kernel.git/drivers/pci/setup-bus.c, branch linux-6.15.y

PCI: Restore assigned resources fully after release

2025-04-18T13:23:22Z

PCI resource fitting code in __assign_resources_sorted() runs in multiple steps. A resource that was successfully assigned may have to be released before the next step attempts assignment again. The assign+release cycle is destructive to a start-aligned struct resource (bridge window or IOV resource) because the start field is overwritten with the real address when the resource got assigned. One symptom: pci 0002:00:00.0: bridge window [mem size 0x00100000]: can't assign; bogus alignment Properly restore the resource after releasing it. The start, end, and flags fields must be stored into the related struct pci_dev_resource in order to be able to restore the resource to its original state. Fixes: 96336ec70264 ("PCI: Perform reset_resource() and build fail list in sync") Reported-by: Guenter Roeck Closes: https://lore.kernel.org/r/01eb7d40-f5b5-4ec5-b390-a5c042c30aff@roeck-us.net/ Reported-by: Nicolas Frattaroli Closes: https://lore.kernel.org/r/3578030.5fSG56mABF@workhorse Signed-off-by: Ilpo Järvinen Signed-off-by: Bjorn Helgaas Tested-by: Nicolas Frattaroli Tested-by: Guenter Roeck Tested-by: Ondrej Jirman Link: https://patch.msgid.link/20250403093137.1481-1-ilpo.jarvinen@linux.intel.com

Merge branch 'pci/misc'

2025-03-27T18:15:05Z

- Remove unused tools 'pci' build target left over after moving tests to tools/testing/selftests/pci_endpoint (Jianfeng Liu) - Fix typos and whitespace errors (Bjorn Helgaas) * pci/misc: PCI: Fix typos tools/Makefile: Remove pci target # Conflicts: # drivers/pci/endpoint/functions/pci-epf-test.c

PCI: Make pci_setup_bridge() static

2025-03-20T21:44:26Z

pci_setup_bridge() is only used within setup-bus.c. Therefore, make it a static function. Link: https://lore.kernel.org/r/20250311174701.3586-3-ilpo.jarvinen@linux.intel.com Signed-off-by: Ilpo Järvinen Signed-off-by: Bjorn Helgaas

PCI: Fix typos

2025-03-08T21:08:45Z

Fix typos and whitespace errors. Link: https://lore.kernel.org/r/20250307231715.438518-1-helgaas@kernel.org Signed-off-by: Bjorn Helgaas

PCI: Increase Resizable BAR support from 512 GB to 128 TB

2025-03-07T17:23:34Z

Per PCIe r6.0, sec 7.8.6.2, devices can advertise Resizable BAR sizes up to 128 TB in the Resizable BAR Capability register. Larger sizes can be advertised via the Capability register, but that requires an API change. Update pci_rebar_get_possible_sizes() and pbus_size_mem() to increase the sizes we currently support from 512 GB to 128 TB. Link: https://lore.kernel.org/r/20250307053535.44918-1-daizhiyuan@phytium.com.cn Signed-off-by: Zhiyuan Dai Signed-off-by: Bjorn Helgaas

PCI: Rework optional resource handling

2025-02-18T21:40:54Z

Remove and rescan cycle can result in failure to assign a bridge window if it becomes larger than before the remove. The bridge window size will include space for disabled Expansion ROM, which can causes the bridge window to not fit anymore into the same address space slot on rescan if the Expansion ROM resource was not assigned before the remove. In addition, the optional resource handling is not internally consistent. The resource fitting logic supports three main types of optional resources: - IOV BARs - Expansion ROMs - Bridge window size variation due to optional resources In addition to the above, resizable BARs beyond their current size will require handling optional variation in resource sizes within the resource fitting algorithm (not yet done by the resource fitting code). There are multiple inconsistencies related to optional resource handling: a) The allocation failure of disabled expansion ROM requires special case inside assign_requested_resources_sorted(). b) The optionality of disabled expansion ROM is not considered during bridge window sizing in pbus_size_mem(). c) Setting resource size to zero for optional resource in pbus_size_mem() is problematic because it makes also the alignment invalid, which is checked by pdev_sort_resources(). Optional IOV resources have their size set to zero by pbus_size_mem() but the information about size is stored externally in struct pci_sriov and complex call-chain trickery in pci_resource_alignment() ensures IOV resources return a valid alignment despite having zero resource size. A solution that is specific to IOV resources makes it hard to use the same solution for other types of resources such as expansion ROM. Simply changing pbus_size_mem() is not sufficient to fully address the main issue because it would introduce disparity between bridge window sizing and resource allocation. Due to size-based ordering of the resource list during assignment loop, an Expansion ROM resource could steal space from some other resource and make the other resource not fit if the Expansion ROM is larger than the other resource. Thus, the resource assignment functions need to be changed as well. Make optional resource handling more straightforward. Use pci_resource_is_optional() to determine if a resource is optional in both bridge window sizing and assignment failure classification to ensure they always align. Indicate with a parameter to assign_requested_resources_sorted() whether it should attempt to allocate optional resources or not. Always try first to assign all resources (also when realloc_head is not provided). This is required for calls from pci_assign_unassigned_root_bus_resources() that provide realloc_head only with some of its iterations. Non-bridge-window optional resources in realloc_head now have add_size 0. This condition has to be detected in reassign_resources_sorted() before reassigning them (which would fail as there is no size change). Removing add_size=0 optional resources entirely from realloc_head might eventually be doable but further rework in __assign_resources_sorted() is needed first to support such a change. Link: https://lore.kernel.org/r/20241216175632.4175-26-ilpo.jarvinen@linux.intel.com Reported-by: Jia Yao Closes: https://bugzilla.kernel.org/show_bug.cgi?id=219547 Signed-off-by: Ilpo Järvinen Signed-off-by: Bjorn Helgaas Tested-by: Jia Yao Tested-by: Xiaochun Lee

PCI: Perform reset_resource() and build fail list in sync

2025-02-18T21:40:54Z

Resetting a resource is problematic as it prevents attempting to allocate the resource later, unless something in between restores the resource. Similarly, if fail_head does not contain all resources that were reset, those resources cannot be restored later. The entire reset/restore cycle adds complexity and leaving resources in the reset state causes issues to other code such as for checks done in pci_enable_resources(). Take a small step towards not resetting resources by delaying reset until the end of resource assignment and build failure list (fail_head) in sync with the reset to avoid leaving behind resources that cannot be restored (for the case where the caller provides fail_head in the first place to allow restore somewhere in the callchain, as is not all callers pass non-NULL fail_head). Leave the Expansion ROM check temporarily in place while building the failure list until an upcoming change that reworks optional resource handling. Ideally, whole resource reset could be removed but doing that in one step would be non-tractable due to complexity of all related code. Link: https://lore.kernel.org/r/20241216175632.4175-25-ilpo.jarvinen@linux.intel.com Signed-off-by: Ilpo Järvinen Signed-off-by: Bjorn Helgaas Tested-by: Xiaochun Lee

PCI: Use res->parent to check if resource is assigned

2025-02-18T21:40:54Z

reassign_resources_sorted() uses resource_size() to select between pci_assign_resource() and pci_reassign_resource(). Due to twisted way bridge window sizing in pbus_size_mem() sets resource sizes to 0, it works to match into IOV resources but that is going to be changed by an upcoming change. Replace resource_size() check with res->parent check that is the true dividing line in between whether assign or reassign function should be used for the resource. Link: https://lore.kernel.org/r/20241216175632.4175-24-ilpo.jarvinen@linux.intel.com Signed-off-by: Ilpo Järvinen Signed-off-by: Bjorn Helgaas Tested-by: Xiaochun Lee

PCI: Add debug print when releasing resources before retry

2025-02-18T21:40:54Z

PCI resource fitting is somewhat hard to track because it performs many actions without logging them. In the case inside __assign_resources_sorted(), the resources are released before resource assignment is going to be retried in a different order. That is just one level of retries the resource fitting performs overall so tracking it through repeated assignments or failures of a resource gets messy rather quickly. Simply announce the release explicitly using pci_dbg() so it is clear what is going on with each resource. Link: https://lore.kernel.org/r/20241216175632.4175-23-ilpo.jarvinen@linux.intel.com Signed-off-by: Ilpo Järvinen Signed-off-by: Bjorn Helgaas Tested-by: Xiaochun Lee

PCI: Indicate optional resource assignment failures

2025-02-18T21:40:54Z

Add pci_dbg() to note that an assignment failure was for an optional resource and reword existing message about resource resize to say the change was optional. Link: https://lore.kernel.org/r/20241216175632.4175-22-ilpo.jarvinen@linux.intel.com Signed-off-by: Ilpo Järvinen Signed-off-by: Bjorn Helgaas Tested-by: Xiaochun Lee