Re: [dpdk-dev] [PATCH] pci/linux: use RTE_IOVA_VA whenever possible

[Alejandro Lucero <alejandro.lucero@netronome.com>]

On Fri, Sep 7, 2018 at 3:55 PM Darek Stojaczyk <dariusz.stojaczyk@intel.com>
wrote:

> This allows DPDK to use RTE_IOVA_VA with VFIO/UIO-bound PCI
> devices present on the system, but not attached to any
> rte_pci_driver at the time of init.
>
> So far we used RTE_IOVA_VA whenever there was at least one
> device attached to a driver with an RTE_PCI_DRV_IOVA_AS_VA flag,
> meaning that other drivers which didn't explicitly report such
> flag could have been forced to work in RTE_IOVA_VA as well.
>

This is the opposite. Just one device not being able to use IOVA VA makes
all to use IOVA PA.


>
> This patch makes the RTE_PCI_DRV_IOVA_AS_VA explicitly a hint.
> If it's set, but RTE_IOVA_VA cannot be used, then EAL will print
> a proper warning.
>
> Signed-off-by: Darek Stojaczyk <dariusz.stojaczyk@intel.com>
> ---
>  drivers/bus/pci/linux/pci.c | 11 +++++------
>  1 file changed, 5 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/bus/pci/linux/pci.c b/drivers/bus/pci/linux/pci.c
> index 04648ac93..961e24024 100644
> --- a/drivers/bus/pci/linux/pci.c
> +++ b/drivers/bus/pci/linux/pci.c
> @@ -534,7 +534,7 @@ pci_one_device_bound_uio(void)
>   * Any one of the device has iova as va
>   */
>  static inline int
> -pci_one_device_has_iova_va(void)
> +pci_one_device_want_iova_va(void)
>  {
>         struct rte_pci_device *dev = NULL;
>         struct rte_pci_driver *drv = NULL;
> @@ -635,7 +635,7 @@ rte_pci_get_iommu_class(void)
>  {
>         bool is_bound;
>         bool is_vfio_noiommu_enabled = true;
> -       bool has_iova_va;
> +       bool want_iova_va;
>         bool is_bound_uio;
>         bool iommu_no_va;
>
> @@ -643,7 +643,7 @@ rte_pci_get_iommu_class(void)
>         if (!is_bound)
>                 return RTE_IOVA_DC;
>
> -       has_iova_va = pci_one_device_has_iova_va();
> +       want_iova_va = pci_one_device_want_iova_va();
>         is_bound_uio = pci_one_device_bound_uio();
>         iommu_no_va = !pci_devices_iommu_support_va();
>  #ifdef VFIO_PRESENT
> @@ -651,11 +651,10 @@ rte_pci_get_iommu_class(void)
>                                         true : false;
>  #endif
>
> -       if (has_iova_va && !is_bound_uio && !is_vfio_noiommu_enabled &&
> -                       !iommu_no_va)
> +       if (!is_bound_uio && !is_vfio_noiommu_enabled && !iommu_no_va)
>                 return RTE_IOVA_VA;
>

This is wrong. A device not able to work with IOVA VA will fail.


>
> -       if (has_iova_va) {
> +       if (want_iova_va) {
>                 RTE_LOG(WARNING, EAL, "Some devices want iova as va but pa
> will be used because.. ");
>                 if (is_vfio_noiommu_enabled)
>                         RTE_LOG(WARNING, EAL, "vfio-noiommu mode
> configured\n");
> --
> 2.17.1
>
>