From mboxrd@z Thu Jan 1 00:00:00 1970 From: Cornelia Huck Subject: Re: [PATCH v6 7/8] vhost: cross-endian support for legacy devices Date: Mon, 27 Apr 2015 11:17:29 +0200 Message-ID: <20150427111729.06a9492e.cornelia.huck@de.ibm.com> References: <20150424122211.19156.97626.stgit@bahia.local> <20150424122632.19156.88058.stgit@bahia.local> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20150424122632.19156.88058.stgit@bahia.local> Sender: linux-kernel-owner@vger.kernel.org To: Greg Kurz Cc: Rusty Russell , "Michael S. Tsirkin" , Thomas Huth , kvm@vger.kernel.org, linux-api@vger.kernel.org, linux-kernel@vger.kernel.org, virtualization@lists.linux-foundation.org List-Id: linux-api@vger.kernel.org On Fri, 24 Apr 2015 14:27:24 +0200 Greg Kurz wrote: > This patch brings cross-endian support to vhost when used to implement > legacy virtio devices. Since it is a relatively rare situation, the > feature availability is controlled by a kernel config option (not set > by default). > > The vq->is_le boolean field is added to cache the endianness to be > used for ring accesses. It defaults to native endian, as expected > by legacy virtio devices. When the ring gets active, we force little > endian if the device is modern. When the ring is deactivated, we > revert to the native endian default. > > If cross-endian was compiled in, a vq->user_be boolean field is added > so that userspace may request a specific endianness. This field is > used to override the default when activating the ring of a legacy > device. It has no effect on modern devices. > > Signed-off-by: Greg Kurz > --- > > Changes since v5: > - fixed description in Kconfig > - fixed error description in uapi header > - dropped useless semi-colon in the vhost_vq_reset_user_be() stub > > drivers/vhost/Kconfig | 15 ++++++++ > drivers/vhost/vhost.c | 85 +++++++++++++++++++++++++++++++++++++++++++- > drivers/vhost/vhost.h | 11 +++++- > include/uapi/linux/vhost.h | 14 +++++++ > 4 files changed, 122 insertions(+), 3 deletions(-) > Reviewed-by: Cornelia Huck