From 04b7a1523d65bb5c78832098cf3108a1aadcaf8a Mon Sep 17 00:00:00 2001 From: Greg Kurz Date: Wed, 17 Jun 2015 15:23:39 +0200 Subject: vhost: set vring endianness for legacy virtio 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 --- hw/virtio/vhost.c | 50 +++++++++++++++++++++++++++++++++++++++++++++++++- 1 file changed, 49 insertions(+), 1 deletion(-) (limited to 'hw/virtio') diff --git a/hw/virtio/vhost.c b/hw/virtio/vhost.c index 7908255503..7ea45b391c 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 struct vhost_log *vhost_log; @@ -686,6 +688,27 @@ 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, @@ -716,6 +739,16 @@ 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); @@ -786,8 +819,9 @@ 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); @@ -798,6 +832,20 @@ 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)); -- cgit v1.2.3 From 1e7398a140f7a6bd9f5a438e7ad0f1ef50990e25 Mon Sep 17 00:00:00 2001 From: Pankaj Gupta Date: Tue, 16 Jun 2015 13:48:59 +0530 Subject: vhost: enable vhost without without MSI-X We use vhostforce to enable vhost even if Guests don't have MSI-X support and we fall back to QEMU virtio-net. This gives a very small performance gain, but the disadvantage is that guest now controls which virtio code is running (qemu or vhost) so our attack surface is doubled. This patch will enable vhost unconditionally whenever it's requested. For compatibility, enable vhost when vhostforce is set, as well. Signed-off-by: Pankaj Gupta Reviewed-by: Michael S. Tsirkin Signed-off-by: Michael S. Tsirkin Reviewed-by: Jason Wang --- hw/virtio/vhost.c | 14 +------------- 1 file changed, 1 insertion(+), 13 deletions(-) (limited to 'hw/virtio') diff --git a/hw/virtio/vhost.c b/hw/virtio/vhost.c index 7ea45b391c..b84d21cf7e 100644 --- a/hw/virtio/vhost.c +++ b/hw/virtio/vhost.c @@ -898,7 +898,7 @@ static void vhost_virtqueue_cleanup(struct vhost_virtqueue *vq) } int vhost_dev_init(struct vhost_dev *hdev, void *opaque, - VhostBackendType backend_type, bool force) + VhostBackendType backend_type) { uint64_t features; int i, r; @@ -961,7 +961,6 @@ int vhost_dev_init(struct vhost_dev *hdev, void *opaque, hdev->started = false; hdev->memory_changed = false; memory_listener_register(&hdev->memory_listener, &address_space_memory); - hdev->force = force; return 0; fail_vq: while (--i >= 0) { @@ -989,17 +988,6 @@ void vhost_dev_cleanup(struct vhost_dev *hdev) hdev->vhost_ops->vhost_backend_cleanup(hdev); } -bool vhost_dev_query(struct vhost_dev *hdev, VirtIODevice *vdev) -{ - BusState *qbus = BUS(qdev_get_parent_bus(DEVICE(vdev))); - VirtioBusState *vbus = VIRTIO_BUS(qbus); - VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(vbus); - - return !k->query_guest_notifiers || - k->query_guest_notifiers(qbus->parent) || - hdev->force; -} - /* Stop processing guest IO notifications in qemu. * Start processing them in vhost in kernel. */ -- cgit v1.2.3