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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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42
Kernel/VirtIO/VirtIOConsole.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
@ -24,12 +24,15 @@
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include <Kernel/VM/ScatterGatherList.h>
#include <Kernel/VirtIO/VirtIOConsole.h>
namespace Kernel {
unsigned VirtIOConsole::next_device_id = 0;
VirtIOConsole::VirtIOConsole(PCI::Address address)
: CharacterDevice(229, 0)
: CharacterDevice(229, next_device_id++)
, VirtIODevice(address, "VirtIOConsole")
{
if (auto cfg = get_config(ConfigurationType::Device)) {
@ -54,22 +57,15 @@ VirtIOConsole::VirtIOConsole(PCI::Address address)
}
});
dbgln("VirtIOConsole: cols: {}, rows: {}, max nr ports {}", cols, rows, max_nr_ports);
set_requested_queue_count(2 + max_nr_ports * 2); // base receiveq/transmitq for port0 + 2 per every additional port
success = finish_init();
success = setup_queues(2 + max_nr_ports * 2); // base receiveq/transmitq for port0 + 2 per every additional port
}
if (success) {
get_queue(RECEIVEQ).on_data_available = [&]() {
dbgln("VirtIOConsole: receive_queue on_data_available");
};
finish_init();
m_receive_region = MM.allocate_contiguous_kernel_region(PAGE_SIZE, "VirtIOConsole Receive", Region::Access::Read | Region::Access::Write);
if (m_receive_region) {
supply_buffer_and_notify(RECEIVEQ, m_receive_region->physical_page(0)->paddr().as_ptr(), m_receive_region->size(), BufferType::DeviceWritable);
supply_buffer_and_notify(RECEIVEQ, ScatterGatherList::create_from_physical(m_receive_region->physical_page(0)->paddr(), m_receive_region->size()), BufferType::DeviceWritable, m_receive_region->vaddr().as_ptr());
}
get_queue(TRANSMITQ).on_data_available = [&]() {
dbgln("VirtIOConsole: send_queue on_data_available");
};
m_transmit_region = MM.allocate_contiguous_kernel_region(PAGE_SIZE, "VirtIOConsole Transmit", Region::Access::Read | Region::Access::Write);
dbgln("TODO: Populate receive queue with a receive buffer");
}
}
}
@ -84,6 +80,21 @@ bool VirtIOConsole::handle_device_config_change()
return true;
}
void VirtIOConsole::handle_queue_update(u16 queue_index)
{
VERIFY(queue_index <= TRANSMITQ);
switch (queue_index) {
case RECEIVEQ:
get_queue(RECEIVEQ).discard_used_buffers(); // TODO: do something with incoming data (users writing into qemu console) instead of just clearing
break;
case TRANSMITQ:
get_queue(TRANSMITQ).discard_used_buffers(); // clear outgoing buffers that the device finished with
break;
default:
VERIFY_NOT_REACHED();
}
}
bool VirtIOConsole::can_read(const FileDescription&, size_t) const
{
return false;
@ -106,12 +117,9 @@ KResultOr<size_t> VirtIOConsole::write(FileDescription&, u64, const UserOrKernel
{
if (!size)
return 0;
VERIFY(size <= PAGE_SIZE);
if (!data.read(m_transmit_region->vaddr().as_ptr(), size)) {
return Kernel::KResult((ErrnoCode)-EFAULT);
}
supply_buffer_and_notify(TRANSMITQ, m_transmit_region->physical_page(0)->paddr().as_ptr(), size, BufferType::DeviceReadable);
auto scatter_list = ScatterGatherList::create_from_buffer(static_cast<const u8*>(data.user_or_kernel_ptr()), size);
supply_buffer_and_notify(TRANSMITQ, scatter_list, BufferType::DeviceReadable, const_cast<void*>(data.user_or_kernel_ptr()));
return size;
}