Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751850AbbBVJwD (ORCPT ); Sun, 22 Feb 2015 04:52:03 -0500 Received: from mx1.redhat.com ([209.132.183.28]:41416 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751297AbbBVJwA (ORCPT ); Sun, 22 Feb 2015 04:52:00 -0500 Date: Sun, 22 Feb 2015 10:51:50 +0100 From: "Michael S. Tsirkin" To: Greg Kurz Cc: Cedric Le Goater , linux-kernel@vger.kernel.org, kvm@vger.kernel.org, virtualization@lists.linux-foundation.org Subject: Re: [PATCH 1/3] vhost: add VHOST_VRING_F_LEGACY_BIG_ENDIAN flag Message-ID: <20150222095150.GC17529@redhat.com> References: <20150220100724.18608.74654.stgit@bahia.local> <20150220100731.18608.2797.stgit@bahia.local> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20150220100731.18608.2797.stgit@bahia.local> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3113 Lines: 86 On Fri, Feb 20, 2015 at 11:07:39AM +0100, Greg Kurz wrote: > The VHOST_VRING_F_LEGACY_BIG_ENDIAN flag informs the kernel that the > associated device is big endian. Of course, this only makes sense for > legacy virtio devices since modern virtio devices are always little > endian. > > It will be used by the vhost memory accessors to byteswap vring data when > we have a legacy device, in case host and guest endianness differ. > > Signed-off-by: Greg Kurz > --- > drivers/vhost/vhost.c | 6 +++++- > drivers/vhost/vhost.h | 3 +++ > include/uapi/linux/vhost.h | 2 ++ > 3 files changed, 10 insertions(+), 1 deletion(-) > > diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c > index 2ee2826..dad3c37 100644 > --- a/drivers/vhost/vhost.c > +++ b/drivers/vhost/vhost.c > @@ -199,6 +199,7 @@ static void vhost_vq_reset(struct vhost_dev *dev, > vq->call = NULL; > vq->log_ctx = NULL; > vq->memory = NULL; > + vq->legacy_big_endian = false; > } > > static int vhost_worker(void *data) > @@ -701,7 +702,8 @@ long vhost_vring_ioctl(struct vhost_dev *d, int ioctl, void __user *argp) > r = -EFAULT; > break; > } > - if (a.flags & ~(0x1 << VHOST_VRING_F_LOG)) { > + if (a.flags & ~(0x1 << VHOST_VRING_F_LOG| > + 0x1 << VHOST_VRING_F_LEGACY_BIG_ENDIAN)) { whitespace damage here > r = -EOPNOTSUPP; > break; > } need to also make sure LEGACY_BIG_ENDIAN isn't set with VERSION_1. > @@ -751,6 +753,8 @@ long vhost_vring_ioctl(struct vhost_dev *d, int ioctl, void __user *argp) > vq->avail = (void __user *)(unsigned long)a.avail_user_addr; > vq->log_addr = a.log_guest_addr; > vq->used = (void __user *)(unsigned long)a.used_user_addr; > + vq->legacy_big_endian = > + !!(a.flags & (0x1 << VHOST_VRING_F_LEGACY_BIG_ENDIAN)); > break; > case VHOST_SET_VRING_KICK: > if (copy_from_user(&f, argp, sizeof f)) { > diff --git a/drivers/vhost/vhost.h b/drivers/vhost/vhost.h > index 8c1c792..ce2c68e 100644 > --- a/drivers/vhost/vhost.h > +++ b/drivers/vhost/vhost.h > @@ -106,6 +106,9 @@ struct vhost_virtqueue { > /* Log write descriptors */ > void __user *log_base; > struct vhost_log *log; > + > + /* We need to know the device endianness with legacy virtio. */ > + bool legacy_big_endian; > }; > > struct vhost_dev { > diff --git a/include/uapi/linux/vhost.h b/include/uapi/linux/vhost.h > index bb6a5b4..0bf4491 100644 > --- a/include/uapi/linux/vhost.h > +++ b/include/uapi/linux/vhost.h > @@ -34,6 +34,8 @@ struct vhost_vring_addr { > /* Flag values: */ > /* Whether log address is valid. If set enables logging. */ > #define VHOST_VRING_F_LOG 0 > + /* Whether we have a big-endian legacy virtio device. */ > +#define VHOST_VRING_F_LEGACY_BIG_ENDIAN 1 > > /* Start of array of descriptors (virtually contiguous) */ > __u64 desc_user_addr; -- 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/