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

[DERUMIER, Alexandre]

Hi,

Currently they are no way to add custom options for virtio-devices
command line from vm config, so it should be patched to add support for
openvms os and add special tuning.

for 
example:https://git.proxmox.com/?p=qemu-server.git;a=blob_plain;f=PVE/QemuServer.pm;hb=HEAD
sub print_netdevice_full {
 ....

if ($conf->{ostype} && $conf->{ostype} eq 'openvms') {
    tmpstr .= ",disable_legacy=on";
}


>>I have tried both “virtio-scsi-pci” and “virtio-scsi-single”, but no
>>luck. The emulated virtio-scsi device is a legacy device
>>
>>
>>Questions:
>>*	is there a way to configure a modern virtio-scsi devcie (i.e.
>>disable_legacy=on) ?
>>

Do you mean than currently on proxmox, the default is legacy mode and
and not modern ?  I was pretty sure than qemu was defaulting to modern,

and that you need to use  ",disable-legacy=off,disable-modern=true" to
switch to legacy.

(and AFAIK, proxmox qemu version don't have any patch forcing legacy)

but maybe I'm wrong



maybe it's only enabled by default with pci-express (using q35 machine
model) ?

https://github.com/qemu/qemu/blob/9eb51530c12ae645b91e308d16196c68563ea883/docs/pcie.txt
"Virtio devices plugged into PCI Express ports are PCI Express devices
and
have "1.0" behavior by default without IO support.
In both cases disable-legacy and disable-modern properties can be used
to override the behaviour."


in qemu code I see:

https://github.com/qemu/qemu/blob/9eb51530c12ae645b91e308d16196c68563ea883/hw/core/machine.c#L258
GlobalProperty hw_compat_2_6[] = {
    { "virtio-mmio", "format_transport_address", "off" },
    /* Optional because not all virtio-pci devices support legacy mode
*/
    { "virtio-pci", "disable-modern", "on",  .optional = true },
    { "virtio-pci", "disable-legacy", "off", .optional = true },
};
const size_t hw_compat_2_6_len = G_N_ELEMENTS(hw_compat_2_6);

so I'm really not sure what is the real default


do you have qemu command line of another kvm hypervisor
(ovirt,rhev,...) where it's working correctly ?  Maybe they are
enabling modern bits manually , when a virtio device is supporting it ?



-------- Message initial --------
De: Christian Moser <cmos at maklee.com>
Répondre à: Proxmox VE development discussion <pve-
devel at lists.proxmox.com>
À: pve-devel at lists.proxmox.com
Cc: Christian Moser <cmos at maklee.com>
Objet: [pve-devel] issues with Virtio-SCSI devicde on Proxmox...
Date: 12/08/2024 12:40:10

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) ?
*	why is the legacy interrupt bit set in the PCI config space ?
*	Are there any working driver for virtio-scsi on this KVM using
Q35 machine? i.e. any other OS

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

thanks

/cmos

_______________________________________________________
Christian Moser
Mobile:    +358-40-5022105			
Email:      cmos at maklee.com
URL:       www.maklee.com

_______________________________________________
pve-devel mailing list
pve-devel at lists.proxmox.com
https://antiphishing.vadesecure.com/v4?f=MXNCQ25TYXBra2RFV0VXZHojMIIFPS
zCvkhJApFQpU82zfAhP9K7STA7y-
wx1jAbgWgLhPFHm0qw3LR0qKok0w&i=cVVpR014Sk93Z0c1QzFSMs3n08s7G9NqllHFFNJ9
1W0&k=ThnE&r=VWoxMWNDTTl5UmRwenhPYicvAeXd4xlreb0WEHQKfL1pVhoIeFvTknKKfK
g5BYLZ&s=c0303a1ebcdeef9c5d38eaa27d25b873b9eed7bddb72bc270d5944f93d63bb
ec&u=https%3A%2F%2Flists.proxmox.com%2Fcgi-
bin%2Fmailman%2Flistinfo%2Fpve-devel