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>
Cc: stable@xxxxxxxxxxxxxxx # v4.10+
---
drivers/gpu/drm/i915/gvt/kvmgt.c | 14 +++++++++-----
1 file changed, 9 insertions(+), 5 deletions(-)
diff --git a/drivers/gpu/drm/i915/gvt/kvmgt.c b/drivers/gpu/drm/i915/gvt/kvmgt.c
index 56a8d6a..75a6e1d 100644
--- 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 intel_vgpu *vgpu)
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,
--
2.7.4