This is a note to let you know that I've just added the patch titled
drm/i915/gvt: Fix inconsistent locks holding sequence
to the 4.12-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
drm-i915-gvt-fix-inconsistent-locks-holding-sequence.patch
and it can be found in the queue-4.12 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From f16bd3dda2c8bf6699e808cd9cc540cfab10e60e Mon Sep 17 00:00:00 2001
From: Chuanxiao Dong <chuanxiao.dong@xxxxxxxxx>
Date: Mon, 26 Jun 2017 15:20:50 +0800
Subject: drm/i915/gvt: Fix inconsistent locks holding sequence
From: Chuanxiao Dong <chuanxiao.dong@xxxxxxxxx>
commit f16bd3dda2c8bf6699e808cd9cc540cfab10e60e upstream.
There are two kinds of locking sequence.
One is in the thread which is started by vfio ioctl to do
the iommu unmapping. The locking sequence is:
down_read(&group_lock) ----> mutex_lock(&cached_lock)
The other is in the vfio release thread which will unpin all
the cached pages. The lock sequence is:
mutex_lock(&cached_lock) ---> down_read(&group_lock)
And, the cache_lock is used to protect the rb tree of the cache
node and doing vfio unpin doesn't require this lock. Move the
vfio unpin out of the cache_lock protected region.
v2:
- use for style instead of do{}while(1). (Zhenyu)
Fixes: f30437c5e7bf ("drm/i915/gvt: add KVMGT support")
Signed-off-by: Chuanxiao Dong <chuanxiao.dong@xxxxxxxxx>
Cc: Zhenyu Wang <zhenyuw@xxxxxxxxxxxxxxx>
Signed-off-by: Zhenyu Wang <zhenyuw@xxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/gpu/drm/i915/gvt/kvmgt.c | 14 +++++++++-----
1 file changed, 9 insertions(+), 5 deletions(-)
--- a/drivers/gpu/drm/i915/gvt/kvmgt.c
+++ b/drivers/gpu/drm/i915/gvt/kvmgt.c
@@ -260,16 +260,20 @@ static void gvt_cache_destroy(struct int
struct device *dev = mdev_dev(vgpu->vdev.mdev);
unsigned long gfn;
- mutex_lock(&vgpu->vdev.cache_lock);
- while ((node = rb_first(&vgpu->vdev.cache))) {
+ for (;;) {
+ mutex_lock(&vgpu->vdev.cache_lock);
+ node = rb_first(&vgpu->vdev.cache);
+ if (!node) {
+ mutex_unlock(&vgpu->vdev.cache_lock);
+ break;
+ }
dma = rb_entry(node, struct gvt_dma, node);
gvt_dma_unmap_iova(vgpu, dma->iova);
gfn = dma->gfn;
-
- vfio_unpin_pages(dev, &gfn, 1);
__gvt_cache_remove_entry(vgpu, dma);
+ mutex_unlock(&vgpu->vdev.cache_lock);
+ vfio_unpin_pages(dev, &gfn, 1);
}
- mutex_unlock(&vgpu->vdev.cache_lock);
}
static struct intel_vgpu_type *intel_gvt_find_vgpu_type(struct intel_gvt *gvt,
Patches currently in stable-queue which might be from chuanxiao.dong@xxxxxxxxx are
queue-4.12/drm-i915-gvt-fix-possible-recursive-locking-issue.patch
queue-4.12/drm-i915-gvt-fix-inconsistent-locks-holding-sequence.patch
queue-4.12/vfio-remove-unnecessary-uses-of-vfio_container.group_lock.patch