Re: [libvirt] Add support for vhost-user-scsi-pci/vhost-user-blk-pci
FYI there's some more recent discussion over here: https://www.redhat.com/archives/libvir-list/2019-December/msg00817.html There isn't any objections to using for vhost-user-blk, so maybe that's a good place to start. Thanks, Cole On 10/15/19 7:34 AM, Li Feng wrote: > Cole Robinson 于2019年10月15日周二 上午1:48写道： >> >> On 10/14/19 3:12 AM, Li Feng wrote: >>> Hi Cole & Michal, >>> >>> I'm sorry for my late response, I just end my journey today. >>> Thank your response, your suggestion is very helpful to me. >>> >>> I have added Michal in this mail, Michal helps me review my initial >>> patchset. >>> (https://www.spinics.net/linux/fedora/libvir/msg191339.html) >>> >> >> Whoops I missed that posting, I didn't realize you had sent patches! >> >>> All concern about this feature is the XML design. >>> My original XML design exposes more details of Qemu. >>> >>> >>> >>> >>> >>> >>> >>> >>> As Cole's suggestion, the better design with all vhost-user-scsi/blk >>> features would like this: >>> >>> vhost-user-blk: >>> >>> >>> >>> >>> >>> >>> >>> >> function='0x0'/> >>> >>> >>> vhost-user-scsi: >>> >>> >>> >>> >>> >>> >>> >>> >>> >> >> I think my SCSI idea is wrong, sorry. vhost-user-scsi is for passing a >> scsi host adapter to the VM, correct? If so, then it's not really a >> , and so using the existing vhost-scsi support in is >> probably better. could possible be used for vhost-user-blk as well >> >> Can you provide some examples of full qemu command lines using >> vhost-user-blk and vhost-user-scsi? Just linking to examples else where >> is fine, but I'm wondering if there's more context > > You could check the vhost-user-scsi/blk examples from SPDK pages: > https://spdk.io/doc/vhost.html > >> >> Internally we already have an abstraction for vhost-scsi: >> >> >> >> >> >> >> The obvious extension would be >> >> >> > path='/path/to/vhost-user-scsi.sock' mode='client'/> >> >> >> Internally implementing this will be weird. The parameters are >> only dictated by the hostdev type= field, but in this case they would be >> dictated by the field, and we would want to reuse the >> internal chardev abstraction. >> >> vhost-user-blk could be implemented similarly, but with type='storage' >> which is the way we pass through block devices to LXC guests, but it >> isn't currently supported in the qemu driver. >> >> I dunno. Maybe Michal or danpb can provide guidance >> > @Michal, @danpb, could you give some guidance? >> >>> Conclusion: >>> 1. Add new type(vhostuser) for disk label; >>> 2. Add queue sub-label for disk to support multiqueue(>> num='4'/>) or reusing the driver label >>> (>> Qemu support multiqueue like this: >>> -device vhost-user-scsi-pci,id=scsi0,chardev=spdk_vhost_scsi0,num_queues=4 >>> -device vhost-user-blk-pci,chardev=spdk_vhost_blk0,num-queues=4 >>> >> >> num-queues is already supported by libvirt for both and >> with , so whether we use or you won't >> need to add any new XML here. > Got it. > >> >>> Another question: >>> When qemu is connecting to a vhost-user-scsi controller[1], there may >>> exist multiple LUNs under one target, >>> then one disklabel() will represent multiple SCSI LUNs, >>> the 'dev' property() will be ignored, right? >>> In other words, for vhost-user-scsi disk, it more likes a controller, >>> maybe the controller label is suitable. >>> >> >> Yes you are right, and this was my understanding. But then its not >> really a in libvirt's sense because we can't attach >> emulated devices to it, so it's more a fit for the existing >> vhost-user support. Unfortunately it's not really a clean fit anywhere, >> there will have to be some kind of compromise. And I'm not sure if >> or is right for vhost-user-blk, but hopefully others >> have more clear opinions. > > I'm also confused about it. > Thanks for your reply. > > Thanks, > Feng Li > >> >> Thanks, >> Cole >> >>> I look forward to he
Re: [libvirt] Add support for vhost-user-scsi-pci/vhost-user-blk-pci
On 10/14/19 3:12 AM, Li Feng wrote: > Hi Cole & Michal, > > I'm sorry for my late response, I just end my journey today. > Thank your response, your suggestion is very helpful to me. > > I have added Michal in this mail, Michal helps me review my initial patchset. > (https://www.spinics.net/linux/fedora/libvir/msg191339.html) > Whoops I missed that posting, I didn't realize you had sent patches! > All concern about this feature is the XML design. > My original XML design exposes more details of Qemu. > > > > > > > > > As Cole's suggestion, the better design with all vhost-user-scsi/blk > features would like this: > > vhost-user-blk: > > > > > > > > function='0x0'/> > > > vhost-user-scsi: > > > > > > > > > I think my SCSI idea is wrong, sorry. vhost-user-scsi is for passing a scsi host adapter to the VM, correct? If so, then it's not really a , and so using the existing vhost-scsi support in is probably better. could possible be used for vhost-user-blk as well Can you provide some examples of full qemu command lines using vhost-user-blk and vhost-user-scsi? Just linking to examples else where is fine, but I'm wondering if there's more context Internally we already have an abstraction for vhost-scsi: The obvious extension would be Internally implementing this will be weird. The parameters are only dictated by the hostdev type= field, but in this case they would be dictated by the field, and we would want to reuse the internal chardev abstraction. vhost-user-blk could be implemented similarly, but with type='storage' which is the way we pass through block devices to LXC guests, but it isn't currently supported in the qemu driver. I dunno. Maybe Michal or danpb can provide guidance > Conclusion: > 1. Add new type(vhostuser) for disk label; > 2. Add queue sub-label for disk to support multiqueue( num='4'/>) or reusing the driver label > ( Qemu support multiqueue like this: > -device vhost-user-scsi-pci,id=scsi0,chardev=spdk_vhost_scsi0,num_queues=4 > -device vhost-user-blk-pci,chardev=spdk_vhost_blk0,num-queues=4 > num-queues is already supported by libvirt for both and with , so whether we use or you won't need to add any new XML here. > Another question: > When qemu is connecting to a vhost-user-scsi controller[1], there may > exist multiple LUNs under one target, > then one disklabel() will represent multiple SCSI LUNs, > the 'dev' property() will be ignored, right? > In other words, for vhost-user-scsi disk, it more likes a controller, > maybe the controller label is suitable. > Yes you are right, and this was my understanding. But then its not really a in libvirt's sense because we can't attach emulated devices to it, so it's more a fit for the existing vhost-user support. Unfortunately it's not really a clean fit anywhere, there will have to be some kind of compromise. And I'm not sure if or is right for vhost-user-blk, but hopefully others have more clear opinions. Thanks, Cole > I look forward to hearing from you as soon as possible. > > [1]: https://spdk.io/doc/vhost.html > > Feng Li > > Cole Robinson 于2019年10月10日周四 上午6:48写道： >> >> Sorry for the late reply, and thanks Jano for pointing out elsewhere >> that this didn't receive a response. >> >> On 8/12/19 5:56 AM, Li Feng wrote: >>> Hi Guys, >>> >>> And I want to add the vhost-user-scsi-pci/vhost-user-blk-pci support >>> for libvirt. >>> >>> The usage in qemu like this: >>> >>> Vhost-SCSI >>> -chardev socket,id=char0,path=/var/tmp/vhost.0 >>> -device vhost-user-scsi-pci,id=scsi0,chardev=char0 >>> Vhost-BLK >>> -chardev socket,id=char1,path=/var/tmp/vhost.1 >>> -device vhost-user-blk-pci,id=blk0,chardev=char1 >>> >> >> Indeed that matches what I see for the qemu commits too: >> >> https://git.qemu.org/?p=qemu.git;a=commit;h=00343e4b54b >> https://git.qemu.org/?p=qemu.git;a=commit;h=f12c1ebddf7 >> >>> What type should I add for libvirt. >>> Type1: >>> >>> >> path='/tmp/vhost-scsi.sock'> >>> >>> >>> >>> >>> Type2: >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>
Re: [libvirt] Add support for vhost-user-scsi-pci/vhost-user-blk-pci
Sorry for the late reply, and thanks Jano for pointing out elsewhere that this didn't receive a response. On 8/12/19 5:56 AM, Li Feng wrote: Hi Guys, And I want to add the vhost-user-scsi-pci/vhost-user-blk-pci support for libvirt. The usage in qemu like this: Vhost-SCSI -chardev socket,id=char0,path=/var/tmp/vhost.0 -device vhost-user-scsi-pci,id=scsi0,chardev=char0 Vhost-BLK -chardev socket,id=char1,path=/var/tmp/vhost.1 -device vhost-user-blk-pci,id=blk0,chardev=char1 Indeed that matches what I see for the qemu commits too: https://git.qemu.org/?p=qemu.git;a=commit;h=00343e4b54b https://git.qemu.org/?p=qemu.git;a=commit;h=f12c1ebddf7 What type should I add for libvirt. Type1: Type2: I think wiring this into makes more sense. is really an abstraction for assigning a (typically) physical host device to the VM, so it handles things like hiding a PCI device from the host, and passing that exact device to the VM. In the vhost-user-scsi/blk case, the host device is just a special process running on the other side of a socket, and the device represented to the guest is a typical virtio device. So to me it makes more sense as a with a that points at that socket. target bus=virtio vs bus=scsi is already used to distinguish between virtio-blk and virtio-scsi, so I think we can keep that bit as is, with the to match. We just need to differentiate between plain virtio and vhost-user network devices already have vhostuser support: Internally that is a virDomainChrSourceDefPtr which is our internal representation of a chardev. So I think something akin to this is the way to go. It will likely require updating a LOT of places in the code that check disk type= field, probably most places that care about whether type=NETWORK or type=!NETWORK will need to be mirrored for the new type. - Cole -- libvir-list mailing list libvir-list@redhat.com https://www.redhat.com/mailman/listinfo/libvir-list
[libvirt] Add support for vhost-user-scsi-pci/vhost-user-blk-pci
Hi Guys, And I want to add the vhost-user-scsi-pci/vhost-user-blk-pci support for libvirt. The usage in qemu like this: Vhost-SCSI -chardev socket,id=char0,path=/var/tmp/vhost.0 -device vhost-user-scsi-pci,id=scsi0,chardev=char0 Vhost-BLK -chardev socket,id=char1,path=/var/tmp/vhost.1 -device vhost-user-blk-pci,id=blk0,chardev=char1 What type should I add for libvirt. Type1: Type2: Could anyone give some suggestions? Thanks, Feng Li -- The SmartX email address is only for business purpose. Any sent message that is not related to the business is not authorized or permitted by SmartX. 本邮箱为北京志凌海纳科技有限公司（SmartX）工作邮箱. 如本邮箱发出的邮件与工作无关,该邮件未得到本公司任何的明示或默示的授权. -- libvir-list mailing list libvir-list@redhat.com https://www.redhat.com/mailman/listinfo/libvir-list
