From: liufeng1 <[email protected]> This series adds a new PCI driver flag, RTE_PCI_DRV_NEED_IOVA_AS_PA, which allows a PCI driver to tell the PCI bus layer that it cannot work with IOVA as VA and must use IOVA as PA.
The existing RTE_PCI_DRV_NEED_IOVA_AS_VA flag already provides the opposite requirement. Some PCI devices, however, are managed by a kernel driver that uses an identity-mapped IOMMU domain (e.g. when the kernel is booted with iommu=pt). The user-space PMD for such devices must use IOVA as PA, because the DMA addresses programmed by DPDK must match the identity mapping programmed by the kernel driver. Without this flag, a PCI driver bound to a non-VFIO/UIO kernel driver has no way to force IOVA as PA. pci_device_iova_mode() returns RTE_IOVA_DC for those devices, and rte_eal_init() then sees an enabled IOMMU and selects RTE_IOVA_VA, which breaks identity-domain PMDs and forces users to pass --iova-mode=pa on the command line. When RTE_PCI_DRV_NEED_IOVA_AS_PA is set, pci_device_iova_mode() returns RTE_IOVA_PA for the device. The requirement is propagated through rte_pci_get_iommu_class() to rte_bus_get_iommu_class(), so rte_eal_init() selects IOVA as PA automatically. This is a generic mechanism: any PCI driver whose underlying kernel driver uses an identity IOMMU domain can set the flag. liufeng1 (1): bus/pci: add RTE_PCI_DRV_NEED_IOVA_AS_PA flag drivers/bus/pci/bus_pci_driver.h | 2 ++ drivers/bus/pci/linux/pci.c | 4 ++++ drivers/bus/pci/pci_common.c | 3 +-- 3 files changed, 7 insertions(+), 2 deletions(-) -- 2.52.0
