From 09047ffb4faaebd032d24f993e1e290c0369a7a3 Mon Sep 17 00:00:00 2001 From: Thomas Huth Date: Fri, 3 Jul 2015 19:13:35 +0200 Subject: [PATCH 025/100] vhost: set vring endianness for legacy virtio Message-id: <1435950819-10991-4-git-send-email-thuth@redhat.com> Patchwork-id: 66696 O-Subject: [RHEL7.2 qemu-kvm-rhev PATCH 3/7] vhost: set vring endianness for legacy virtio Bugzilla: 1225715 RH-Acked-by: Michael S. Tsirkin RH-Acked-by: Laurent Vivier RH-Acked-by: David Gibson From: Greg Kurz Legacy virtio is native endian: if the guest and host endianness differ, we have to tell vhost so it can swap bytes where appropriate. This is done through a vhost ring ioctl. Signed-off-by: Greg Kurz Reviewed-by: Michael S. Tsirkin Signed-off-by: Michael S. Tsirkin (cherry picked from commit 04b7a1523d65bb5c78832098cf3108a1aadcaf8a) Signed-off-by: Thomas Huth Signed-off-by: Miroslav Rezanina --- hw/virtio/vhost.c | 50 +++++++++++++++++++++++++++++++++++++++++++++++++- 1 file changed, 49 insertions(+), 1 deletion(-) diff --git a/hw/virtio/vhost.c b/hw/virtio/vhost.c index 54851b7..1d7b939 100644 --- a/hw/virtio/vhost.c +++ b/hw/virtio/vhost.c @@ -17,9 +17,11 @@ #include "hw/hw.h" #include "qemu/atomic.h" #include "qemu/range.h" +#include "qemu/error-report.h" #include #include "exec/address-spaces.h" #include "hw/virtio/virtio-bus.h" +#include "hw/virtio/virtio-access.h" #include "migration/migration.h" static void vhost_dev_sync_region(struct vhost_dev *dev, @@ -647,6 +649,27 @@ static void vhost_log_stop(MemoryListener *listener, /* FIXME: implement */ } +static int vhost_virtqueue_set_vring_endian_legacy(struct vhost_dev *dev, + bool is_big_endian, + int vhost_vq_index) +{ + struct vhost_vring_state s = { + .index = vhost_vq_index, + .num = is_big_endian + }; + + if (!dev->vhost_ops->vhost_call(dev, VHOST_SET_VRING_ENDIAN, &s)) { + return 0; + } + + if (errno == ENOTTY) { + error_report("vhost does not support cross-endian"); + return -ENOSYS; + } + + return -errno; +} + static int vhost_virtqueue_start(struct vhost_dev *dev, struct VirtIODevice *vdev, struct vhost_virtqueue *vq, @@ -677,6 +700,16 @@ static int vhost_virtqueue_start(struct vhost_dev *dev, return -errno; } + if (!virtio_has_feature(vdev, VIRTIO_F_VERSION_1) && + virtio_legacy_is_cross_endian(vdev)) { + r = vhost_virtqueue_set_vring_endian_legacy(dev, + virtio_is_big_endian(vdev), + vhost_vq_index); + if (r) { + return -errno; + } + } + s = l = virtio_queue_get_desc_size(vdev, idx); a = virtio_queue_get_desc_addr(vdev, idx); vq->desc = cpu_physical_memory_map(a, &l, 0); @@ -747,8 +780,9 @@ static void vhost_virtqueue_stop(struct vhost_dev *dev, struct vhost_virtqueue *vq, unsigned idx) { + int vhost_vq_index = idx - dev->vq_index; struct vhost_vring_state state = { - .index = idx - dev->vq_index + .index = vhost_vq_index, }; int r; assert(idx >= dev->vq_index && idx < dev->vq_index + dev->nvqs); @@ -759,6 +793,20 @@ static void vhost_virtqueue_stop(struct vhost_dev *dev, } virtio_queue_set_last_avail_idx(vdev, idx, state.num); virtio_queue_invalidate_signalled_used(vdev, idx); + + /* In the cross-endian case, we need to reset the vring endianness to + * native as legacy devices expect so by default. + */ + if (!virtio_has_feature(vdev, VIRTIO_F_VERSION_1) && + virtio_legacy_is_cross_endian(vdev)) { + r = vhost_virtqueue_set_vring_endian_legacy(dev, + !virtio_is_big_endian(vdev), + vhost_vq_index); + if (r < 0) { + error_report("failed to reset vring endianness"); + } + } + assert (r >= 0); cpu_physical_memory_unmap(vq->ring, virtio_queue_get_ring_size(vdev, idx), 0, virtio_queue_get_ring_size(vdev, idx)); -- 1.8.3.1