Hi all, I just asked the same question in vfio-users mailing list.
Ref link: https://www.redhat.com/archives/vfio-users/2016-September/msg00097.html I got response like "The vfio can't help in our use case. A new framework called "mediated device" can help to achieve this. After a few hours of googling on mediated devices I landed here for an discussion. I think this is the right mailing list to ask this. Question: _______________________ _______________________ | | | | | Virtual Machine 1 | | Virtual Machine 2 | | ___________ | | ___________ | | | | | | | | | | | VM1 Memory| | | |VM2 Memory | | | |___________| | | |___________| | | ^ | | ^ | |____________ | ________| |________ | ____________| | | | | ________V________________________________V___________ | | | | | | IOMMU | | |_______|_____________________ ___________|___________| ^ ^ | | [To/From VM1 Buffers] [To/From VM2 Buffers] HOST ----------------|------------- -------------------|------------------------ _________ | ______________________________ |_____________ PCI Device | | PCI NIC CARD | | | | (Single PCI Function) | | | __|________________________________|__ | | | | | | | | | | PCIe DMA | | | | |_ |_______________________________ |__| | | | | | | V V | | Queue for VM1 Queues for VM2 | | |RX|TX| |RX|TX| | | |RX|TX| |RX|TX| | | |RX|TX| |RX|TX| | | ^ ^ | | | ___________________ | | | | | | | | | ------>| Queue Classifier |<---- | | |___________________| | | | | | | | MAC | | | |___________________| ------ | |_____________________________ _____________|Port|_________| ------ || || ||___ |___----> To Network Fabric We are trying to share the PCIe NIC card with multiple VMs. PCI NIC card has one Physical function (NO SRIOV support). The NIC has multiple queues (each with TX and RX descriptor ring). Packets are placed in queue based on packet classifier(Ex: MAC addresses). So each queue can be used for a network interface, therefore host can have multiple virtual network interfaces. We are planning to assign each queue to each VM (emulate like PCI Virual functions, but our HW doesnt support Virtual function). Packet buffer for corresponding queue will reside in VM's memory. DMA in the PCI card need to push/pull packet data to/from directly to the VM's memory (for this we need IOMMU support). We need to eliminate the intermediate CPU memory copy. Is it possible to use mediated device frame work in the above mentioned situation? *Regards,* Sasikumar Natarajan VVDN Technologies Pvt Ltd
