From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752803AbcD0Bch (ORCPT ); Tue, 26 Apr 2016 21:32:37 -0400 Received: from mga14.intel.com ([192.55.52.115]:13935 "EHLO mga14.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752624AbcD0Bcg convert rfc822-to-8bit (ORCPT ); Tue, 26 Apr 2016 21:32:36 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.24,539,1455004800"; d="scan'208";a="953670463" From: "Wu, Feng" To: Alex Williamson CC: "pbonzini@redhat.com" , "joro@8bytes.org" , "mtosatti@redhat.com" , "eric.auger@linaro.org" , "kvm@vger.kernel.org" , "iommu@lists.linux-foundation.org" , "linux-kernel@vger.kernel.org" , "Wu, Feng" Subject: RE: [PATCH v9 12/18] vfio: Register/unregister irq_bypass_producer Thread-Topic: [PATCH v9 12/18] vfio: Register/unregister irq_bypass_producer Thread-Index: AQHRn/dljO/DsspBjU6U6Hh9g/qHwZ+dB6jg Date: Wed, 27 Apr 2016 01:32:32 +0000 Message-ID: References: <1442586596-5920-1-git-send-email-feng.wu@intel.com> <1442586596-5920-13-git-send-email-feng.wu@intel.com> <20160426140816.67b8b37c@t450s.home> In-Reply-To: <20160426140816.67b8b37c@t450s.home> 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 > -----Original Message----- > From: Alex Williamson [mailto:alex.williamson@redhat.com] > Sent: Wednesday, April 27, 2016 4:08 AM > To: Wu, Feng > Cc: pbonzini@redhat.com; joro@8bytes.org; mtosatti@redhat.com; > eric.auger@linaro.org; kvm@vger.kernel.org; iommu@lists.linux- > foundation.org; linux-kernel@vger.kernel.org > Subject: Re: [PATCH v9 12/18] vfio: Register/unregister irq_bypass_producer > > On Fri, 18 Sep 2015 22:29:50 +0800 > Feng Wu wrote: > > @@ -360,6 +361,14 @@ static int vfio_msi_set_vector_signal(struct > vfio_pci_device *vdev, > > return ret; > > } > > > > + vdev->ctx[vector].producer.token = trigger; > > + vdev->ctx[vector].producer.irq = irq; > > + ret = irq_bypass_register_producer(&vdev->ctx[vector].producer); > > + if (unlikely(ret)) > > + dev_info(&pdev->dev, > > + "irq bypass producer (token %p) registeration fails: %d\n", > > + vdev->ctx[vector].producer.token, ret); > > + > > vdev->ctx[vector].trigger = trigger; > > > > return 0; > > Digging back into the IRQ producer/consumer thing, I'm not sure how we > should be handling a failure here, but it turns out that what we have > is pretty sub-optimal. Any sort of testing on AMD hits this dev_info > because kvm_arch_irq_bypass_add_producer() returns -EINVAL without > kvm_x86_ops->update_pi_irte which is only implemented for vmx. Clearly > we don't want to spew confusing error messages for a feature that does > not exist. > > The easiest option is to simply make this error silent, but should > registering a producer/consumer really fail due to a mismatch on the > other end or should the __connect sequence fail silently, which both > ends would know about (if they care) due to the add/del handshake > between them? Perhaps for now we simply need a stable suitable fix to > silence the dev_info above, but longer term, registration shouldn't > fail for mismatches like this. Thoughts? Thanks, Can we just return 0 when kvm_x86_ops->update_pi_irte is NULL in kvm_arch_irq_bypass_add_producer? Thanks, Feng > > Alex