Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933067AbaJ2N7u (ORCPT ); Wed, 29 Oct 2014 09:59:50 -0400 Received: from smtp02.citrix.com ([66.165.176.63]:25278 "EHLO SMTP02.CITRIX.COM" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932801AbaJ2N7s (ORCPT ); Wed, 29 Oct 2014 09:59:48 -0400 X-IronPort-AV: E=Sophos;i="5.04,810,1406592000"; d="scan'208";a="187391153" Message-ID: <5450F2CE.8070104@citrix.com> Date: Wed, 29 Oct 2014 13:59:42 +0000 From: David Vrabel User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Icedove/24.5.0 MIME-Version: 1.0 To: Boris Ostrovsky , , , CC: , , Subject: Re: [Xen-devel] [PATCH v2 0/2] xen/pci: Use APIC for MSIs when APIC virtualization is supported References: <1414425953-13987-1-git-send-email-boris.ostrovsky@oracle.com> In-Reply-To: <1414425953-13987-1-git-send-email-boris.ostrovsky@oracle.com> Content-Type: text/plain; charset="ISO-8859-1" Content-Transfer-Encoding: 7bit X-DLP: MIA2 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 27/10/14 16:05, Boris Ostrovsky wrote: > 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 Applied to devel/for-linus-3.19. Thanks. David -- 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/