From 4dbc5d9f4f791df8a5879f4a655f517adc7f56d1 Mon Sep 17 00:00:00 2001 From: Jason Wang Date: Fri, 20 Jan 2012 16:16:59 +0800 Subject: virtio: fix typos of memory barriers Note: this fixes a bug introduced recently in 7b21e34fd1c272e3a8c3846168f2f6287a4cd72b. Signed-off-by: Jason Wang Acked-by: Michael S. Tsirkin Signed-off-by: Rusty Russell diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c index 79e1b29..78428a8 100644 --- a/drivers/virtio/virtio_ring.c +++ b/drivers/virtio/virtio_ring.c @@ -35,7 +35,7 @@ #define virtio_rmb(vq) \ do { if ((vq)->weak_barriers) smp_rmb(); else rmb(); } while(0) #define virtio_wmb(vq) \ - do { if ((vq)->weak_barriers) smp_rmb(); else rmb(); } while(0) + do { if ((vq)->weak_barriers) smp_wmb(); else wmb(); } while(0) #else /* We must force memory ordering even if guest is UP since host could be * running on another CPU, but SMP barriers are defined to barrier() in that -- cgit v0.10.2 From a72caae21803b74e04e2afda5e035f149d4ea118 Mon Sep 17 00:00:00 2001 From: Jason Wang Date: Fri, 20 Jan 2012 16:17:08 +0800 Subject: virtio: correct the memory barrier in virtqueue_kick_prepare() Use virtio_mb() to make sure the available index to be exposed before checking the the avail event. Otherwise we may get stale value of avail event in guest and never kick the host after. Note: this fixes a bug introduced by ee7cd8981e15bcb365fc762afe3fc47b8242f630. Signed-off-by: Jason Wang Acked-by: Michael S. Tsirkin Signed-off-by: Rusty Russell Cc: stable@kernel.org diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c index 78428a8..5aa43c3 100644 --- a/drivers/virtio/virtio_ring.c +++ b/drivers/virtio/virtio_ring.c @@ -308,9 +308,9 @@ bool virtqueue_kick_prepare(struct virtqueue *_vq) bool needs_kick; START_USE(vq); - /* Descriptors and available array need to be set before we expose the - * new available array entries. */ - virtio_wmb(vq); + /* We need to expose available array entries before checking avail + * event. */ + virtio_mb(vq); old = vq->vring.avail->idx - vq->num_added; new = vq->vring.avail->idx; -- cgit v0.10.2 From 13289d5f2b2ee73583e6c65c46a1e0cd48c3ddc0 Mon Sep 17 00:00:00 2001 From: Rusty Russell Date: Sat, 28 Jan 2012 08:10:23 +1030 Subject: lguest: remove reference from Documentation/virtual/00-INDEX We're in tools/lguest now. Reported-by: Stephen Hemminger Signed-off-by: Rusty Russell diff --git a/Documentation/virtual/00-INDEX b/Documentation/virtual/00-INDEX index 8e60199..924bd46 100644 --- a/Documentation/virtual/00-INDEX +++ b/Documentation/virtual/00-INDEX @@ -4,8 +4,6 @@ Virtualization support in the Linux kernel. - this file. kvm/ - Kernel Virtual Machine. See also http://linux-kvm.org -lguest/ - - Extremely simple hypervisor for experimental/educational use. uml/ - User Mode Linux, builds/runs Linux kernel as a userspace program. virtio.txt -- cgit v0.10.2