SR-IOV support in Xen. Yaozu (Eddie) Dong Yunhong Jiang Kun (Kevin) Tian

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1 SR-IOV support in Xen Yaozu (Eddie) Dong Yunhong Jiang Kun (Kevin) Tian

2 Agenda SR-IOV specification overview Xen/SR-IOV architecture Discussions 2

3 SR-IOV specification overview Start with a single function device HW under the control of privileged SW Includes an SR-IOV Extended Capability Physical Function (PF) IOVM DD VM 0 DD VM 1 DD Replicate the resources needed by a VM MMIO for direct communication RID to tag DMA traffic Minimal configuration space Virtual Function (VF) Introduces PCI Manager (PCIM) Conceptual SW entity Completes the configuration model Translates VF into a full function Configures SR-IOV resources Physical Function Virtual Function PF VF Shared Resource VF PCIM DMA, PIO, and Interrupts Initialization and Configuration 3

4 Xen/SRIOV architecture Dom0 (Service VM) user SR-IOV generic VF CFGS emulation Guest App CP DM SR-IOV VF management Network configuration Normal PCI driver with hot add/removal support Dom0 kernel Xen PF driver CFGS access Alt1: Inter-VM communication Guest Kernel Alt2: PIO/MMIO based virtual mailbox/doorbell VF driver HW Alt3: HW mailbox/doorbell 4

5 Control Panel VF management: A generic tool with notification to PF for state change VFnums setting / Show Enable/Disable/Migrate VFs Network configuration Can Ethtool service for this? Or a totally new tool? 5

6 SR-IOV VF/PF Communication Channel Inter-VM APIs VMM cooperative VF driver VF driver will depends on VMM, Guest OS, and even release from VMM vendor Primitive hypercalls are not sufficient There is no Windows based Xen Inter-VM high level APIs in upstream Xen vendors may release their own abstract APIs with separately Guest hardware VMM independent VF driver Real Hardware mailbox/doorbell No SR-PCIM involvement Good Performance, but IHVs may not implement Virtual mailbox/doorbell Need SR-PCIM support Need SR-IOV standard VF/PF driver pair s decision to use whatever mechanism, but suggest using guest hardware 6

7 Virtual hardware for PF/VF communication Dom0 (Service VM) user DM VF->PF doorbell can use I/O PF->VF doorbell uses virtual IRQ 4: Emulation SRIOV 3: Back to DM Dom0 kernel 5: Notification 6: Ack PF driver 7: Done 8: Done VF driver Guest Kernel 1: Guest write I/O Xen 2: VM Exit to hypervisor 7

8 PCI Device Instance of VF in Host? No create VF instance Need access path for Qemu to R/W VF CFGS Modifications are mostly in Qemu side Start from this for TTM Created VF instance Pros: Easy for assignment Cons: Confuse to other pci modules, invasive change, need community decision on how to change Long term solution 8

9 Summary IOMMU based SR-IOV support is an ideal IO virtualization Each guest can get a portion of hardware VMM doesn t need to intercept at runtime High throughput, Low CPU utilization, Perfect scalability Early VMM support for SR-IOV is critical to IHVs to implement PF/VF drivers Dom0 Linux version also matters in terms of PF driver development 9

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Enhancing pass through device support with IOMMU. Haitao Shan Yunhong Jiang Allen M Kay Eddie (Yaozu) Dong

Enhancing pass through device support with IOMMU Haitao Shan (haitao.shan@intel.com) Yunhong Jiang Allen M Kay Eddie (Yaozu) Dong Agenda Current Status Further enhancement Hardening host Improving functionality