From mboxrd@z Thu Jan 1 00:00:00 1970 From: hch@lst.de (Christoph Hellwig) Date: Thu, 27 Dec 2018 14:08:34 +0100 Subject: [PATCH 2/2] nvme pci: try to allocate multiple irq vectors again in case of -EINVAL In-Reply-To: <20181227082136.GA14423@ming.t460p> References: <20181226103755.2101-1-ming.lei@redhat.com> <20181226103755.2101-3-ming.lei@redhat.com> <20181226182027.GA5866@lst.de> <20181227082136.GA14423@ming.t460p> Message-ID: <20181227130834.GA22967@lst.de> On Thu, Dec 27, 2018@04:21:38PM +0800, Ming Lei wrote: > On Wed, Dec 26, 2018@07:20:27PM +0100, Christoph Hellwig wrote: > > On Wed, Dec 26, 2018@06:37:55PM +0800, Ming Lei wrote: > > > It is observed on QEMU that pci_alloc_irq_vectors_affinity() may > > > returns -EINVAL when the requested number is too big(such as 64). > > > > Which is not how this API is supposed to work and documented to work. > > > > We need to fix pci_alloc_irq_vectors_affinity to not return a spurious > > error and just return the allocated number of vectors instead of > > hacking around that in drivers. > > Yeah, you are right. > > The issue is that QEMU nvme-pci is MSIX-capable only, and hasn't MSI > capability. > > __pci_enable_msix_range() actually returns -ENOSPC, but __pci_enable_msi_range() > returns -EINVAL because dev->msi_cap is zero. > > Maybe we need the following fix? Should it matter? We still get a negative vecs back, and still fall back to the next option. Unless ther are no irqs available at all for the selected types pci_alloc_irq_vectors_affinity should never return an error. From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_MUTT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id EBC40C43387 for ; Thu, 27 Dec 2018 13:08:37 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A78992070C for ; Thu, 27 Dec 2018 13:08:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730519AbeL0NIh (ORCPT ); Thu, 27 Dec 2018 08:08:37 -0500 Received: from verein.lst.de ([213.95.11.211]:56578 "EHLO newverein.lst.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727601AbeL0NIg (ORCPT ); Thu, 27 Dec 2018 08:08:36 -0500 Received: by newverein.lst.de (Postfix, from userid 2407) id C0ED268AFE; Thu, 27 Dec 2018 14:08:34 +0100 (CET) Date: Thu, 27 Dec 2018 14:08:34 +0100 From: Christoph Hellwig To: Ming Lei Cc: Christoph Hellwig , Bjorn Helgaas , Keith Busch , Jens Axboe , linux-nvme@lists.infradead.org, linux-pci@vger.kernel.org Subject: Re: [PATCH 2/2] nvme pci: try to allocate multiple irq vectors again in case of -EINVAL Message-ID: <20181227130834.GA22967@lst.de> References: <20181226103755.2101-1-ming.lei@redhat.com> <20181226103755.2101-3-ming.lei@redhat.com> <20181226182027.GA5866@lst.de> <20181227082136.GA14423@ming.t460p> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20181227082136.GA14423@ming.t460p> User-Agent: Mutt/1.5.17 (2007-11-01) Sender: linux-pci-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org On Thu, Dec 27, 2018 at 04:21:38PM +0800, Ming Lei wrote: > On Wed, Dec 26, 2018 at 07:20:27PM +0100, Christoph Hellwig wrote: > > On Wed, Dec 26, 2018 at 06:37:55PM +0800, Ming Lei wrote: > > > It is observed on QEMU that pci_alloc_irq_vectors_affinity() may > > > returns -EINVAL when the requested number is too big(such as 64). > > > > Which is not how this API is supposed to work and documented to work. > > > > We need to fix pci_alloc_irq_vectors_affinity to not return a spurious > > error and just return the allocated number of vectors instead of > > hacking around that in drivers. > > Yeah, you are right. > > The issue is that QEMU nvme-pci is MSIX-capable only, and hasn't MSI > capability. > > __pci_enable_msix_range() actually returns -ENOSPC, but __pci_enable_msi_range() > returns -EINVAL because dev->msi_cap is zero. > > Maybe we need the following fix? Should it matter? We still get a negative vecs back, and still fall back to the next option. Unless ther are no irqs available at all for the selected types pci_alloc_irq_vectors_affinity should never return an error.