Open Stack

Ok,

Yes sorry, my bad, I got confused because I was looking in the wrong section.

I believe the right place to look for the pass-through pci devices is under hostdev section

    <hostdev mode='subsystem' type='pci' managed='yes'>
      <driver name='vfio'/>
      <source>
        <address domain='0x0000' bus='0x04' slot='0x00' function='0x0'/>
      </source>
      <alias name='hostdev0'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x05' function='0x0'/>
    </hostdev>

Thank you for your help Mohammed

Manuel

-----Original Message-----
From: Mohammed Naser [mailto:mnaser at vexxhost.com]
Sent: Friday, April 5, 2019 12:13 PM
To: Manuel Sopena Ballesteros
Cc: openstack at lists.openstack.org
Subject: Re: Openstack attaching same pci device to 2 different vms?

On Thu, Apr 4, 2019 at 8:55 PM Manuel Sopena Ballesteros
<manuel.sb at garvan.org.au> wrote:
>
> Dear Openstack community,
>
>
>
> I recently setup pci-passthrough against nvme drives to directly attach the disks to the vm as a block device.
>
>
>
> I created 2 vms on the same physical host and I can see the disks (nvme0n1) on both of them:
>
>
>
> [centos at test-nvme-small ~]$ lsblk
>
> NAME    MAJ:MIN RM  SIZE RO TYPE MOUNTPOINT
>
> vda     253:0    0   10G  0 disk
>
> └─vda1  253:1    0   10G  0 part /
>
> nvme0n1 259:0    0  1.8T  0 disk
>
>
>
> [centos at test-nvme-small-2 ~]$ lsblk
>
> NAME    MAJ:MIN RM  SIZE RO TYPE MOUNTPOINT
>
> vda     253:0    0   10G  0 disk
>
> └─vda1  253:1    0   10G  0 part /
>
> nvme0n1 259:0    0  1.8T  0 disk
>
>
>
> So I wanted to check which nvme device was attached to which vm. I thought one option would be to dump the vm xml file from virsh which can be found below (I am only putting the information between the disks section but happy to attach the hole file if needed):
>
>
>
>
>
> Device/disk configuration for instance-00000094
>
>
>
>     <disk type='file' device='disk'>
>
>       <driver name='qemu' type='qcow2' cache='none'/>
>
>       <source file='/var/lib/nova/instances/fd95cc45-1501-4693-8643-944be2ff4625/disk'/>
>
>       <backingStore type='file' index='1'>
>
>         <format type='raw'/>
>
>         <source file='/var/lib/nova/instances/_base/4cc6eebe175e35178cb81853818a1eb103cea937'/>
>
>         <backingStore/>
>
>       </backingStore>
>
>       <target dev='vda' bus='virtio'/>
>
>       <alias name='virtio-disk0'/>
>
>       <address type='pci' domain='0x0000' bus='0x00' slot='0x04' function='0x0'/>
>
>     </disk>
>
>
>
>
>
>
>
> Device/disk configuration for instance-00000093
>
>
>
>     <disk type='file' device='disk'>
>
>       <driver name='qemu' type='qcow2' cache='none'/>
>
>       <source file='/var/lib/nova/instances/7e6a055c-1b4e-458c-89cd-cb8c1d10e939/disk'/>
>
>       <backingStore type='file' index='1'>
>
>         <format type='raw'/>
>
>         <source file='/var/lib/nova/instances/_base/4cc6eebe175e35178cb81853818a1eb103cea937'/>
>
>         <backingStore/>
>
>       </backingStore>
>
>       <target dev='vda' bus='virtio'/>
>
>       <alias name='virtio-disk0'/>
>
>       <address type='pci' domain='0x0000' bus='0x00' slot='0x04' function='0x0'/>
>
>     </disk>
>
>
>
>
>
> Based on this output and If I am not mistaken I am under the impression that the host pci device attached to both vms is 0000:00:04.0
>
>
>
>
>
> Questions:
>
>
>
> Is there an Openstack way to check which pci devices are attached to which vms instead of having to dump the vm xml file?

I don't think so.  I'm not the best at answering this.

> Am I right assuming that the same disk is attached to both vms? If yes, how can that happen?

That's the root device, that's not the PCI passthrough device

>
>
> Thank you very much
>
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Mohammed Naser — vexxhost
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