[libvirt] [PATCH] qemu: support bootindex on vfio-ccw mdev device

[Boris Fiuczynski]

On 8/2/19 3:30 PM, Peter Krempa wrote:
> On Fri, Aug 02, 2019 at 15:15:59 +0200, Boris Fiuczynski wrote:
>> Add support to specify a boot order on vfio-ccw passthrough devices.
>>
>> Signed-off-by: Boris Fiuczynski <fiuczy at linux.ibm.com>
>> Acked-by: Jason J. Herne <jjherne at linux.ibm.com>
>> Reviewed-by: Marc Hartmayer <mhartmay at linux.ibm.com>
>> ---
>>   src/qemu/qemu_command.c                       | 27 +++++++++++++----
>>   .../hostdev-subsys-mdev-vfio-ccw-boot.args    | 29 +++++++++++++++++++
>>   .../hostdev-subsys-mdev-vfio-ccw-boot.xml     | 23 +++++++++++++++
>>   tests/qemuxml2argvtest.c                      |  4 +++
>>   4 files changed, 78 insertions(+), 5 deletions(-)
>>   create mode 100644 tests/qemuxml2argvdata/hostdev-subsys-mdev-vfio-ccw-boot.args
>>   create mode 100644 tests/qemuxml2argvdata/hostdev-subsys-mdev-vfio-ccw-boot.xml
> 
> Note that I don't currently have enough information to verify that the
> mdev claim is correct (e.g. why it's only with CCW devices?), but I have
> two formal comments:
Since I know that on s390 you can boot from a vfio-ccw mediated device 
but not from a vfio-ap mediated device I chose the default as "not 
capable to boot from" and check especially for the "known to be capable 
to boot from" mdevs. I have no problem changing the logic if desired.

If we want to skip the checking than an qemu internal error like this 
occurs:
error: Failed to start domain mini-ap
error: internal error: qemu unexpectedly closed the monitor: 
2019-08-05T13:44:27.871697Z qemu-system-s390x: -device 
vfio-ap,id=hostdev0,sysfsdev=/sys/bus/mdev/devices/9063cba3-ecef-47b6-abcf-3fef4fdcad85,bootindex=1: 
Property '.bootindex' not found

> 
>>
>> diff --git a/src/qemu/qemu_command.c b/src/qemu/qemu_command.c
>> index fee51158a9..36138e2ccf 100644
>> --- a/src/qemu/qemu_command.c
>> +++ b/src/qemu/qemu_command.c
>> @@ -5613,6 +5613,9 @@ qemuBuildHostdevMediatedDevStr(const virDomainDef *def,
>>       if (qemuBuildDeviceAddressStr(&buf, def, dev->info, qemuCaps) < 0)
>>           goto cleanup;
>>   
>> +    if (dev->info->bootIndex)
>> +        virBufferAsprintf(&buf, ",bootindex=%u", dev->info->bootIndex);
>> +
>>       if (virBufferCheckError(&buf) < 0)
>>           goto cleanup;
>>   
>> @@ -5624,6 +5627,22 @@ qemuBuildHostdevMediatedDevStr(const virDomainDef *def,
>>       return ret;
>>   }
>>   
>> +static bool
>> +qemuHostdevSupportsBoot(virDomainHostdevDefPtr hostdev)
> 
> Refactor to this function should be separate from the logic change
> below.

Agreed.

> 
>> +{
>> +    if (hostdev->mode == VIR_DOMAIN_HOSTDEV_MODE_SUBSYS) {
>> +        virDomainHostdevSubsysPtr subsys = &hostdev->source.subsys;
>> +        if (subsys->type == VIR_DOMAIN_HOSTDEV_SUBSYS_TYPE_PCI ||
>> +            subsys->type == VIR_DOMAIN_HOSTDEV_SUBSYS_TYPE_USB ||
>> +            subsys->type == VIR_DOMAIN_HOSTDEV_SUBSYS_TYPE_SCSI ||
>> +            (subsys->type == VIR_DOMAIN_HOSTDEV_SUBSYS_TYPE_MDEV &&
>> +            subsys->u.mdev.model == VIR_MDEV_MODEL_TYPE_VFIO_CCW)) {
> 
> This line is misaligned. Please make sure that it's clear that the above
> line belongs to the term in the brackets.

I will fix it.

> 
> 
>> +            return true;
>> +        }
>> +    }
>> +    return false;
>> +}
>> +
>>   static int
>>   qemuBuildHostdevCommandLine(virCommandPtr cmd,
>>                               const virDomainDef *def,
>> @@ -5638,13 +5657,11 @@ qemuBuildHostdevCommandLine(virCommandPtr cmd,
>>           char *devstr;
>>   
>>           if (hostdev->info->bootIndex) {
>> -            if (hostdev->mode != VIR_DOMAIN_HOSTDEV_MODE_SUBSYS ||
>> -                (subsys->type != VIR_DOMAIN_HOSTDEV_SUBSYS_TYPE_PCI &&
>> -                 subsys->type != VIR_DOMAIN_HOSTDEV_SUBSYS_TYPE_USB &&
>> -                 subsys->type != VIR_DOMAIN_HOSTDEV_SUBSYS_TYPE_SCSI)) {
>> +            if (!qemuHostdevSupportsBoot(hostdev)) {
>>                   virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
>>                                  _("booting from assigned devices is only "
>> -                                 "supported for PCI, USB and SCSI devices"));
>> +                                 "supported for PCI, USB, SCSI and MDEV "
>> +                                 "of model vfio-ccw devices"));
> 
> Ideally this validation will be done in the validation callback rather
> than in the command line generator. (pre-existing so I don't require you
> to refactor this at this time). >
> Also this error can be probably stashed into qemuHostdevSupportsBoot.
> (and name it like qemuHostdevValidateBoot).

Ok, I will rename the method and move the error report.

> 
> 
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-- 
Mit freundlichen Grüßen/Kind regards
    Boris Fiuczynski

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