[PATCH v2 08/15] qemu_validate: Check if QEMU's capable of setting iothread pool size

[Michal Prívozník]

On 6/7/22 16:59, Peter Krempa wrote:
> On Tue, Jun 07, 2022 at 14:52:52 +0200, Michal Privoznik wrote:
>> Now that we have a capability that reflects whether QEMU is
>> capable of setting iothread pool size, let's introduce a
>> validator check to make sure users are not trying to use this
>> feature with QEMU that doesn't support it.
>>
>> Signed-off-by: Michal Privoznik <mprivozn at redhat.com>
>> Reviewed-by: Peter Krempa <pkrempa at redhat.com>
>> ---
>>  src/qemu/qemu_validate.c | 24 ++++++++++++++++++++++++
>>  1 file changed, 24 insertions(+)
>>
>> diff --git a/src/qemu/qemu_validate.c b/src/qemu/qemu_validate.c
>> index 9b6245e6d7..7d11ae2c92 100644
>> --- a/src/qemu/qemu_validate.c
>> +++ b/src/qemu/qemu_validate.c
>> @@ -384,6 +384,27 @@ qemuValidateDomainDefCpu(virQEMUDriver *driver,
>>  }
>>  
>>  
>> +static int
>> +qemuValidateDomainDefIOThreads(const virDomainDef *def,
>> +                               virQEMUCaps *qemuCaps)
>> +{
>> +    size_t i;
>> +
>> +    for (i = 0; i < def->niothreadids; i++) {
>> +        virDomainIOThreadIDDef *iothread = def->iothreadids[i];
>> +
>> +        if ((iothread->thread_pool_min != -1 || iothread->thread_pool_max != -1) &&
>> +            !virQEMUCapsGet(qemuCaps, QEMU_CAPS_IOTHREAD_THREAD_POOL_MAX)) {
>> +            virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
>> +                           _("thread_pool_min and thread_pool_max is not supported by this QEMU binary"));
>> +            return -1;
>> +        }
> 
> You'll also need a check that 'thread_pool_max', if supplied, must be
> more or equal to 'thread_pool_min', otherwise:
> 
>  $ virsh dumpxml cd | grep thread_pool
>      <iothread id='3' thread_pool_min='4' thread_pool_max='3'/>
>  $ virsh start cd
>  error: Failed to start domain 'cd'
>  error: internal error: process exited while connecting to monitor: 2022-06-07T14:58:52.420554Z qemu-system-x86_64: bad thread-pool-min/thread-pool-max values
> 

Ah, good point. But there's nothing QEMU specific about this so let me
put it into hypervisor agnostic validator. Which in turn allows me to
amend this change to the 06/15 patch where parser/formatter is introduced.

Michal