lkml.org 
[lkml]   [2017]   [Jul]   [25]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH 4.12 122/196] drm/i915/gvt: Fix inconsistent locks holding sequence
Date
4.12-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Chuanxiao Dong <chuanxiao.dong@intel.com>

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@intel.com>
Cc: Zhenyu Wang <zhenyuw@linux.intel.com>
Signed-off-by: Zhenyu Wang <zhenyuw@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
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
@@ -232,16 +232,20 @@ 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,

\
 
 \ /
  Last update: 2017-07-25 21:46    [W:0.434 / U:17.272 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site