From: Cornelia Huck <cornelia.huck@de.ibm.com>
To: Greg Kurz <gkurz@linux.vnet.ibm.com>
Cc: netdev@vger.kernel.org,
virtualization@lists.linux-foundation.org,
linux-kernel@vger.kernel.org, kvm@vger.kernel.org,
"Michael S. Tsirkin" <mst@redhat.com>
Subject: Re: [PATCH] vhost: move is_le setup to the backend
Date: Thu, 12 Nov 2015 13:37:14 +0100 [thread overview]
Message-ID: <20151112133714.58bd33dc.cornelia.huck@de.ibm.com> (raw)
In-Reply-To: <20151030114235.28847.63465.stgit@bahia.huguette.org>
On Fri, 30 Oct 2015 12:42:35 +0100
Greg Kurz <gkurz@linux.vnet.ibm.com> wrote:
> The vq->is_le field is used to fix endianness when accessing the vring via
> the cpu_to_vhost16() and vhost16_to_cpu() helpers in the following cases:
>
> 1) host is big endian and device is modern virtio
>
> 2) host has cross-endian support and device is legacy virtio with a different
> endianness than the host
>
> Both cases rely on the VHOST_SET_FEATURES ioctl, but 2) also needs the
> VHOST_SET_VRING_ENDIAN ioctl to be called by userspace. Since vq->is_le
> is only needed when the backend is active, it was decided to set it at
> backend start.
>
> This is currently done in vhost_init_used()->vhost_init_is_le() but it
> obfuscates the core vhost code. This patch moves the is_le setup to a
> dedicated function that is called from the backend code.
>
> Note vhost_net is the only backend that can pass vq->private_data == NULL to
> vhost_init_used(), hence the "if (sock)" branch.
>
> No behaviour change.
>
> Signed-off-by: Greg Kurz <gkurz@linux.vnet.ibm.com>
> ---
> drivers/vhost/net.c | 6 ++++++
> drivers/vhost/scsi.c | 3 +++
> drivers/vhost/test.c | 2 ++
> drivers/vhost/vhost.c | 12 +++++++-----
> drivers/vhost/vhost.h | 1 +
> 5 files changed, 19 insertions(+), 5 deletions(-)
Makes sense.
Reviewed-by: Cornelia Huck <cornelia.huck@de.ibm.com>
next prev parent reply other threads:[~2015-11-12 12:37 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-10-30 11:42 [PATCH] vhost: move is_le setup to the backend Greg Kurz
2015-11-02 20:09 ` David Miller
2015-11-12 8:30 ` Greg Kurz
2015-11-12 12:37 ` Cornelia Huck [this message]
2015-11-12 13:46 ` Michael S. Tsirkin
2015-11-12 14:28 ` Greg Kurz
2015-12-16 13:52 ` Greg Kurz
2016-01-11 14:39 Greg Kurz
2016-01-12 10:01 ` Michael S. Tsirkin
2016-01-12 10:31 ` Greg Kurz
2016-01-12 10:48 ` Michael S. Tsirkin
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