Re: [PATCH 15/16] xen/vtd: prevent from assign the device with shared rmrr

["Chen, Tiejun" <tiejun.chen@intel.com>]

On 9/6/2015 11:19 AM, Tamas K Lengyel wrote:
>>
>> diff --git a/xen/drivers/passthrough/vtd/iommu.c
>> b/xen/drivers/passthrough/vtd/iommu.c
>> index 836aed5..038776a 100644
>> --- a/xen/drivers/passthrough/vtd/iommu.c
>> +++ b/xen/drivers/passthrough/vtd/iommu.c
>> @@ -2310,12 +2310,16 @@ static int intel_iommu_assign_device(
>>               PCI_DEVFN2(bdf) == devfn &&
>>               rmrr->scope.devices_cnt > 1 )
>>          {
>> +            u32 relaxed = flag & XEN_DOMCTL_DEV_RDM_RELAXED;
>> +
>>              printk(XENLOG_G_ERR VTDPREFIX
>> -                   " cannot assign %04x:%02x:%02x.%u"
>> +                   " Currently its %s to assign %04x:%02x:%02x.%u"
>>                     " with shared RMRR at %"PRIx64" for Dom%d.\n",
>> +                   relaxed ? "disallowed" : "risky",
>>
>
> This debug message is backwards?

Yeah. Its indeed like this, relaxed ? "risky" : "disallowed"

But lets wait Jan's comment to step next.

>
>
>>                     seg, bus, PCI_SLOT(devfn), PCI_FUNC(devfn),
>>                     rmrr->base_address, d->domain_id);
>> -            return -EPERM;
>> +            if ( !relaxed )
>> +                return -EPERM;
>>          }
>>      }
>>
>>
>> Tamas, do you actually mean to assign these to _different_
>>>> guests, considering the log fragment above?)
>>>>
>>>>
>>> No, I actually want to assign them to the same domain. The domain creation
>>> fails with either of those devices specified for passthrough whether they
>>> are to be attached to the same domain or not.
>>>
>>>
>> Tamas, could you try this in your case?
>>
>
> Took me a while to find the xl config option to set this flag (pci = [
> 'sbdf, rdm_policy=strict/relaxed' ]) but now it works as expected!
>

I remember 'relaxed' is a default value so 'rdm_policy' can't be dropped 
here if you like this.

Thanks
Tiejun