kernel/linux.git/drivers/pci/msi, branch v6.3

PCI/MSI: Remove over-zealous hardware size check in pci_msix_validate_entries()

2023-04-16T12:11:51+00:00

pci_msix_validate_entries() validates the entries array which is handed in by the caller for a MSI-X interrupt allocation. Aside of consistency failures it also detects a failure when the size of the MSI-X hardware table in the device is smaller than the size of the entries array. That's wrong for the case of range allocations where the caller provides the minimum and the maximum number of vectors to allocate, when the hardware size is greater or equal than the mininum, but smaller than the maximum. Remove the hardware size check completely from that function and just ensure that the entires array up to the maximum size is consistent. The limitation and range checking versus the hardware size happens independently of that afterwards anyway because the entries array is optional. Fixes: 4644d22eb673 ("PCI/MSI: Validate MSI-X contiguous restriction early") Reported-by: David Laight Signed-off-by: Thomas Gleixner Cc: stable@vger.kernel.org Link: https://lore.kernel.org/r/87v8i3sg62.ffs@tglx

PCI/MSI: Clarify usage of pci_msix_free_irq()

2023-02-21T07:25:14+00:00

pci_msix_free_irq() is used to free an interrupt on a PCI/MSI-X interrupt domain. The API description specifies that the interrupt to be freed was allocated via pci_msix_alloc_irq_at(). This description limits the usage of pci_msix_free_irq() since pci_msix_free_irq() can also be used to free MSI-X interrupts allocated with, for example, pci_alloc_irq_vectors(). Remove the text stating that the interrupt to be freed had to be allocated with pci_msix_alloc_irq_at(). The needed struct msi_map need not be from pci_msix_alloc_irq_at() but can be created from scratch using pci_irq_vector() to obtain the Linux IRQ number. Highlight that pci_msix_free_irq() cannot be used to disable MSI-X to guide users that, for example, pci_free_irq_vectors() remains to be needed. Signed-off-by: Reinette Chatre Signed-off-by: Thomas Gleixner Reviewed-by: Kevin Tian Link: https://lore.kernel.org/lkml/87r0xsd8j4.ffs@tglx Link: https://lore.kernel.org/r/4c3e7a50d6e70f408812cd7ab199c6b4b326f9de.1676408572.git.reinette.chatre@intel.com

PCI/MSI: Provide pci_ims_alloc/free_irq()

2022-12-05T21:22:35+00:00

Single vector allocation which allocates the next free index in the IMS space. The free function releases. All allocated vectors are released also via pci_free_vectors() which is also releasing MSI/MSI-X vectors. Signed-off-by: Thomas Gleixner Reviewed-by: Kevin Tian Acked-by: Bjorn Helgaas Acked-by: Marc Zyngier Link: https://lore.kernel.org/r/20221124232326.961711347@linutronix.de

PCI/MSI: Provide IMS (Interrupt Message Store) support

2022-12-05T21:22:34+00:00

IMS (Interrupt Message Store) is a new specification which allows implementation specific storage of MSI messages contrary to the strict standard specified MSI and MSI-X message stores. This requires new device specific interrupt domains to handle the implementation defined storage which can be an array in device memory or host/guest memory which is shared with hardware queues. Add a function to create IMS domains for PCI devices. IMS domains are using the new per device domain mechanism and are configured by the device driver via a template. IMS domains are created as secondary device domains so they work side on side with MSI[-X] on the same device. The IMS domains have a few constraints: - The index space is managed by the core code. Device memory based IMS provides a storage array with a fixed size which obviously requires an index. But there is no association between index and functionality so the core can randomly allocate an index in the array. System memory based IMS does not have the concept of an index as the storage is somewhere in memory. In that case the index is purely software based to keep track of the allocations. - There is no requirement for consecutive index ranges This is currently a limitation of the MSI core and can be implemented if there is a justified use case by changing the internal storage from xarray to maple_tree. For now it's single vector allocation. - The interrupt chip must provide the following callbacks: - irq_mask() - irq_unmask() - irq_write_msi_msg() - The interrupt chip must provide the following optional callbacks when the irq_mask(), irq_unmask() and irq_write_msi_msg() callbacks cannot operate directly on hardware, e.g. in the case that the interrupt message store is in queue memory: - irq_bus_lock() - irq_bus_unlock() These callbacks are invoked from preemptible task context and are allowed to sleep. In this case the mandatory callbacks above just store the information. The irq_bus_unlock() callback is supposed to make the change effective before returning. - Interrupt affinity setting is handled by the underlying parent interrupt domain and communicated to the IMS domain via irq_write_msi_msg(). IMS domains cannot have a irq_set_affinity() callback. That's a reasonable restriction similar to the PCI/MSI device domain implementations. The domain is automatically destroyed when the PCI device is removed. Signed-off-by: Thomas Gleixner Reviewed-by: Kevin Tian Acked-by: Marc Zyngier Link: https://lore.kernel.org/r/20221124232326.904316841@linutronix.de

PCI/MSI: Provide post-enable dynamic allocation interfaces for MSI-X

2022-12-05T21:22:34+00:00

MSI-X vectors can be allocated after the initial MSI-X enablement, but this needs explicit support of the underlying interrupt domains. Provide a function to query the ability and functions to allocate/free individual vectors post-enable. The allocation can either request a specific index in the MSI-X table or with the index argument MSI_ANY_INDEX it allocates the next free vector. The return value is a struct msi_map which on success contains both index and the Linux interrupt number. In case of failure index is negative and the Linux interrupt number is 0. The allocation function is for a single MSI-X index at a time as that's sufficient for the most urgent use case VFIO to get rid of the 'disable MSI-X, reallocate, enable-MSI-X' cycle which is prone to lost interrupts and redirections to the legacy and obviously unhandled INTx. As single index allocation is also sufficient for the use cases Jason Gunthorpe pointed out: Allocation of a MSI-X or IMS vector for a network queue. See Link below. Signed-off-by: Thomas Gleixner Reviewed-by: Kevin Tian Acked-by: Bjorn Helgaas Acked-by: Marc Zyngier Link: https://lore.kernel.org/all/20211126232735.547996838@linutronix.de Link: https://lore.kernel.org/r/20221124232326.731233614@linutronix.de

PCI/MSI: Provide prepare_desc() MSI domain op

2022-12-05T21:22:34+00:00

The setup of MSI descriptors for PCI/MSI-X interrupts depends partially on the MSI index for which the descriptor is initialized. Dynamic MSI-X vector allocation post MSI-X enablement allows to allocate vectors at a given index or at any free index in the available table range. The latter requires that the descriptor is initialized after the MSI core has chosen an index. Implement the prepare_desc() op in the PCI/MSI-X specific msi_domain_ops which is invoked before the core interrupt descriptor and the associated Linux interrupt number is allocated. That callback is also provided for the upcoming PCI/IMS implementations so the implementation specific interrupt domain can do their domain specific initialization of the MSI descriptors. Signed-off-by: Thomas Gleixner Reviewed-by: Jason Gunthorpe Reviewed-by: Kevin Tian Acked-by: Bjorn Helgaas Acked-by: Marc Zyngier Link: https://lore.kernel.org/r/20221124232326.673658806@linutronix.de

PCI/MSI: Split MSI-X descriptor setup

2022-12-05T21:22:34+00:00

The upcoming mechanism to allocate MSI-X vectors after enabling MSI-X needs to share some of the MSI-X descriptor setup. The regular descriptor setup on enable has the following code flow: 1) Allocate descriptor 2) Setup descriptor with PCI specific data 3) Insert descriptor 4) Allocate interrupts which in turn scans the inserted descriptors This cannot be easily changed because the PCI/MSI code needs to handle the legacy architecture specific allocation model and the irq domain model where quite some domains have the assumption that the above flow is how it works. Ideally the code flow should look like this: 1) Invoke allocation at the MSI core 2) MSI core allocates descriptor 3) MSI core calls back into the irq domain which fills in the domain specific parts This could be done for underlying parent MSI domains which support post-enable allocation/free but that would create significantly different code pathes for MSI/MSI-X enable. Though for dynamic allocation which wants to share the allocation code with the upcoming PCI/IMS support it's the right thing to do. Split the MSI-X descriptor setup into the preallocation part which just sets the index and fills in the horrible hack of virtual IRQs and the real PCI specific MSI-X setup part which solely depends on the index in the descriptor. This allows to provide a common dynamic allocation interface at the MSI core level for both PCI/MSI-X and PCI/IMS. Signed-off-by: Thomas Gleixner Reviewed-by: Kevin Tian Acked-by: Bjorn Helgaas Acked-by: Marc Zyngier Link: https://lore.kernel.org/r/20221124232326.616292598@linutronix.de

PCI/MSI: Remove unused pci_dev_has_special_msi_domain()

2022-12-05T21:22:33+00:00

The check for special MSI domains like VMD which prevents the interrupt remapping code to overwrite device::msi::domain is not longer required and has been replaced by an x86 specific version which is aware of MSI parent domains. Remove it. Signed-off-by: Thomas Gleixner Reviewed-by: Kevin Tian Acked-by: Bjorn Helgaas Acked-by: Marc Zyngier Link: https://lore.kernel.org/r/20221124232326.093093200@linutronix.de

PCI/MSI: Add support for per device MSI[X] domains

2022-12-05T21:22:32+00:00

Provide a template and the necessary callbacks to create PCI/MSI and PCI/MSI-X domains. The domains are created when MSI or MSI-X is enabled. The domain's lifetime is either the device lifetime or in case that e.g. MSI-X was tried first and failed, then the MSI-X domain is removed and a MSI domain is created as both are mutually exclusive and reside in the default domain ID slot of the per device domain pointer array. Also expand pci_msi_domain_supports() to handle feature checks correctly even in the case that the per device domain was not yet created by checking the features supported by the MSI parent. Add the necessary setup calls into the MSI and MSI-X enable code path. These setup calls are backwards compatible. They return success when there is no parent domain found, which means the existing global domains or the legacy allocation path keep just working. Co-developed-by: Ahmed S. Darwish Signed-off-by: Ahmed S. Darwish Signed-off-by: Thomas Gleixner Reviewed-by: Kevin Tian Acked-by: Bjorn Helgaas Acked-by: Marc Zyngier Link: https://lore.kernel.org/r/20221124232325.975388241@linutronix.de

PCI/MSI: Split __pci_write_msi_msg()

2022-12-05T21:22:32+00:00

The upcoming per device MSI domains will create different domains for MSI and MSI-X. Split the write message function into MSI and MSI-X helpers so they can be used by those new domain functions seperately. Signed-off-by: Ahmed S. Darwish Signed-off-by: Thomas Gleixner Reviewed-by: Kevin Tian Acked-by: Bjorn Helgaas Acked-by: Marc Zyngier Link: https://lore.kernel.org/r/20221124232325.857982142@linutronix.de