Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933503AbaLCAZt (ORCPT ); Tue, 2 Dec 2014 19:25:49 -0500 Received: from ppsw-52.csi.cam.ac.uk ([131.111.8.152]:51533 "EHLO ppsw-52.csi.cam.ac.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750877AbaLCAZs (ORCPT ); Tue, 2 Dec 2014 19:25:48 -0500 X-Greylist: delayed 924 seconds by postgrey-1.27 at vger.kernel.org; Tue, 02 Dec 2014 19:25:48 EST X-Cam-AntiVirus: no malware found X-Cam-ScannerInfo: http://www.cam.ac.uk/cs/email/scanner/ Message-ID: <547E54EB.8070707@citrix.com> Date: Wed, 03 Dec 2014 00:10:19 +0000 From: Andrew Cooper User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:24.0) Gecko/20100101 Thunderbird/24.6.0 MIME-Version: 1.0 To: Konrad Rzeszutek Wilk , Boris Ostrovsky CC: linux-kernel@vger.kernel.org, xen-devel@lists.xen.org, david.vrabel@citrix.com, jun.nakajima@intel.com, stefano.stabellini@eu.citrix.com Subject: Re: [Xen-devel] [PATCH v4 0/2] xen/pci: Use APIC for MSIs when APIC virtualization is supported References: <1417551553-22234-1-git-send-email-boris.ostrovsky@oracle.com> <20141202204825.GS357@laptop.dumpdata.com> In-Reply-To: <20141202204825.GS357@laptop.dumpdata.com> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 02/12/2014 20:48, Konrad Rzeszutek Wilk wrote: > On Tue, Dec 02, 2014 at 03:19:11PM -0500, Boris Ostrovsky wrote: >> Changes in v4: >> * Added comment describing what we check for in pci_xen_init() >> > Reviewed-by: Konrad Rzeszutek Wilk Reviewed-by: Andrew Cooper > >> Changes in v3: >> * Explicitly include asm/apic.h in arch/x86/pci/xen.c for !CONFIG_SMP. >> >> Changes in v2: >> * New version of cpuid.h file from Xen tree (with a couple of style adjustments) >> * Whitespace cleanup >> >> Currently HVM guests handle MSI interrupts using pirqs/event channels, allowing >> us to not issue APIC accesses that result in somewhat expensive VMEXITs. When >> hardware supports APIC virtualization we don't need to use pirqs anymore >> since now guest's APIC accesses can be handled by the processor itself. >> >> There are two patches in this series: >> >> 1. Move setting of x86_msi ops to a later point. The reason for doing so is that >> we currently decide whether or not to use pirqs before kernel had a chance to >> see whether it should be using x2APIC instead of plain APIC. Since hardware may >> virtualize either or both of those two we can only make pirqs vs. APIC selection >> after kernel has settled down on which APIC version it will use. (Note that >> currently x2APIC is not used by HVM guests so technically this patch is not >> necessary. However, it probably makes sense to apply it now to avoid >> forgetting to do it when we enable x2APIC). >> >> 2. Set x86_msi ops to use pirqs only when APIC virtualization is not available. >> The commit message describes performance improvements that this change brings. >> >> >> Boris Ostrovsky (2): >> xen/pci: Defer initialization of MSI ops on HVM guests until after >> x2APIC has been set up >> xen/pci: Use APIC directly when APIC virtualization is supported by >> hardware >> >> arch/x86/include/asm/xen/cpuid.h | 91 ++++++++++++++++++++++++++++++++++++++++ >> arch/x86/pci/xen.c | 31 +++++++++++++- >> 2 files changed, 120 insertions(+), 2 deletions(-) >> create mode 100644 arch/x86/include/asm/xen/cpuid.h >> >> -- >> 1.8.1.4 >> > _______________________________________________ > Xen-devel mailing list > Xen-devel@lists.xen.org > http://lists.xen.org/xen-devel -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/