copyright (c) 2021, the SerenityOS developers.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
@ -123,7 +123,7 @@ auto VirtIODevice::mapping_for_bar(u8 bar) -> MappedMMIO&
void VirtIODevice::notify_queue(u16 queue_index)
{
dbgln("VirtIODevice: notifying about queue change at idx: {}", queue_index);
dbgln_if(VIRTIO_DEBUG, "{}: notifying about queue change at idx: {}", m_class_name, queue_index);
if (!m_notify_cfg)
out<u16>(REG_QUEUE_NOTIFY, queue_index);
else
@ -207,9 +207,7 @@ bool VirtIODevice::accept_device_features(u64 device_features, u64 accepted_feat
m_did_accept_features = true;
if (is_feature_set(device_features, VIRTIO_F_VERSION_1)) {
accepted_features |= VIRTIO_F_VERSION_1;
} else {
dbgln_if(VIRTIO_DEBUG, "{}: legacy device detected", m_class_name);
accepted_features |= VIRTIO_F_VERSION_1; // let the device know were not a legacy driver
}
if (is_feature_set(device_features, VIRTIO_F_RING_PACKED)) {
@ -217,6 +215,11 @@ bool VirtIODevice::accept_device_features(u64 device_features, u64 accepted_feat
accepted_features &= ~(VIRTIO_F_RING_PACKED);
}
// TODO: implement indirect descriptors to allow queue_size buffers instead of buffers totalling (PAGE_SIZE * queue_size) bytes
if (is_feature_set(device_features, VIRTIO_F_INDIRECT_DESC)) {
// accepted_features |= VIRTIO_F_INDIRECT_DESC;
}
if (is_feature_set(device_features, VIRTIO_F_IN_ORDER)) {
accepted_features |= VIRTIO_F_IN_ORDER;
}
@ -301,21 +304,24 @@ bool VirtIODevice::activate_queue(u16 queue_index)
return true;
}
void VirtIODevice::set_requested_queue_count(u16 count)
bool VirtIODevice::setup_queues(u16 requested_queue_count)
{
m_queue_count = count;
}
VERIFY(!m_did_setup_queues);
m_did_setup_queues = true;
bool VirtIODevice::setup_queues()
{
if (m_common_cfg) {
auto maximum_queue_count = config_read16(*m_common_cfg, COMMON_CFG_NUM_QUEUES);
if (m_queue_count == 0) {
if (requested_queue_count == 0) {
m_queue_count = maximum_queue_count;
} else if (m_queue_count > maximum_queue_count) {
} else if (requested_queue_count > maximum_queue_count) {
dbgln("{}: {} queues requested but only {} available!", m_class_name, m_queue_count, maximum_queue_count);
return false;
} else {
m_queue_count = requested_queue_count;
}
} else {
m_queue_count = requested_queue_count;
dbgln("{}: device's available queue count could not be determined!", m_class_name);
}
dbgln_if(VIRTIO_DEBUG, "{}: Setting up {} queues", m_class_name, m_queue_count);
@ -330,23 +336,20 @@ bool VirtIODevice::setup_queues()
return true;
}
bool VirtIODevice::finish_init()
void VirtIODevice::finish_init()
{
VERIFY(m_did_accept_features);
VERIFY(!(m_status & DEVICE_STATUS_DRIVER_OK));
if (!setup_queues()) {
dbgln("{}: Failed to setup queues", m_class_name);
return false;
}
VERIFY(m_did_accept_features); // ensure features were negotiated
VERIFY(m_did_setup_queues); // ensure queues were set-up
VERIFY(!(m_status & DEVICE_STATUS_DRIVER_OK)); // ensure we didnt already finish the initialization
set_status_bit(DEVICE_STATUS_DRIVER_OK);
dbgln_if(VIRTIO_DEBUG, "{}: Finished initialization", m_class_name);
return true;
}
void VirtIODevice::supply_buffer_and_notify(u16 queue_index, const u8* buffer, u32 len, BufferType buffer_type)
void VirtIODevice::supply_buffer_and_notify(u16 queue_index, const ScatterGatherList& scatter_list, BufferType buffer_type, void* token)
{
VERIFY(queue_index < m_queue_count);
if (get_queue(queue_index).supply_buffer({}, buffer, len, buffer_type))
if (get_queue(queue_index).supply_buffer({}, scatter_list, buffer_type, token))
notify_queue(queue_index);
}
@ -367,10 +370,11 @@ void VirtIODevice::handle_irq(const RegisterState&)
}
}
if (isr_type & QUEUE_INTERRUPT) {
for (auto& queue : m_queues) {
if (queue.handle_interrupt())
return;
for (size_t i = 0; i < m_queues.size(); i++) {
if (get_queue(i).new_data_available())
return handle_queue_update(i);
}
dbgln_if(VIRTIO_DEBUG, "{}: Got queue interrupt but all queues are up to date!", m_class_name);
}
if (isr_type & ~(QUEUE_INTERRUPT | DEVICE_CONFIG_INTERRUPT))
dbgln("{}: Handling interrupt with unknown type: {}", m_class_name, isr_type);