mirror of https://gitee.com/openkylin/linux.git
drm/i915/gvt: Fix possible recursive locking issue
vfio_unpin_pages will hold a read semaphore however it is already hold
in the same thread by vfio ioctl. It will cause below warning:
[ 5102.127454] ============================================
[ 5102.133379] WARNING: possible recursive locking detected
[ 5102.139304] 4.12.0-rc4+ #3 Not tainted
[ 5102.143483] --------------------------------------------
[ 5102.149407] qemu-system-x86/1620 is trying to acquire lock:
[ 5102.155624] (&container->group_lock){++++++}, at: [<ffffffff817768c6>] vfio_unpin_pages+0x96/0xf0
[ 5102.165626]
but task is already holding lock:
[ 5102.172134] (&container->group_lock){++++++}, at: [<ffffffff8177728f>] vfio_fops_unl_ioctl+0x5f/0x280
[ 5102.182522]
other info that might help us debug this:
[ 5102.189806] Possible unsafe locking scenario:
[ 5102.196411] CPU0
[ 5102.199136] ----
[ 5102.201861] lock(&container->group_lock);
[ 5102.206527] lock(&container->group_lock);
[ 5102.211191]
*** DEADLOCK ***
[ 5102.217796] May be due to missing lock nesting notation
[ 5102.225370] 3 locks held by qemu-system-x86/1620:
[ 5102.230618] #0: (&container->group_lock){++++++}, at: [<ffffffff8177728f>] vfio_fops_unl_ioctl+0x5f/0x280
[ 5102.241482] #1: (&(&iommu->notifier)->rwsem){++++..}, at: [<ffffffff810de775>] __blocking_notifier_call_chain+0x35/0x70
[ 5102.253713] #2: (&vgpu->vdev.cache_lock){+.+...}, at: [<ffffffff8157b007>] intel_vgpu_iommu_notifier+0x77/0x120
[ 5102.265163]
stack backtrace:
[ 5102.270022] CPU: 5 PID: 1620 Comm: qemu-system-x86 Not tainted 4.12.0-rc4+ #3
[ 5102.277991] Hardware name: Intel Corporation S1200RP/S1200RP, BIOS S1200RP.86B.03.01.APER.061220151418 06/12/2015
[ 5102.289445] Call Trace:
[ 5102.292175] dump_stack+0x85/0xc7
[ 5102.295871] validate_chain.isra.21+0x9da/0xaf0
[ 5102.300925] __lock_acquire+0x405/0x820
[ 5102.305202] lock_acquire+0xc7/0x220
[ 5102.309191] ? vfio_unpin_pages+0x96/0xf0
[ 5102.313666] down_read+0x2b/0x50
[ 5102.317259] ? vfio_unpin_pages+0x96/0xf0
[ 5102.321732] vfio_unpin_pages+0x96/0xf0
[ 5102.326024] intel_vgpu_iommu_notifier+0xe5/0x120
[ 5102.331283] notifier_call_chain+0x4a/0x70
[ 5102.335851] __blocking_notifier_call_chain+0x4d/0x70
[ 5102.341490] blocking_notifier_call_chain+0x16/0x20
[ 5102.346935] vfio_iommu_type1_ioctl+0x87b/0x920
[ 5102.351994] vfio_fops_unl_ioctl+0x81/0x280
[ 5102.356660] ? __fget+0xf0/0x210
[ 5102.360261] do_vfs_ioctl+0x93/0x6a0
[ 5102.364247] ? __fget+0x111/0x210
[ 5102.367942] SyS_ioctl+0x41/0x70
[ 5102.371542] entry_SYSCALL_64_fastpath+0x1f/0xbe
put the vfio_unpin_pages in a workqueue can fix this.
v2:
- use for style instead of do{}while(1). (Zhenyu)
v3:
- rename gvt_cache_mark to gvt_cache_mark_remove. (Zhenyu)
Fixes: 659643f7d8 ("drm/i915/gvt/kvmgt: add vfio/mdev support to KVMGT")
Signed-off-by: Chuanxiao Dong <chuanxiao.dong@intel.com>
Cc: Zhenyu Wang <zhenyuw@linux.intel.com>
Cc: stable@vger.kernel.org # v4.10+
Signed-off-by: Zhenyu Wang <zhenyuw@linux.intel.com>
This commit is contained in:
Chuanxiao Dong
Zhenyu Wang
parent
e274086e47
commit
62d02fd1f8
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@ -183,6 +183,9 @@ struct intel_vgpu {
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struct kvm *kvm;
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struct work_struct release_work;
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atomic_t released;
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struct work_struct unpin_work;
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spinlock_t unpin_lock; /* To protect unpin_list */
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struct list_head unpin_list;
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} vdev;
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#endif
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};
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@ -78,6 +78,7 @@ struct gvt_dma {
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struct rb_node node;
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gfn_t gfn;
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unsigned long iova;
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struct list_head list;
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};
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static inline bool handle_valid(unsigned long handle)
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@ -166,6 +167,7 @@ static void gvt_cache_add(struct intel_vgpu *vgpu, gfn_t gfn,
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new->gfn = gfn;
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new->iova = iova;
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INIT_LIST_HEAD(&new->list);
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mutex_lock(&vgpu->vdev.cache_lock);
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while (*link) {
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@ -197,26 +199,52 @@ static void __gvt_cache_remove_entry(struct intel_vgpu *vgpu,
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kfree(entry);
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}
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static void gvt_cache_remove(struct intel_vgpu *vgpu, gfn_t gfn)
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static void intel_vgpu_unpin_work(struct work_struct *work)
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{
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struct intel_vgpu *vgpu = container_of(work, struct intel_vgpu,
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vdev.unpin_work);
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struct device *dev = mdev_dev(vgpu->vdev.mdev);
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struct gvt_dma *this;
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unsigned long g1;
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int rc;
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unsigned long gfn;
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for (;;) {
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spin_lock(&vgpu->vdev.unpin_lock);
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if (list_empty(&vgpu->vdev.unpin_list)) {
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spin_unlock(&vgpu->vdev.unpin_lock);
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break;
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}
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this = list_first_entry(&vgpu->vdev.unpin_list,
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struct gvt_dma, list);
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list_del(&this->list);
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spin_unlock(&vgpu->vdev.unpin_lock);
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gfn = this->gfn;
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vfio_unpin_pages(dev, &gfn, 1);
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kfree(this);
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}
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}
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static bool gvt_cache_mark_remove(struct intel_vgpu *vgpu, gfn_t gfn)
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{
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struct gvt_dma *this;
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mutex_lock(&vgpu->vdev.cache_lock);
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this = __gvt_cache_find(vgpu, gfn);
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if (!this) {
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mutex_unlock(&vgpu->vdev.cache_lock);
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return;
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return false;
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}
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g1 = gfn;
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gvt_dma_unmap_iova(vgpu, this->iova);
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rc = vfio_unpin_pages(dev, &g1, 1);
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WARN_ON(rc != 1);
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__gvt_cache_remove_entry(vgpu, this);
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/* remove this from rb tree */
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rb_erase(&this->node, &vgpu->vdev.cache);
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mutex_unlock(&vgpu->vdev.cache_lock);
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/* put this to the unpin_list */
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spin_lock(&vgpu->vdev.unpin_lock);
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list_move_tail(&this->list, &vgpu->vdev.unpin_list);
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spin_unlock(&vgpu->vdev.unpin_lock);
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return true;
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}
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static void gvt_cache_init(struct intel_vgpu *vgpu)
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@ -453,6 +481,9 @@ static int intel_vgpu_create(struct kobject *kobj, struct mdev_device *mdev)
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}
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INIT_WORK(&vgpu->vdev.release_work, intel_vgpu_release_work);
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INIT_WORK(&vgpu->vdev.unpin_work, intel_vgpu_unpin_work);
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spin_lock_init(&vgpu->vdev.unpin_lock);
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INIT_LIST_HEAD(&vgpu->vdev.unpin_list);
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vgpu->vdev.mdev = mdev;
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mdev_set_drvdata(mdev, vgpu);
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@ -482,6 +513,7 @@ static int intel_vgpu_iommu_notifier(struct notifier_block *nb,
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struct intel_vgpu *vgpu = container_of(nb,
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struct intel_vgpu,
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vdev.iommu_notifier);
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bool sched_unmap = false;
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if (action == VFIO_IOMMU_NOTIFY_DMA_UNMAP) {
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struct vfio_iommu_type1_dma_unmap *unmap = data;
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@ -491,7 +523,10 @@ static int intel_vgpu_iommu_notifier(struct notifier_block *nb,
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end_gfn = gfn + unmap->size / PAGE_SIZE;
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while (gfn < end_gfn)
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gvt_cache_remove(vgpu, gfn++);
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sched_unmap |= gvt_cache_mark_remove(vgpu, gfn++);
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if (sched_unmap)
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schedule_work(&vgpu->vdev.unpin_work);
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}
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return NOTIFY_OK;
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