From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from aserp1040.oracle.com ([141.146.126.69]:17030 "EHLO aserp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754315AbaHODvg (ORCPT ); Thu, 14 Aug 2014 23:51:36 -0400 Date: Thu, 14 Aug 2014 23:51:22 -0400 From: Konrad Rzeszutek Wilk To: Yijing Wang Cc: Bjorn Helgaas , linux-pci@vger.kernel.org, xen-devel@lists.xenproject.org Subject: Re: [PATCH 3/3] xen/MSI: Retrieve MSI msg from cached msi_desc->msg Message-ID: <20140815035122.GB27697@laptop.dumpdata.com> References: <1408072477-10008-1-git-send-email-wangyijing@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <1408072477-10008-1-git-send-email-wangyijing@huawei.com> Sender: linux-pci-owner@vger.kernel.org List-ID: On Fri, Aug 15, 2014 at 11:14:37AM +0800, Yijing Wang wrote: > We had cached the MSI msg in __write_msi_msg(), > so we should retrieve the cached MSI msg directly, > not to access the MSI address/data hardware registers > again. Is this fixing a particular problem? Could you kindly explain to me when you do the __write_msi_msg before doing an read_msi_msg? The order of operation in this function is read, and then write. > > Signed-off-by: Yijing Wang > CC: Konrad Rzeszutek Wilk > CC: xen-devel@lists.xenproject.org > --- > arch/x86/pci/xen.c | 2 +- > 1 files changed, 1 insertions(+), 1 deletions(-) > > diff --git a/arch/x86/pci/xen.c b/arch/x86/pci/xen.c > index 4656099..7a74404 100644 > --- a/arch/x86/pci/xen.c > +++ b/arch/x86/pci/xen.c > @@ -228,7 +228,7 @@ static int xen_hvm_setup_msi_irqs(struct pci_dev *dev, int nvec, int type) > return 1; > > list_for_each_entry(msidesc, &dev->msi_list, list) { > - read_msi_msg(msidesc, &msg); > + get_cached_msi_msg(msidesc, &msg); > pirq = MSI_ADDR_EXT_DEST_ID(msg.address_hi) | > ((msg.address_lo >> MSI_ADDR_DEST_ID_SHIFT) & 0xff); > if (msg.data != XEN_PIRQ_MSI_DATA || > -- > 1.7.1 >