[dpdk-dev] [PATCH v10 4/5] kni: add IOVA=VA support in KNI module

[Stephen Hemminger]

On Tue, 15 Oct 2019 16:43:08 +0100
"Yigit, Ferruh" <ferruh.yigit at linux.intel.com> wrote:

> On 8/16/2019 7:12 AM, vattunuru at marvell.com wrote:
> > From: Kiran Kumar K <kirankumark at marvell.com>
> > 
> > Patch adds support for kernel module to work in IOVA = VA mode,
> > the idea is to get physical address from IOVA address using
> > iommu_iova_to_phys API and later use phys_to_virt API to
> > convert the physical address to kernel virtual address.
> > 
> > When compared with IOVA = PA mode, there is no performance
> > drop with this approach.
> > 
> > This approach does not work with the kernel versions less
> > than 4.4.0 because of API compatibility issues.
> > 
> > Patch also updates these support details in KNI documentation.
> > 
> > Signed-off-by: Kiran Kumar K <kirankumark at marvell.com>
> > Signed-off-by: Vamsi Attunuru <vattunuru at marvell.com>  
> 
> <...>
> 
> > @@ -348,15 +351,65 @@ kni_ioctl_create(struct net *net, uint32_t ioctl_num,
> >  	strncpy(kni->name, dev_info.name, RTE_KNI_NAMESIZE);
> >  
> >  	/* Translate user space info into kernel space info */
> > -	kni->tx_q = phys_to_virt(dev_info.tx_phys);
> > -	kni->rx_q = phys_to_virt(dev_info.rx_phys);
> > -	kni->alloc_q = phys_to_virt(dev_info.alloc_phys);
> > -	kni->free_q = phys_to_virt(dev_info.free_phys);
> > -
> > -	kni->req_q = phys_to_virt(dev_info.req_phys);
> > -	kni->resp_q = phys_to_virt(dev_info.resp_phys);
> > -	kni->sync_va = dev_info.sync_va;
> > -	kni->sync_kva = phys_to_virt(dev_info.sync_phys);
> > +	if (dev_info.iova_mode) {
> > +#ifdef HAVE_IOVA_AS_VA_SUPPORT
> > +		pci = pci_get_device(dev_info.vendor_id,
> > +				     dev_info.device_id, NULL);
> > +		if (pci == NULL) {
> > +			pr_err("pci dev does not exist\n");
> > +			return -ENODEV;
> > +		}  
> 
> If there is no PCI device KNI should still work.

Right now it is possible to use KNI with netvsc PMD on Hyper-V/Azure.
With this patch that won't be possible.