Hi all, Per PCIe r6.3, sec 10.3.1 IMPLEMENTATION NOTE, software should disable ATS before initiating a Function Level Reset, and then ensure no invalidation requests being issued to a device when its ATS capability is disabled. Both pci_enable_ats() and pci_disable_ats() are called by an IOMMU driver, but an unsolicited FLR can happen at any time in the PCI layer. This might result in a race between them, breaking the rules given by the PCIe Spec. Therefore, there needs to be a sync between IOMMU and PCI subsystems, to ensure that ATS will be disabled and never gets re-enabled until the FLR finishes. Add a pair of new IOMMU helpers for PCI reset functions to call before and after the reset routines. These two helpers will temporally attach the device's RID/PASID to IOMMU_DOMAIN_BLOCKED, which should allow its IOMMU driver to pause any DMA traffic and disable ATS feature until the FLR is done. This is on Github: https://github.com/nicolinc/iommufd/commits/iommu_dev_reset-rfcv1 Thanks Nicolin Nicolin Chen (2): iommu: Introduce iommu_dev_reset_prepare() and iommu_dev_reset_done() pci: Suspend ATS before doing FLR include/linux/iommu.h | 12 +++++ drivers/iommu/iommu.c | 106 ++++++++++++++++++++++++++++++++++++++++++ drivers/pci/pci.c | 42 +++++++++++++++-- 3 files changed, 156 insertions(+), 4 deletions(-) -- 2.43.0
