kernel/linux.git/include/linux/vfio_pci_core.h, branch v6.12.80

vfio/pci: Disable qword access to the PCI ROM bar

2026-01-08T09:15:05+00:00

[ Upstream commit dc85a46928c41423ad89869baf05a589e2975575 ] Commit 2b938e3db335 ("vfio/pci: Enable iowrite64 and ioread64 for vfio pci") enables qword access to the PCI bar resources. However certain devices (e.g. Intel X710) are observed with problem upon qword accesses to the rom bar, e.g. triggering PCI aer errors. This is triggered by Qemu which caches the rom content by simply does a pread() of the remaining size until it gets the full contents. The other bars would only perform operations at the same access width as their guest drivers. Instead of trying to identify all broken devices, universally disable qword access to the rom bar i.e. going back to the old way which worked reliably for years. Reported-by: Farrah Chen Closes: https://bugzilla.kernel.org/show_bug.cgi?id=220740 Fixes: 2b938e3db335 ("vfio/pci: Enable iowrite64 and ioread64 for vfio pci") Cc: stable@vger.kernel.org Signed-off-by: Kevin Tian Tested-by: Farrah Chen Link: https://lore.kernel.org/r/20251218081650.555015-2-kevin.tian@intel.com Signed-off-by: Alex Williamson Signed-off-by: Greg Kroah-Hartman

vfio/pci: Use RCU for error/request triggers to avoid circular locking

2025-12-18T12:55:12+00:00

[ Upstream commit 98693e0897f754e3f51ce6626ed5f785f625ba2b ] Thanks to a device generating an ACS violation during bus reset, lockdep reported the following circular locking issue: CPU0: SET_IRQS (MSI/X): holds igate, acquires memory_lock CPU1: HOT_RESET: holds memory_lock, acquires pci_bus_sem CPU2: AER: holds pci_bus_sem, acquires igate This results in a potential 3-way deadlock. Remove the pci_bus_sem->igate leg of the triangle by using RCU to peek at the eventfd rather than locking it with igate. Fixes: 3be3a074cf5b ("vfio-pci: Don't use device_lock around AER interrupt setup") Signed-off-by: Alex Williamson Reviewed-by: Jason Gunthorpe Link: https://lore.kernel.org/r/20251124223623.2770706-1-alex@shazbot.org Signed-off-by: Alex Williamson Signed-off-by: Sasha Levin

vfio/pci: Fix typo in macro to declare accessors

2024-06-21T18:47:01+00:00

Correct spelling of DECLA[RA]TION Suggested-by: Ramesh Thomas Signed-off-by: Gerd Bayer Link: https://lore.kernel.org/r/20240619115847.1344875-4-gbayer@linux.ibm.com Signed-off-by: Alex Williamson

vfio/pci: Support 8-byte PCI loads and stores

2024-06-21T18:47:01+00:00

Many PCI adapters can benefit or even require full 64bit read and write access to their registers. In order to enable work on user-space drivers for these devices add two new variations vfio_pci_core_io{read|write}64 of the existing access methods when the architecture supports 64-bit ioreads and iowrites. Signed-off-by: Ben Segal Co-developed-by: Gerd Bayer Signed-off-by: Gerd Bayer Link: https://lore.kernel.org/r/20240619115847.1344875-3-gbayer@linux.ibm.com Signed-off-by: Alex Williamson

vfio/pci: Use unmap_mapping_range()

2024-05-31T21:15:51+00:00

With the vfio device fd tied to the address space of the pseudo fs inode, we can use the mm to track all vmas that might be mmap'ing device BARs, which removes our vma_list and all the complicated lock ordering necessary to manually zap each related vma. Note that we can no longer store the pfn in vm_pgoff if we want to use unmap_mapping_range() to zap a selective portion of the device fd corresponding to BAR mappings. This also converts our mmap fault handler to use vmf_insert_pfn() because we no longer have a vma_list to avoid the concurrency problem with io_remap_pfn_range(). The goal is to eventually use the vm_ops huge_fault handler to avoid the additional faulting overhead, but vmf_insert_pfn_{pmd,pud}() need to learn about pfnmaps first. Also, Jason notes that a race exists between unmap_mapping_range() and the fops mmap callback if we were to call io_remap_pfn_range() to populate the vma on mmap. Specifically, mmap_region() does call_mmap() before it does vma_link_file() which gives a window where the vma is populated but invisible to unmap_mapping_range(). Suggested-by: Jason Gunthorpe Reviewed-by: Jason Gunthorpe Reviewed-by: Kevin Tian Link: https://lore.kernel.org/r/20240530045236.1005864-3-alex.williamson@redhat.com Signed-off-by: Alex Williamson

vfio/pci: rename and export range_intersect_range

2024-02-22T19:20:20+00:00

range_intersect_range determines an overlap between two ranges. If an overlap, the helper function returns the overlapping offset and size. The VFIO PCI variant driver emulates the PCI config space BAR offset registers. These offset may be accessed for read/write with a variety of lengths including sub-word sizes from sub-word offsets. The driver makes use of this helper function to read/write the targeted part of the emulated register. Make this a vfio_pci_core function, rename and export as GPL. Also update references in virtio driver. Reviewed-by: Kevin Tian Reviewed-by: Yishai Hadas Signed-off-by: Ankit Agrawal Link: https://lore.kernel.org/r/20240220115055.23546-3-ankita@nvidia.com Signed-off-by: Alex Williamson

vfio/pci: rename and export do_io_rw()

2024-02-22T19:20:20+00:00

do_io_rw() is used to read/write to the device MMIO. The grace hopper VFIO PCI variant driver require this functionality to read/write to its memory. Rename this as vfio_pci_core functions and export as GPL. Reviewed-by: Kevin Tian Reviewed-by: Yishai Hadas Signed-off-by: Ankit Agrawal Link: https://lore.kernel.org/r/20240220115055.23546-2-ankita@nvidia.com Signed-off-by: Alex Williamson

vfio/pci: Expose vfio_pci_core_iowrite/read##size()

2023-12-19T18:51:33+00:00

Expose vfio_pci_core_iowrite/read##size() to let it be used by drivers. This functionality is needed to enable direct access to some physical BAR of the device with the proper locks/checks in place. The next patches from this series will use this functionality on a data path flow when a direct access to the BAR is needed. Reviewed-by: Jason Gunthorpe Reviewed-by: Kevin Tian Signed-off-by: Yishai Hadas Acked-by: Michael S. Tsirkin Link: https://lore.kernel.org/r/20231219093247.170936-9-yishaih@nvidia.com Signed-off-by: Alex Williamson

vfio/pci: Expose vfio_pci_core_setup_barmap()

2023-12-19T18:51:33+00:00

Expose vfio_pci_core_setup_barmap() to be used by drivers. This will let drivers to mmap a BAR and re-use it from both vfio and the driver when it's applicable. This API will be used in the next patches by the vfio/virtio coming driver. Reviewed-by: Jason Gunthorpe Reviewed-by: Kevin Tian Signed-off-by: Yishai Hadas Acked-by: Michael S. Tsirkin Link: https://lore.kernel.org/r/20231219093247.170936-8-yishaih@nvidia.com Signed-off-by: Alex Williamson

vfio/pci: Probe and store ability to support dynamic MSI-X

2023-05-23T21:49:03+00:00

Not all MSI-X devices support dynamic MSI-X allocation. Whether a device supports dynamic MSI-X should be queried using pci_msix_can_alloc_dyn(). Instead of scattering code with pci_msix_can_alloc_dyn(), probe this ability once and store it as a property of the virtual device. Suggested-by: Alex Williamson Signed-off-by: Reinette Chatre Reviewed-by: Kevin Tian Acked-by: Thomas Gleixner Reviewed-by: Jason Gunthorpe Link: https://lore.kernel.org/r/f1ae022c060ecb7e527f4f53c8ccafe80768da47.1683740667.git.reinette.chatre@intel.com Signed-off-by: Alex Williamson