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Kernel/PCI: Introduce a new ECAM access mechanism

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Now the kernel supports 2 ECAM access methods.
MMIOAccess was renamed to WindowedMMIOAccess and is what we had until
now - each device that is detected on boot is assigned to a
memory-mapped window, so IO operations on multiple devices can occur
simultaneously due to creating multiple virtual mappings, hence the name
is a memory-mapped window.

This commit adds a new class called MMIOAccess (not to be confused with
the old MMIOAccess class). This class creates one memory-mapped window.
On each IO operation on a configuration space of a device, it maps the
requested PCI bus region to that window. Therefore it holds a SpinLock
during the operation to ensure that no other PCI bus region was mapped
during the call.

A user can choose to either use PCI ECAM with memory-mapped window
for each device, or for an entire bus. By default, the kernel prefers to
map the entire PCI bus region.
This commit is contained in:
Liav A 2021-04-03 16:46:04 +03:00 • committed by Andreas Kling
parent 441e374396
commit 8abbb7e090
11 changed files with 320 additions and 100 deletions
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8
Kernel/CommandLine.cpp
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@ -108,13 +108,15 @@ UNMAP_AFTER_INIT bool CommandLine::is_vmmouse_enabled() const
return lookup("vmmouse").value_or("on") == "on";
}
UNMAP_AFTER_INIT bool CommandLine::is_pci_ecam_enabled() const
UNMAP_AFTER_INIT PCIAccessLevel CommandLine::pci_access_level() const
{
auto value = lookup("pci_ecam").value_or("on");
if (value == "on")
return true;
return PCIAccessLevel::MappingPerBus;
if (value == "per-device")
return PCIAccessLevel::MappingPerDevice;
if (value == "off")
return false;
return PCIAccessLevel::IOAddressing;
PANIC("Unknown PCI ECAM setting: {}", value);
}