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Date: Sat, 03 Oct 2020 12:01:52 +0200 From: Greg Kurz <groug@...d.org> To: "Michael S. Tsirkin" <mst@...hat.com>, Jason Wang <jasowang@...hat.com> Cc: kvm@...r.kernel.org, virtualization@...ts.linux-foundation.org, netdev@...r.kernel.org, linux-kernel@...r.kernel.org, qemu-devel@...gnu.org, Laurent Vivier <laurent@...ier.eu>, David Gibson <david@...son.dropbear.id.au> Subject: [PATCH v3 1/3] vhost: Don't call access_ok() when using IOTLB When the IOTLB device is enabled, the vring addresses we get from userspace are GIOVAs. It is thus wrong to pass them down to access_ok() which only takes HVAs. Access validation is done at prefetch time with IOTLB. Teach vq_access_ok() about that by moving the (vq->iotlb) check from vhost_vq_access_ok() to vq_access_ok(). This prevents vhost_vring_set_addr() to fail when verifying the accesses. No behavior change for vhost_vq_access_ok(). BugLink: https://bugzilla.redhat.com/show_bug.cgi?id=1883084 Fixes: 6b1e6cc7855b ("vhost: new device IOTLB API") Cc: jasowang@...hat.com CC: stable@...r.kernel.org # 4.14+ Signed-off-by: Greg Kurz <groug@...d.org> Acked-by: Jason Wang <jasowang@...hat.com> --- drivers/vhost/vhost.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c index b45519ca66a7..c3b49975dc28 100644 --- a/drivers/vhost/vhost.c +++ b/drivers/vhost/vhost.c @@ -1290,6 +1290,11 @@ static bool vq_access_ok(struct vhost_virtqueue *vq, unsigned int num, vring_used_t __user *used) { + /* If an IOTLB device is present, the vring addresses are + * GIOVAs. Access validation occurs at prefetch time. */ + if (vq->iotlb) + return true; + return access_ok(desc, vhost_get_desc_size(vq, num)) && access_ok(avail, vhost_get_avail_size(vq, num)) && access_ok(used, vhost_get_used_size(vq, num)); @@ -1383,10 +1388,6 @@ bool vhost_vq_access_ok(struct vhost_virtqueue *vq) if (!vq_log_access_ok(vq, vq->log_base)) return false; - /* Access validation occurs at prefetch time with IOTLB */ - if (vq->iotlb) - return true; - return vq_access_ok(vq, vq->num, vq->desc, vq->avail, vq->used); } EXPORT_SYMBOL_GPL(vhost_vq_access_ok);
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