From 254084986a8a30b2b56979da9ddd32dc211c0b2e Mon Sep 17 00:00:00 2001 From: Chuanxiao Dong Date: Mon, 26 Jun 2017 15:20:50 +0800 Subject: [PATCH] drm/i915/gvt: Fix inconsistent locks holding sequence 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 Cc: Zhenyu Wang Signed-off-by: Zhenyu Wang Signed-off-by: Greg Kroah-Hartman --- 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 1ae0b4083ce10..fd0c85f9ef3c3 100644 --- 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 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, -- 2.47.3