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

[Thomas Monjalon <thomas@monjalon.net>]

11/10/2018 12:47, Jerin Jacob:
> -----Original Message-----
> > Date: Thu, 11 Oct 2018 11:26:05 +0100
> > From: "Burakov, Anatoly" <anatoly.burakov@intel.com>
> > To: Alejandro Lucero <alejandro.lucero@netronome.com>,
> >  dariusz.stojaczyk@intel.com
> > CC: dev <dev@dpdk.org>, Santosh Shukla <santosh.shukla@caviumnetworks.com>,
> >  Hemant Agrawal <hemant.agrawal@nxp.com>, Jerin Jacob
> >  <jerin.jacob@caviumnetworks.com>, Maxime Coquelin
> >  <maxime.coquelin@redhat.com>, chas3@att.com
> > Subject: Re: [dpdk-dev] [PATCH] pci/linux: use RTE_IOVA_VA whenever possible
> > User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:52.0) Gecko/20100101
> >  Thunderbird/52.9.1
> > 
> > 
> > On 11-Oct-18 11:00 AM, Alejandro Lucero wrote:
> > > 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
> > > > 
> > > > 
> > > 
> > 
> > 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.
> 
> Yes.

Patch marked as rejected