[pve-devel] issues with Virtio-SCSI devicde on Proxmox...

[Fiona Ebner]

Hi,

Am 12.08.24 um 12:40 schrieb Christian Moser:
> Hello,
> 
> I work for VSI (VMS Software Inc) which is porting the OpenVMS operating system to x86. At this point we successfully on various
> hypervisors, but have some issues on the KVM running on Proxmox.
> 
> The OpenVMS VM works just fine with SATA disks and it also works with for example virtio-network device etc., but trying to use
> virtio-scsi hangs  the driver. I have debugged this and I can successfully configure the port/controller, send the IO request to the
> device. It then gets processed by the device, which posts the results and sets the interrupt bit in the ISR register, but it never
> asserts the interrupt hence the driver never gets notified and the I/O hangs.
> 
> I have tried both “virtio-scsi-pci” and “virtio-scsi-single”, but no luck. The emulated virtio-scsi device is a legacy device. But
> then again, the virtio-network device is also a legacy device and here we are getting interrupts. One thing which bothers me is the
> fact that the “legacy interrupt disable” bit is set in the PCI config space of the virtio-scsi device (i.e. bit 10 at offset 4)
> 
> Questions:
> *	is there a way to configure a modern virtio-scsi devcie (i.e. disable_legacy=on) ?

I've already answered this question when you asked in a mail addressed
directly to me:

Am 12.08.24 um 11:58 schrieb Fiona Ebner:
> Hi,
> 
> It seems that you either need to attach the "virtio-scsi-pci" device to
> a pcie bus or explicitly set the "disable_legacy=on" option for the
> device, neither of which Proxmox VE currently does or allows
> configuring. The only way right now seems to be to attach the disk
> yourself via custom arguments (the 'args' in the Proxmox VE VM
> configuration), but then the disk will be invisible to Proxmox VE
> operations which look at specific disk keys in the configuration!
> 
> Feel free to open a feature request on our bug tracker to make this
> configurable: https://bugzilla.proxmox.com/
> 
> P.S. Please write to the developer list rather than individual
> developers for such questions in the feature:
> https://lists.proxmox.com/cgi-bin/mailman/listinfo/pve-devel
> 
> Best Regards,
> Fiona

> *	why is the legacy interrupt bit set in the PCI config space ?

Most likely because the virtio-scsi-pci is configured without the
"disable_legacy=on" option. If not explicitly set, the option will be
"disable_legacy=auto" and when not attached to PCIe (which is the case
for Proxmox VE currently), then legacy mode will be enabled.

> *	Are there any working driver for virtio-scsi on this KVM using Q35 machine? i.e. any other OS

The virtio drivers for Windows and the ones in Linux work just fine with
our configuration.


> Any thoughts why these interrupts are not getting delivered on the PCIE bus?

We do not configure the virtio-scsi-pci on a PCIe bus currently, see my
initial answer.

Best Regards,
Fiona