Thomas Monjalon <tho...@monjalon.net> wrote on 11/03/2017 11:28:10 AM:
> From: Thomas Monjalon <tho...@monjalon.net> > To: Jonas Pfefferle1 <j...@zurich.ibm.com> > Cc: acon...@redhat.com, anatoly.bura...@intel.com, > bruce.richard...@intel.com, dev@dpdk.org, gaetan.ri...@6wind.com, > hemant.agra...@nxp.com, jerin.ja...@caviumnetworks.com, > maxime.coque...@redhat.com, olivier.m...@6wind.com, Santosh Shukla > <santosh.shu...@caviumnetworks.com>, > sergio.gonzalez.mon...@intel.com, shreyansh.j...@nxp.com, > step...@networkplumber.org, Alexey Kardashevskiy <a...@ozlabs.ru> > Date: 11/03/2017 11:28 AM > Subject: Re: [dpdk-dev] [PATCH v7 7/9] linuxapp/eal_vfio: honor iova > mode before mapping > > 03/11/2017 10:56, Jonas Pfefferle1: > > Thomas Monjalon <tho...@monjalon.net> wrote on 11/02/2017 11:17:10 AM: > > > > 26/10/2017 14:57, Jonas Pfefferle1: > > > > > > > > > > Hi @all > > > > > > > > > > I just stumbled upon this patch while testing on POWER. RTE_IOVA_VA > > > will > > > > > not work for the sPAPR code since the dma window size is currently > > > > > determined by the physical address only. > > > > > > > > Is it affecting POWER8? > > > > > > It is. > > > > > > > > > > > > I'm preparing a patch to address this. > > > > > > > > Any news? > > > > Can you use virtual addresses? > > > > > > After a long discussion with Alexey (CC) we came to the conclusion that > > > with the current sPAPR iommu driver we cannot use virtual addresses since > > > the iova is restricted to lay in the DMA window which itself is > > restricted > > > to physical RAM addresses resp. with the current code 0 to hotplug memory > > > max. However, Alexey is working on a patch to lift this restriction on > > the > > > DMA window size which should allow us to do VA:VA mappings in the future. > > > For now we should fall back to PA in the dynamic iova mode check. I will > > > send an according patch later today. > > > > I looked into this yesterday but I'm not sure what the right solution is > > here. > > At the time rte_pci_get_iommu_class is called we already know which IOMMU > > types are supported because vfio_get_container_fd resp. > > vfio_has_supported_extensions has been called however we do not know which > > one is going to be used (Decided later in vfio_setup_device resp. > > vfio_set_iommu_type). We can choose a iova mode which is supported by all > > types but if the modes are exclusive to the types we have to guess which > > one is going to be used. Or let the user decide? > > You can keep the old behaviour, restricting to physical memory, > until you support virtual addressing. > It can be just a #ifdef RTE_ARCH_PPC_64. > Ok but we might want to refine this in the future. IMO It looks much cleaner to decide this on the iommu type plus this would also cover the noiommu case without having this extra check reading the sysfs variable.
