Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756940Ab2FDLVF (ORCPT ); Mon, 4 Jun 2012 07:21:05 -0400 Received: from www.linutronix.de ([62.245.132.108]:40819 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752670Ab2FDLVD (ORCPT ); Mon, 4 Jun 2012 07:21:03 -0400 Date: Mon, 4 Jun 2012 13:21:01 +0200 (CEST) From: Thomas Gleixner To: Avi Kivity cc: Jan Kiszka , Alex Williamson , "kvm@vger.kernel.org" , "mtosatti@redhat.com" , "linux-kernel@vger.kernel.org" , "yongjie.ren@intel.com" Subject: Re: [PATCH] KVM: Use IRQF_ONESHOT for assigned device MSI interrupts In-Reply-To: <4FCB2359.9020505@redhat.com> Message-ID: References: <20120601161521.26935.25606.stgit@bling.home> <4FC8F042.5050600@siemens.com> <1338570192.23475.25.camel@bling.home> <4FC8F867.7080103@siemens.com> <1338573558.23475.41.camel@bling.home> <4FC90961.8030701@siemens.com> <4FCB2359.9020505@redhat.com> User-Agent: Alpine 2.02 (LFD 1266 2009-07-14) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-Linutronix-Spam-Score: -1.0 X-Linutronix-Spam-Level: - X-Linutronix-Spam-Status: No , -1.0 points, 5.0 required, ALL_TRUSTED=-1,SHORTCIRCUIT=-0.0001 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2692 Lines: 77 On Sun, 3 Jun 2012, Avi Kivity wrote: > On 06/01/2012 09:26 PM, Jan Kiszka wrote: > > > >> you suggesting we need a request_edge_threaded_only_irq() API? Thanks, > > > > I'm just wondering if that restriction for threaded IRQs is really > > necessary for all use cases we have. Threaded MSIs do not appear to me > > like have to be handled that conservatively, but maybe I'm missing some > > detail. > > > > btw, I'm hoping we can unthread assigned MSIs. If the delivery is > unicast, we can precalculate everything and all the handler has to do is > set the IRR, KVM_REQ_EVENT, and kick the vcpu. All of these can be done > from interrupt context with just RCU locking. There is really no need to run MSI/MSI-X interrupts threaded for KVM. I'm running the patch below for quite some time and it works like a charm. Thanks, tglx ---- Index: linux-2.6/virt/kvm/assigned-dev.c =================================================================== --- linux-2.6.orig/virt/kvm/assigned-dev.c +++ linux-2.6/virt/kvm/assigned-dev.c @@ -105,7 +105,7 @@ static irqreturn_t kvm_assigned_dev_thre } #ifdef __KVM_HAVE_MSI -static irqreturn_t kvm_assigned_dev_thread_msi(int irq, void *dev_id) +static irqreturn_t kvm_assigned_dev_msi_handler(int irq, void *dev_id) { struct kvm_assigned_dev_kernel *assigned_dev = dev_id; @@ -117,7 +117,7 @@ static irqreturn_t kvm_assigned_dev_thre #endif #ifdef __KVM_HAVE_MSIX -static irqreturn_t kvm_assigned_dev_thread_msix(int irq, void *dev_id) +static irqreturn_t kvm_assigned_dev_msix_handler(int irq, void *dev_id) { struct kvm_assigned_dev_kernel *assigned_dev = dev_id; int index = find_index_from_host_irq(assigned_dev, irq); @@ -346,9 +346,8 @@ static int assigned_device_enable_host_m } dev->host_irq = dev->dev->irq; - if (request_threaded_irq(dev->host_irq, NULL, - kvm_assigned_dev_thread_msi, 0, - dev->irq_name, dev)) { + if (request_irq(dev->host_irq, kvm_assigned_dev_msi_handler, 0, + dev->irq_name, dev)) { pci_disable_msi(dev->dev); return -EIO; } @@ -373,9 +372,9 @@ static int assigned_device_enable_host_m return r; for (i = 0; i < dev->entries_nr; i++) { - r = request_threaded_irq(dev->host_msix_entries[i].vector, - NULL, kvm_assigned_dev_thread_msix, - 0, dev->irq_name, dev); + r = request_irq(dev->host_msix_entries[i].vector, + kvm_assigned_dev_msix_handler, 0, + dev->irq_name, dev); if (r) goto err; } -- 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/