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

[Burakov, Anatoly]

On 11-Oct-18 11:00 AM, Alejandro Lucero wrote:
On Fri, Sep 7, 2018 at 3:55 PM Darek Stojaczyk <dariusz.stojac...@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.stojac...@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




For these cases, i think the explicit IOVA mode on command line should 
work better. If the device has not reported IOVA as VA capability, it is 
to be assumed unsupported.

--
Thanks,
Anatoly