On Sat, Oct 10, 2026 at 05:25:25PM +0800, [email protected] wrote: > From: liufeng1 <[email protected]> > > Add a new PCI driver flag, RTE_PCI_DRV_NEED_IOVA_AS_PA, that allows a > driver to tell the PCI bus layer 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. > > Signed-off-by: Jie Liu <[email protected]> > --- > 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(-) > > diff --git a/drivers/bus/pci/bus_pci_driver.h > b/drivers/bus/pci/bus_pci_driver.h > index c04ebddf59..5d5efbbb3e 100644 > --- a/drivers/bus/pci/bus_pci_driver.h > +++ b/drivers/bus/pci/bus_pci_driver.h > @@ -140,6 +140,8 @@ struct rte_pci_driver { > #define RTE_PCI_DRV_KEEP_MAPPED_RES 0x0020 > /** Device driver needs IOVA as VA and cannot work with IOVA as PA */ > #define RTE_PCI_DRV_NEED_IOVA_AS_VA 0x0040 > +/** Device driver needs IOVA as PA and cannot work with IOVA as VA */ > +#define RTE_PCI_DRV_NEED_IOVA_AS_PA 0x0080 > > /** > * Register a PCI driver. > diff --git a/drivers/bus/pci/linux/pci.c b/drivers/bus/pci/linux/pci.c > index bcf0a409da..bf7125e214 100644 > --- a/drivers/bus/pci/linux/pci.c > +++ b/drivers/bus/pci/linux/pci.c > @@ -609,6 +609,8 @@ pci_device_iova_mode(const struct rte_pci_driver *pdrv, > iova_mode = RTE_IOVA_PA; > else if ((pdrv->drv_flags & RTE_PCI_DRV_NEED_IOVA_AS_VA) != 0) > iova_mode = RTE_IOVA_VA; > + else if ((pdrv->drv_flags & RTE_PCI_DRV_NEED_IOVA_AS_PA) != 0) > + iova_mode = RTE_IOVA_PA; > break; > } > > @@ -620,6 +622,8 @@ pci_device_iova_mode(const struct rte_pci_driver *pdrv, > default: > if ((pdrv->drv_flags & RTE_PCI_DRV_NEED_IOVA_AS_VA) != 0) > iova_mode = RTE_IOVA_VA; > + else if ((pdrv->drv_flags & RTE_PCI_DRV_NEED_IOVA_AS_PA) != 0) > + iova_mode = RTE_IOVA_PA; > break; > } > return iova_mode;
Do we need a sanity check somewhere that we don't have two drivers with conflicting flags set i.e. one NEED_IOVA_AS_VA and one NEED_IOVA_AS_PA? It should never happen, I imagine, but things that should never happen have this annoying habit of sometimes happening! :-) /Bruce
