From mboxrd@z Thu Jan 1 00:00:00 1970 From: Konrad Rzeszutek Wilk Subject: Re: MSI message data register configuration in Xen guests Date: Thu, 28 Jun 2012 16:52:03 -0400 Message-ID: <20120628205203.GA25097@phenom.dumpdata.com> References: Mime-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Return-path: Content-Disposition: inline In-Reply-To: List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: Rolu Cc: Deep Debroy , xen-devel@lists.xen.org List-Id: xen-devel@lists.xenproject.org On Tue, Jun 26, 2012 at 04:51:29AM +0200, Rolu wrote: > On Tue, Jun 26, 2012 at 4:38 AM, Deep Debroy wrote: > > Hi, I was playing around with a MSI capable virtual device (so far > > submitted as patches only) in the upstream qemu tree but having > > trouble getting it to work on a Xen hvm guest. The device happens to > > be a QEMU implementation of VMWare's pvscsi controller.=A0The device > > works fine in a Xen guest when I switch the device's=A0code to force > > usage of legacy interrupts with upstream QEMU. With MSI based > > interrupts, the device works fine on a KVM guest but as stated before, > > not on a Xen guest. After digging a bit, it appears, the reason for > > the failure in Xen guests is that the MSI data register in the Xen > > guest ends up with a value of 4300 where the Deliver Mode value of 3 > > happens to be reserved (per spec) and therefore illegal. The > > vmsi_deliver routine in Xen rejects MSI interrupts with such data as > > illegal (per expectation) causing all commands issued by the guest OS > > on the device to timeout. > > > > Given this above scenario, I was wondering if anyone can shed some > > light on how to debug this further for Xen. Something I would > > specifically like to know is where the MSI data register configuration > > actually happens. Is it done by some code specific to Xen and within > > the Xen codebase or it all done within QEMU? > > > = > This seems like the same issue I ran into, though in my case it is > with passed through physical devices. See > http://lists.xen.org/archives/html/xen-devel/2012-06/msg01423.html and > the older messages in that thread for more info on what's going on. No > fix yet but help debugging is very welcome. Huh? You said in http://lists.xen.org/archives/html/xen-devel/2012-06/msg01= 653.html "This worked!"