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

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

Sorry for this delay response because I was on vacation.

On 9/5/2015 5:52 AM, Tamas K Lengyel wrote:
> On Fri, Sep 4, 2015 at 2:17 AM, Jan Beulich <JBeulich@suse.com> wrote:
>
>> >>> On 03.09.15 at 21:39, <tamas.k.lengyel@gmail.com> wrote:
>> > So this change in 4.6 prevents me from passing through devices that have
>> > worked previously with VT-d:
>> >
>> > (XEN) [VT-D] cannot assign 0000:00:1a.0 with shared RMRR at ae8a9000 for
>> > Dom30.
>> > (XEN) [VT-D] cannot assign 0000:00:1d.0 with shared RMRR at ae8a9000 for
>> > Dom31.
>> >
>> > The devices are the USB 2.0 devices on a DQ67SW motherboard:
>> >
>> > 00:1a.0 USB controller: Intel Corporation 6 Series/C200 Series Chipset
>> > Family USB Enhanced Host Controller #2 (rev 04)
>> > 00:1d.0 USB controller: Intel Corporation 6 Series/C200 Series Chipset
>> > Family USB Enhanced Host Controller #1 (rev 04)
>>
>> Please don't top post. And I'm also puzzled by you sending this to
>> Ian rather than the author.
>>
>
> Hm, I've just hit reply-all to the latest message I've found in the thread.
>
>
>>
>> Technically - Tiejun, should this perhaps be permitted in relaxed
>> mode, at least until group assignment gets implemented? (Or

I agree. What about this?

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",
                     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?

Thanks
Tiejun