From mboxrd@z Thu Jan 1 00:00:00 1970 From: Marcelo Tosatti Subject: Re: [PATCH 0/4] MSI-X Enabling Date: Tue, 23 Dec 2008 18:19:32 -0200 Message-ID: <20081223201932.GA6783@amt.cnet> References: <1230019973-16833-1-git-send-email-sheng@linux.intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Avi Kivity , kvm@vger.kernel.org To: Sheng Yang Return-path: Received: from mx2.redhat.com ([66.187.237.31]:49093 "EHLO mx2.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751158AbYLWUTm (ORCPT ); Tue, 23 Dec 2008 15:19:42 -0500 Content-Disposition: inline In-Reply-To: <1230019973-16833-1-git-send-email-sheng@linux.intel.com> Sender: kvm-owner@vger.kernel.org List-ID: On Tue, Dec 23, 2008 at 04:12:49PM +0800, Sheng Yang wrote: > Hi Avi > > This patchset would enable MSI-X support. > > The main change is a new kind of fake device - intercepted MMIO device is > added for supporting to intercept one page contained MSI-X entries table. > > I also consider of doing this intercept in userspace. But I think it's would > be more complex to push it in userspace, for we also have to prevent KVM from > creating page table for the page. Unmapping the page in userspace (with munmap) from the PCI MMIO map will disallow KVM from creating pagetable for the page. > And in the future, we would add hook > function in the read/write operation to enabling mask bit for each MSI-X > entry, may be with pending bits. Can you explain it in more detail? Can't do it from userspace? Are there performance considerations to access in this page? > So I decided to put it in the kernel. > > Another thing is I am not very confident about modify the position of handling > guest memory and MMIO in emulate read/write function. Is it would cause any > side affect? Should not be necessary if done in userspace.