From mboxrd@z Thu Jan 1 00:00:00 1970 From: DuanZhenzhong Subject: Re: [PATCH] Bypass mask bit of msix entry in xen Date: Tue, 26 Mar 2013 11:15:29 +0800 Message-ID: <515112D1.6020809@oracle.com> References: <514A80CF.5040705@oracle.com> <514AEB0602000078000C76F6@nat28.tlf.novell.com> <514AE5EE.30402@oracle.com> <514B14D002000078000C7801@nat28.tlf.novell.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; Format="flowed" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <514B14D002000078000C7801@nat28.tlf.novell.com> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: Jan Beulich Cc: Konrad Rzeszutek Wilk , Feng Jin , xen-devel List-Id: xen-devel@lists.xenproject.org Jan Beulich wrote: >>>> On 21.03.13 at 11:50, Zhenzhong Duan wrote: >>>> >> On 2013-03-21 18:12, Jan Beulich wrote: >> >>> Furthermore, without explanation I also don't see how the mask >>> bit is now being dealt with properly: From an abstract pov you'd >>> need to merge ("or") the guest-requested mask bit state with what >>> Xen needs for its own purposes. I don't see anything like that here >>> or in the qemu side patch. >>> >> Right, I didn't consider combine xen's masking with guest's. >> My patch just target making irq affinity in old hvm guest work and >> sometimes no irq handler panic. >> But I would like to know what's the result if guest's mask setting >> doesn't pass to device, >> interrupt loss or something else? I see current implemention didn't >> passthrough mask bit too. >> > > The effect of this is unknown, as it depends on the particular > driver behavior and assumptions. Loss of interrupts, however, > doesn't appear to be problematic here; instead, interrupts > getting delivered when the driver doesn't expect them seems > to be the much bigger problem. > > Jan > > It's hard to merge guest requested mask with xen's. Because xen lack a irq_desc.depth as kernel for nested irq disable and enable. -- Regards zhenzhong -- Oracle Building, No.24 Building, Zhongguancun Software Park Haidian District, Beijing 100193, China