Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751559AbbBJG5y (ORCPT ); Tue, 10 Feb 2015 01:57:54 -0500 Received: from mx1.redhat.com ([209.132.183.28]:41654 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751094AbbBJG5x (ORCPT ); Tue, 10 Feb 2015 01:57:53 -0500 Date: Tue, 10 Feb 2015 07:57:46 +0100 From: "Michael S. Tsirkin" To: Rusty Russell Cc: lkml , virtualization@lists.linux-foundation.org Subject: Re: [PATCH] virtio_pci: use 16-bit accessor for queue_enable. Message-ID: <20150210065746.GA30095@redhat.com> References: <87twyuw9yi.fsf@rustcorp.com.au> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <87twyuw9yi.fsf@rustcorp.com.au> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1667 Lines: 41 On Tue, Feb 10, 2015 at 05:05:01PM +1030, Rusty Russell wrote: > Since PCI is little endian, 8-bit access might work, but the spec section > is very clear on this: > > 4.1.3.1 Driver Requirements: PCI Device Layout > > The driver MUST access each field using the “natural” access method, > i.e. 32-bit accesses for 32-bit fields, 16-bit accesses for 16-bit > fields and 8-bit accesses for 8-bit fields. > > Signed-off-by: Rusty Russell Acked-by: Michael S. Tsirkin > diff --git a/drivers/virtio/virtio_pci_modern.c b/drivers/virtio/virtio_pci_modern.c > index f16e462cb4ef..2aa38e59db2e 100644 > --- a/drivers/virtio/virtio_pci_modern.c > +++ b/drivers/virtio/virtio_pci_modern.c > @@ -294,7 +294,7 @@ static struct virtqueue *setup_vq(struct virtio_pci_device *vp_dev, > > /* Check if queue is either not available or already active. */ > num = ioread16(&cfg->queue_size); > - if (!num || ioread8(&cfg->queue_enable)) > + if (!num || ioread16(&cfg->queue_enable)) > return ERR_PTR(-ENOENT); > > if (num & (num - 1)) { > @@ -394,7 +394,7 @@ static int vp_modern_find_vqs(struct virtio_device *vdev, unsigned nvqs, > */ > list_for_each_entry(vq, &vdev->vqs, list) { > iowrite16(vq->index, &vp_dev->common->queue_select); > - iowrite8(1, &vp_dev->common->queue_enable); > + iowrite16(1, &vp_dev->common->queue_enable); > } > > return 0; -- 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/