Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752185AbaLSBqT (ORCPT ); Thu, 18 Dec 2014 20:46:19 -0500 Received: from mga09.intel.com ([134.134.136.24]:36438 "EHLO mga09.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751618AbaLSBqQ convert rfc822-to-8bit (ORCPT ); Thu, 18 Dec 2014 20:46:16 -0500 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.07,604,1413270000"; d="scan'208";a="656797077" From: "Zhang, Yang Z" To: "Wu, Feng" , "tglx@linutronix.de" , "mingo@redhat.com" , "hpa@zytor.com" , "x86@kernel.org" , "gleb@kernel.org" , "pbonzini@redhat.com" , "dwmw2@infradead.org" , "joro@8bytes.org" , "alex.williamson@redhat.com" , "jiang.liu@linux.intel.com" CC: "eric.auger@linaro.org" , "linux-kernel@vger.kernel.org" , "iommu@lists.linux-foundation.org" , "kvm@vger.kernel.org" Subject: RE: [v3 06/26] iommu, x86: No need to migrating irq for VT-d Posted-Interrupts Thread-Topic: [v3 06/26] iommu, x86: No need to migrating irq for VT-d Posted-Interrupts Thread-Index: AQHQFiFw/2wcwNXVUk6mLzPIG8E78JyVcJswgAC8KvCAAAEAoA== Date: Fri, 19 Dec 2014 01:46:06 +0000 Message-ID: References: <1418397300-10870-1-git-send-email-feng.wu@intel.com> <1418397300-10870-7-git-send-email-feng.wu@intel.com> In-Reply-To: Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [10.239.127.40] Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 8BIT MIME-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Wu, Feng wrote on 2014-12-19: > > > Zhang, Yang Z wrote on 2014-12-18: >> jiang.liu@linux.intel.com >> Cc: eric.auger@linaro.org; linux-kernel@vger.kernel.org; >> iommu@lists.linux-foundation.org; kvm@vger.kernel.org; Wu, Feng >> Subject: RE: [v3 06/26] iommu, x86: No need to migrating irq for >> VT-d Posted-Interrupts >> >> Feng Wu wrote on 2014-12-12: >>> We don't need to migrate the irqs for VT-d Posted-Interrupts here. >>> When 'pst' is set in IRTE, the associated irq will be posted to >>> guests instead of interrupt remapping. The destination of the >>> interrupt is set in Posted-Interrupts Descriptor, and the >>> migration happens during vCPU scheduling. >>> >>> However, we still update the cached irte here, which can be used >>> when changing back to remapping mode. >>> >>> Signed-off-by: Feng Wu >>> Reviewed-by: Jiang Liu >>> --- >>> drivers/iommu/intel_irq_remapping.c | 6 +++++- >>> 1 file changed, 5 insertions(+), 1 deletion(-) diff --git >>> a/drivers/iommu/intel_irq_remapping.c >>> b/drivers/iommu/intel_irq_remapping.c index 48c2051..ab9057a >>> 100644 >>> --- a/drivers/iommu/intel_irq_remapping.c +++ >>> b/drivers/iommu/intel_irq_remapping.c @@ -977,6 +977,7 @@ >>> intel_ir_set_affinity(struct irq_data *data, const struct cpumask >>> *mask, { >>> struct intel_ir_data *ir_data = data->chip_data; struct irte *irte = >>> &ir_data->irte_entry; + struct irte_pi *irte_pi = (struct irte_pi >>> *)irte; struct irq_cfg *cfg = irqd_cfg(data); struct irq_data *parent >>> = data->parent_data; int ret; >>> @@ -991,7 +992,10 @@ intel_ir_set_affinity(struct irq_data *data, >>> const struct cpumask *mask, >>> */ >>> irte->vector = cfg->vector; >>> irte->dest_id = IRTE_DEST(cfg->dest_apicid); >>> - modify_irte(&ir_data->irq_2_iommu, irte); >>> + >>> + /* We don't need to modify irte if the interrupt is for posting. */ >>> + if (irte_pi->pst != 1) >>> + modify_irte(&ir_data->irq_2_iommu, irte); >> >> What happens if user changes the IRQ affinity manually? > > If the IRQ is posted, its affinity is controlled by guest (irq <---> > vCPU <----> pCPU), it has no effect when host changes its affinity. That's the problem: User is able to changes it in host but it never takes effect since it is actually controlled by guest. I guess it will break the IRQ balance too. > > Thanks, > Feng > >> >>> >>> /* >>> * After this point, all the interrupts will start arriving >> >> >> Best regards, >> Yang >> Best regards, Yang -- 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/