From mboxrd@z Thu Jan  1 00:00:00 1970
From: Andrew Cooper <andrew.cooper3@citrix.com>
Subject: Re: Xen-unstable-staging: Xen BUG at iommu_map.c:455
Date: Wed, 01 Apr 2015 00:38:34 +0100
Message-ID: <551B2FFA.6080001@citrix.com>
References: <1864736142.20150331231153@eikelenboom.it>
Mime-Version: 1.0
Content-Type: text/plain; charset="us-ascii"
Content-Transfer-Encoding: 7bit
Return-path: <xen-devel-bounces@lists.xen.org>
Received: from mail6.bemta3.messagelabs.com ([195.245.230.39])
	by lists.xen.org with esmtp (Exim 4.72)
	(envelope-from <amc96@hermes.cam.ac.uk>) id 1Yd5jw-0004xs-9l
	for xen-devel@lists.xenproject.org; Tue, 31 Mar 2015 23:38:36 +0000
In-Reply-To: <1864736142.20150331231153@eikelenboom.it>
List-Unsubscribe: <http://lists.xen.org/cgi-bin/mailman/options/xen-devel>,
	<mailto:xen-devel-request@lists.xen.org?subject=unsubscribe>
List-Post: <mailto:xen-devel@lists.xen.org>
List-Help: <mailto:xen-devel-request@lists.xen.org?subject=help>
List-Subscribe: <http://lists.xen.org/cgi-bin/mailman/listinfo/xen-devel>,
	<mailto:xen-devel-request@lists.xen.org?subject=subscribe>
Sender: xen-devel-bounces@lists.xen.org
Errors-To: xen-devel-bounces@lists.xen.org
To: Sander Eikelenboom <linux@eikelenboom.it>, Jan Beulich <jbeulich@suse.com>
Cc: xen-devel <xen-devel@lists.xenproject.org>
List-Id: xen-devel@lists.xenproject.org

On 31/03/2015 22:11, Sander Eikelenboom wrote:
> Hi all,
>
> I just tested xen-unstable staging (changeset: git:0522407-dirty) 
>
> with revert of commit 1aeb1156fa43fe2cd2b5003995b20466cd19a622
> (due to an already reported but not yet resolved issue)
>
> and build with qemu xen from git://xenbits.xen.org/staging/qemu-upstream-unstable.git
> (to include the pci command register patch from Jan)
>
>
> and now came across this new splat when starting an HVM with PCI passtrhough:

Wow - you are getting all the fun bugs at the moment!

Nothing has changed in the AMD IOMMU driver for a while, but the
BUG_ON() is particularly unhelpful at identifying what went wrong.

As a first pass triage, can you rerun with

diff --git a/xen/drivers/passthrough/amd/iommu_map.c
b/xen/drivers/passthrough/amd/iommu_map.c
index 495ff5c..f15c324 100644
--- a/xen/drivers/passthrough/amd/iommu_map.c
+++ b/xen/drivers/passthrough/amd/iommu_map.c
@@ -451,8 +451,9 @@ static int iommu_pde_from_gfn(struct domain *d,
unsigned long pfn,
     table = hd->arch.root_table;
     level = hd->arch.paging_mode;

-    BUG_ON( table == NULL || level < IOMMU_PAGING_MODE_LEVEL_1 ||
-            level > IOMMU_PAGING_MODE_LEVEL_6 );
+    BUG_ON(table == NULL);
+    BUG_ON(level < IOMMU_PAGING_MODE_LEVEL_1);
+    BUG_ON(level > IOMMU_PAGING_MODE_LEVEL_6);

     next_table_mfn = page_to_mfn(table);

which will help identify which of the conditions is failing.

Can you please also provide the full serial log, including iommu=debug?

~Andrew