Re: [Xen-devel] [BUG] After upgrade to Xen 4.12.0 iommu=no-igfx

From: Andrew Cooper <andrew.cooper3@citrix.com>
To: Roman Shaposhnik <roman@zededa.com>
Cc: "jgross@suse.com" <jgross@suse.com>,
	"Paul Durrant" <Paul.Durrant@citrix.com>,
	"jbeulich@suse.com" <jbeulich@suse.com>,
	"xen-devel@lists.xenproject.org" <xen-devel@lists.xenproject.org>,
	"boris.ostrovsky@oracle.com" <boris.ostrovsky@oracle.com>,
	"Roger Pau Monné" <roger.pau@citrix.com>
Subject: Re: [Xen-devel] [BUG] After upgrade to Xen 4.12.0 iommu=no-igfx
Date: Tue, 23 Jul 2019 19:12:54 +0100	[thread overview]
Message-ID: <81416abc-e5f5-76de-a34a-87412e125e64@citrix.com> (raw)
In-Reply-To: <CAMmSBy_Jh_NHTn_VYkNL8FxcnfMkpiq94E+XqNK9wJWm7tH0pw@mail.gmail.com>

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On 23/07/2019 18:58, Roman Shaposhnik wrote:
> On Tue, Jul 23, 2019 at 10:50 AM Andrew Cooper
> <andrew.cooper3@citrix.com> wrote:
>> On 23/07/2019 18:48, Roman Shaposhnik wrote:
>>> On Tue, Jul 23, 2019 at 10:35 AM Andrew Cooper
>>> <andrew.cooper3@citrix.com> wrote:
>>>> On 23/07/2019 18:32, Roman Shaposhnik wrote:
>>>>> Hi Roger!
>>>>>
>>>>> I applied your patch, removed no-igfx and I still see the original
>>>>> problem. Please let me know what other logs/debugs would you need at
>>>>> this point.
>>>> Please can you collect a full boot log with iommu=debug
>>> How long of an output should I expect when iommu=debug is enabled?
>>> I've just enabled it and I'm looking at what appears to be an endless
>>> scroll of debug info.
>>>
>>> This is all I see for the good 5 minutes at this point. Culminating with:
>>> (XEN)   (XEN) APIC error on CPU0: 40(00)
>>>
>>> and a failure to boot.
>>>
>>> Note that this is still without no-igfx
>>>
>>> I'm attaching the tail end of this log.
>> Sadly, what is useful is the head of the log, before it starts
>> complaining loudly about every DMA fault.
> No worries. Take a look at the head of the log attached.
>
> Btw, I'm kind of curious why iommu=debug would actually make it crash

The system is rather sickly, and is debugging at a rate slower than
incoming faults, which is going to starve whichever CPU is taking the
IOMMU interrupt.

I wouldn't worry about the APIC error now.

Curiously, there is one single intremap error on boot, which is likely
unrelated.

(XEN) [VT-D]INTR-REMAP: Request device [0000:f0:1f.0] fault index 0, iommu reg = ffff82c0008e0000

(XEN) [VT-D]INTR-REMAP: reason 22 - Present field in the IRTE entry is clear

This will be irq0 from the IO-APIC.

Can you try booting following the guidance from

(XEN) [VT-D]found ACPI_DMAR_RMRR:

(XEN) [VT-D]  RMRR address range 8d800000..8fffffff not in reserved memory; need "iommu_inclusive_mapping=1"?

(XEN) [VT-D] endpoint: 0000:00:02.0

which I noted on my first reply?  Given that Rogers patch didn't help,
something else is going on.

~Andrew

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