On Wed, Feb 15, 2017 at 12:15:02AM -0700, Lin Ma wrote: > Hi all, > > We know that libvirt can create fibre channels vHBA on host > based on npiv, and present the LUNs to guest. > > I'd like to implement a virtual fibre channel HBA for qemu, > I havn't investigate it deeply yet. The idea presents a fc > vHBA in guest, interact with remote fc switch through npiv, > The LUNs will be recognized inside guest. I sent this email > here to see if you are in agreement with this approach and > hope to get some ideas/suggestions. > > The frontend is based on virtio, say virtio-fc-pci; the backend > is based on npiv of physical fc hba on host. > The implementation of this virtual fc hba doesn't support Fc-al, > only supports Fabric. It wrappers scsi data info fc frames, then > forwards them to backend, sounds like scsi over fc. > (maybe I can re-use some of virtio-scsi code/idea to deal with scsi data) > > The minimum invocation may look like: > qemu-system-x86_64 \ > ...... \ > -object fibrechannel-backend,id=fcdev0,host=0000:81:00.0 \ > -device > virtio-fc-pci,id=vfc0,fc_backend=fcdev0,wwpn=1000000000000001,wwnn=1100000000000001 > \ > ...... > > BTW, I have no idea how to make migration works: > How to deal with the BDF during migration? > How to deal with the Fabric ID during migration? > > It's a draft idea, There are lots of related code I need to > investigate, Currently this is all thoughts I have. > > Hello Paolo and Stefan, You are the authors of virtio-scsi, > and had some in-depth discuss about virtio-scsi in 2011 > with Hannes, May I have your ideas/thoughts?
I'm not sure it's necessary for the guest to have FC access. Fam Zheng and Paolo are working on virtio-scsi FC NPIV enhancements. It should make NPIV work better without adding a whole new FC device. https://lkml.org/lkml/2017/1/16/439 The plan is: 1. libvirt listens to udev events on the host so it can add/remove QEMU SCSI LUNs. 2. virtio-scsi is extended to include a WWPN that the guest can see. The guest doesn't do any FC fabric level stuff, it just does virtio-scsi as usual. It supports live migration by swapping between a pair of WWPNs across migration. What are the benefits of having FC access from the guest? Stefan
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