Currently PCI hotplug works on top of resources which are usually reserved
not by the kernel, but by BIOS, bootloader, firmware, etc. These resources
are gaps in the address space where BARs of new devices may fit, and extra
bus number per port, so bridges can be hot-added. This series aim the BARs
problem: it shows the kernel how to redistribute them on the run, so the
hotplug becomes predictable and cross-platform. A follow-up patchset will
propose a solution for bus numbers.
To arrange a space for BARs of new hotplugged devices, the kernel now pause
the drivers of working PCI devices and reshuffle the assigned BARs by the
same procedure as during the system boot. When a driver is un-paused by the
kernel, it should ioremap() the new addresses of its BARs.
Drivers indicate their support of the feature by implementing the new hooks
.rescan_prepare() and .rescan_done() in the struct pci_driver. If a driver
doesn't yet support the feature, BARs of its devices will be considered as
immovable and handled in the same way as resources with the PCI_FIXED flag:
they are guaranteed to remain untouched.
Tested on a number x86_64 machines with "pci=pcie_bus_peer2peer" command
line argument to specify a policy for Maximum Payload Size PCIe setting.
Also tested on a POWER8 PowerNV+OPAL+PHB3 ppc64le machine, but with extra
patches which are to be sent upstream after the PCIPOCALYPSE patchset is
merged.
First two patches of this series are bugfixes, not related directly to the
movable BARs feature.
Patches 03-14/26 implement the essentials of the feature.
Patch 15/26 enables the feature by default.
Patches 16-26/26 are performance improvements for hotplug.
This patchset is a part of our work on adding support for hotplugging
chains of chassis full of other bridges, NVME drives, SAS HBAs, GPUs, etc.
without special requirements such as Hot-Plug Controller, reservation of
bus numbers or memory regions by firmware, etc.
Changes since v6:
- Added a fix for hotplug on AMD Epyc + Supermicro H11SSL-i by ignoring
PCIBIOS_MIN_MEM;
- Fixed a workaround which marks VGA BARs as immovables;
- Fixed misleading "can't claim BAR ... no compatible bridge window" error
messages;
- Refactored the code, reduced the amount of patches;
- Exclude PowerPC-specific arch patches, they will be sent separately;
- Disabled for PowerNV by default - waiting for the PCIPOCALYPSE patchset.
- Fixed reports from the kbuild test robot.
Changes since v5:
- Simplified the disable flag, now it is "pci=no_movable_buses";
- More deliberate marking the BARs as immovable;
- Mark as immovable BARs which are used by unbound drivers;
- Ignoring BAR assignment by non-kernel program components, so the kernel
is able now to distribute BARs in optimal and predictable way;
- Move here PowerNV-specific patches from the older "powerpc/powernv/pci:
Make hotplug self-sufficient, independent of FW and DT" series;
- Fix EEH cache rebuilding and PE allocation for PowerNV during rescan.
Changes since v4:
- Feature is enabled by default (turned on by one of the latest patches);
- Add pci_dev_movable_bars_supported(dev) instead of marking the immovable
BARs with the IORESOURCE_PCI_FIXED flag;
- Set up PCIe bridges during rescan via sysfs, so MPS settings are now
configured not only during system boot or pcihp events;
- Allow movement of switch's BARs if claimed by portdrv;
- Update EEH address caches after rescan for powerpc;
- Don't disable completely hot-added devices which can't have BARs being
fit - just disable their BARs, so they are still visible in lspci etc;
- Clearer names: fixed_range_hard -> immovable_range, fixed_range_soft ->
realloc_range;
- Drop the patch for pci_restore_config_space() - fixed by properly using
the runtime PM.
Changes since v3:
- Rebased to the upstream, so the patches apply cleanly again.
Changes since v2:
- Fixed double-assignment of bridge windows;
- Fixed assignment of fixed prefetched resources;
- Fixed releasing of fixed resources;
- Fixed a debug message;
- Removed auto-enabling the movable BARs for x86 - let's rely on the
"pcie_movable_bars=force" option for now;
- Reordered the patches - bugfixes first.
Changes since v1:
- Add a "pcie_movable_bars={ off | force }" command line argument;
- Handle the IORESOURCE_PCI_FIXED flag properly;
- Don't move BARs of devices which don't support the feature;
- Guarantee that new hotplugged devices will not steal memory from working
devices by ignoring the failing new devices with the new PCI_DEV_IGNORE
flag;
- Add rescan_prepare()+rescan_done() to the struct pci_driver instead of
using the reset_prepare()+reset_done() from struct pci_error_handlers;
- Add a bugfix of a race condition;
- Fixed hotplug in a non-pre-enabled (by BIOS/firmware) bridge;
- Fix the compatibility of the feature with pm_runtime and D3-state;
- Hotplug events from pciehp also can move BARs;
- Add support of the feature to the NVME driver.
Sergei Miroshnichenko (26):
PCI: Fix race condition in pci_enable/disable_device()
PCI: Enable bridge's I/O and MEM access for hotplugged devices
PCI: hotplug: Initial support of the movable BARs feature
PCI: Add version of release_child_resources() aware of immovable BARs
PCI: hotplug: Fix reassigning the released BARs
PCI: hotplug: Recalculate every bridge window during rescan
PCI: hotplug: Don't allow hot-added devices to steal resources
PCI: hotplug: Try to reassign movable BARs only once
PCI: hotplug: Calculate immovable parts of bridge windows
PCI: Include fixed and immovable BARs into the bus size calculating
PCI: hotplug: movable BARs: Compute limits for relocated bridge
windows
PCI: Make sure bridge windows include their fixed BARs
PCI: hotplug: Add support of immovable BARs to pci_assign_resource()
PCI: hotplug: Sort immovable BARs before assignment
PCI: hotplug: Enable the movable BARs feature by default
PCI: Ignore PCIBIOS_MIN_MEM
PCI: hotplug: Ignore the MEM BAR offsets from BIOS/bootloader
PCI: Treat VGA BARs as immovable
PCI: hotplug: Configure MPS for hot-added bridges during bus rescan
PNP: Don't reserve BARs for PCI when enabled movable BARs
PCI: hotplug: Don't disable the released bridge windows immediately
PCI: pciehp: Trigger a domain rescan on hp events when enabled movable
BARs
PCI: Don't claim immovable BARs
PCI: hotplug: Don't reserve bus space when enabled movable BARs
nvme-pci: Handle movable BARs
PCI/portdrv: Declare support of movable BARs
.../admin-guide/kernel-parameters.txt | 1 +
arch/powerpc/platforms/powernv/pci.c | 2 +
arch/powerpc/platforms/pseries/setup.c | 2 +
drivers/nvme/host/pci.c | 21 +-
drivers/pci/bus.c | 2 +-
drivers/pci/hotplug/pciehp_pci.c | 5 +
drivers/pci/pci.c | 38 +-
drivers/pci/pci.h | 31 ++
drivers/pci/pcie/portdrv_pci.c | 11 +
drivers/pci/probe.c | 331 +++++++++++++++++-
drivers/pci/setup-bus.c | 311 ++++++++++++++--
drivers/pci/setup-res.c | 47 ++-
drivers/pnp/system.c | 6 +
include/linux/pci.h | 20 ++
14 files changed, 790 insertions(+), 38 deletions(-)
base-commit: b3a6082223369203d7e7db7e81253ac761377644
--
2.24.1
