Re: [PATCH 1/9] vfio: Make vfio_(un)register_notifier accept a vfio_device

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On 4/12/22 11:53 AM, Jason Gunthorpe wrote:

All callers have a struct vfio_device trivially available, pass it in
directly and avoid calling the expensive vfio_group_get_from_dev().

To support the unconverted kvmgt mdev driver add
mdev_legacy_get_vfio_device() which will return the vfio_device pointer
vfio_mdev.c puts in the drv_data.

Signed-off-by: Jason Gunthorpe <jgg@xxxxxxxxxx>
---
  drivers/gpu/drm/i915/gvt/kvmgt.c  | 15 +++++++++------
  drivers/s390/cio/vfio_ccw_ops.c   |  7 +++----
  drivers/s390/crypto/vfio_ap_ops.c | 14 +++++++-------
  drivers/vfio/mdev/vfio_mdev.c     | 12 ++++++++++++
  drivers/vfio/vfio.c               | 25 +++++++------------------
  include/linux/mdev.h              |  1 +
  include/linux/vfio.h              |  4 ++--
  7 files changed, 41 insertions(+), 37 deletions(-)

diff --git a/drivers/gpu/drm/i915/gvt/kvmgt.c b/drivers/gpu/drm/i915/gvt/kvmgt.c
index 057ec449010458..bb59d21cf898ab 100644
--- a/drivers/gpu/drm/i915/gvt/kvmgt.c
+++ b/drivers/gpu/drm/i915/gvt/kvmgt.c
@@ -904,6 +904,7 @@ static int intel_vgpu_group_notifier(struct notifier_block *nb,
static int intel_vgpu_open_device(struct mdev_device *mdev) 
  {
+	struct vfio_device *vfio_dev = mdev_legacy_get_vfio_device(mdev);
  	struct intel_vgpu *vgpu = mdev_get_drvdata(mdev);
  	struct kvmgt_vdev *vdev = kvmgt_vdev(vgpu);
  	unsigned long events;
@@ -914,7 +915,7 @@ static int intel_vgpu_open_device(struct mdev_device *mdev)
  	vdev->group_notifier.notifier_call = intel_vgpu_group_notifier;
events = VFIO_IOMMU_NOTIFY_DMA_UNMAP; 
-	ret = vfio_register_notifier(mdev_dev(mdev), VFIO_IOMMU_NOTIFY, &events,
+	ret = vfio_register_notifier(vfio_dev, VFIO_IOMMU_NOTIFY, &events,
  				&vdev->iommu_notifier);
  	if (ret != 0) {
  		gvt_vgpu_err("vfio_register_notifier for iommu failed: %d\n",
@@ -923,7 +924,7 @@ static int intel_vgpu_open_device(struct mdev_device *mdev)
  	}
events = VFIO_GROUP_NOTIFY_SET_KVM; 
-	ret = vfio_register_notifier(mdev_dev(mdev), VFIO_GROUP_NOTIFY, &events,
+	ret = vfio_register_notifier(vfio_dev, VFIO_GROUP_NOTIFY, &events,
  				&vdev->group_notifier);
  	if (ret != 0) {
  		gvt_vgpu_err("vfio_register_notifier for group failed: %d\n",
@@ -961,11 +962,11 @@ static int intel_vgpu_open_device(struct mdev_device *mdev)
  	vdev->vfio_group = NULL;
undo_register: 
-	vfio_unregister_notifier(mdev_dev(mdev), VFIO_GROUP_NOTIFY,
+	vfio_unregister_notifier(vfio_dev, VFIO_GROUP_NOTIFY,
  					&vdev->group_notifier);
undo_iommu: 
-	vfio_unregister_notifier(mdev_dev(mdev), VFIO_IOMMU_NOTIFY,
+	vfio_unregister_notifier(vfio_dev, VFIO_IOMMU_NOTIFY,
  					&vdev->iommu_notifier);
  out:
  	return ret;
@@ -988,6 +989,7 @@ static void __intel_vgpu_release(struct intel_vgpu *vgpu)
  	struct kvmgt_vdev *vdev = kvmgt_vdev(vgpu);
  	struct drm_i915_private *i915 = vgpu->gvt->gt->i915;
  	struct kvmgt_guest_info *info;
+	struct vfio_device *vfio_dev;
  	int ret;
if (!handle_valid(vgpu->handle)) 
@@ -998,12 +1000,13 @@ static void __intel_vgpu_release(struct intel_vgpu *vgpu)
intel_gvt_ops->vgpu_release(vgpu); - ret = vfio_unregister_notifier(mdev_dev(vdev->mdev), VFIO_IOMMU_NOTIFY, 
+	vfio_dev = mdev_legacy_get_vfio_device(vdev->mdev);
+	ret = vfio_unregister_notifier(vfio_dev, VFIO_IOMMU_NOTIFY,
  					&vdev->iommu_notifier);
  	drm_WARN(&i915->drm, ret,
  		 "vfio_unregister_notifier for iommu failed: %d\n", ret);
- ret = vfio_unregister_notifier(mdev_dev(vdev->mdev), VFIO_GROUP_NOTIFY, 
+	ret = vfio_unregister_notifier(vfio_dev, VFIO_GROUP_NOTIFY,
  					&vdev->group_notifier);
  	drm_WARN(&i915->drm, ret,
  		 "vfio_unregister_notifier for group failed: %d\n", ret);
diff --git a/drivers/s390/cio/vfio_ccw_ops.c b/drivers/s390/cio/vfio_ccw_ops.c
index d8589afac272f1..e1ce24d8fb2555 100644
--- a/drivers/s390/cio/vfio_ccw_ops.c
+++ b/drivers/s390/cio/vfio_ccw_ops.c
@@ -183,7 +183,7 @@ static int vfio_ccw_mdev_open_device(struct vfio_device *vdev)
private->nb.notifier_call = vfio_ccw_mdev_notifier; - ret = vfio_register_notifier(vdev->dev, VFIO_IOMMU_NOTIFY, 
+	ret = vfio_register_notifier(vdev, VFIO_IOMMU_NOTIFY,
  				     &events, &private->nb);
  	if (ret)
  		return ret;
@@ -204,8 +204,7 @@ static int vfio_ccw_mdev_open_device(struct vfio_device *vdev)
out_unregister: 
  	vfio_ccw_unregister_dev_regions(private);
-	vfio_unregister_notifier(vdev->dev, VFIO_IOMMU_NOTIFY,
-				 &private->nb);
+	vfio_unregister_notifier(vdev, VFIO_IOMMU_NOTIFY, &private->nb);
  	return ret;
  }
@@ -223,7 +222,7 @@ static void vfio_ccw_mdev_close_device(struct vfio_device *vdev) cp_free(&private->cp); 
  	vfio_ccw_unregister_dev_regions(private);
-	vfio_unregister_notifier(vdev->dev, VFIO_IOMMU_NOTIFY, &private->nb);
+	vfio_unregister_notifier(vdev, VFIO_IOMMU_NOTIFY, &private->nb);
  }
static ssize_t vfio_ccw_mdev_read_io_region(struct vfio_ccw_private *private, 
diff --git a/drivers/s390/crypto/vfio_ap_ops.c b/drivers/s390/crypto/vfio_ap_ops.c
index 6e08d04b605d6e..69768061cd7bd9 100644
--- a/drivers/s390/crypto/vfio_ap_ops.c
+++ b/drivers/s390/crypto/vfio_ap_ops.c
@@ -1406,21 +1406,21 @@ static int vfio_ap_mdev_open_device(struct vfio_device *vdev)
  	matrix_mdev->group_notifier.notifier_call = vfio_ap_mdev_group_notifier;
  	events = VFIO_GROUP_NOTIFY_SET_KVM;
- ret = vfio_register_notifier(vdev->dev, VFIO_GROUP_NOTIFY, 
-				     &events, &matrix_mdev->group_notifier);
+	ret = vfio_register_notifier(vdev, VFIO_GROUP_NOTIFY, &events,
+				     &matrix_mdev->group_notifier);
  	if (ret)
  		return ret;
matrix_mdev->iommu_notifier.notifier_call = vfio_ap_mdev_iommu_notifier; 
  	events = VFIO_IOMMU_NOTIFY_DMA_UNMAP;
-	ret = vfio_register_notifier(vdev->dev, VFIO_IOMMU_NOTIFY,
-				     &events, &matrix_mdev->iommu_notifier);
+	ret = vfio_register_notifier(vdev, VFIO_IOMMU_NOTIFY, &events,
+				     &matrix_mdev->iommu_notifier);
  	if (ret)
  		goto out_unregister_group;
  	return 0;
out_unregister_group: 
-	vfio_unregister_notifier(vdev->dev, VFIO_GROUP_NOTIFY,
+	vfio_unregister_notifier(vdev, VFIO_GROUP_NOTIFY,
  				 &matrix_mdev->group_notifier);
  	return ret;
  }
@@ -1430,9 +1430,9 @@ static void vfio_ap_mdev_close_device(struct vfio_device *vdev)
  	struct ap_matrix_mdev *matrix_mdev =
  		container_of(vdev, struct ap_matrix_mdev, vdev);
- vfio_unregister_notifier(vdev->dev, VFIO_IOMMU_NOTIFY, 
+	vfio_unregister_notifier(vdev, VFIO_IOMMU_NOTIFY,
  				 &matrix_mdev->iommu_notifier);
-	vfio_unregister_notifier(vdev->dev, VFIO_GROUP_NOTIFY,
+	vfio_unregister_notifier(vdev, VFIO_GROUP_NOTIFY,
  				 &matrix_mdev->group_notifier);
  	vfio_ap_mdev_unset_kvm(matrix_mdev);
  }
diff --git a/drivers/vfio/mdev/vfio_mdev.c b/drivers/vfio/mdev/vfio_mdev.c
index a90e24b0c851d3..91605c1e8c8f94 100644
--- a/drivers/vfio/mdev/vfio_mdev.c
+++ b/drivers/vfio/mdev/vfio_mdev.c
@@ -17,6 +17,18 @@
#include "mdev_private.h" +/* 
+ * Return the struct vfio_device for the mdev when using the legacy
+ * vfio_mdev_dev_ops path. No new callers to this function should be added.
+ */
+struct vfio_device *mdev_legacy_get_vfio_device(struct mdev_device *mdev)
+{
+	if (WARN_ON(mdev->dev.driver != &vfio_mdev_driver.driver))
+		return NULL;
+	return dev_get_drvdata(&mdev->dev);
+}
+EXPORT_SYMBOL_GPL(mdev_legacy_get_vfio_device);
+
  static int vfio_mdev_open_device(struct vfio_device *core_vdev)
  {
  	struct mdev_device *mdev = to_mdev_device(core_vdev->dev);
diff --git a/drivers/vfio/vfio.c b/drivers/vfio/vfio.c
index a4555014bd1e72..8a5c46aa2bef61 100644
--- a/drivers/vfio/vfio.c
+++ b/drivers/vfio/vfio.c
@@ -2484,19 +2484,15 @@ static int vfio_unregister_group_notifier(struct vfio_group *group,
  	return ret;
  }
-int vfio_register_notifier(struct device *dev, enum vfio_notify_type type, 
+int vfio_register_notifier(struct vfio_device *dev, enum vfio_notify_type type,
  			   unsigned long *events, struct notifier_block *nb)
  {
-	struct vfio_group *group;
+	struct vfio_group *group = dev->group;


Is there a guarantee that dev != NULL? The original code below checks
the value of dev, so why is that check eliminated here?


  	int ret;
- if (!dev || !nb || !events || (*events == 0)) 
+	if (!nb || !events || (*events == 0))
  		return -EINVAL;
- group = vfio_group_get_from_dev(dev); 
-	if (!group)
-		return -ENODEV;
-
  	switch (type) {
  	case VFIO_IOMMU_NOTIFY:
  		ret = vfio_register_iommu_notifier(group, events, nb);
@@ -2507,25 +2503,20 @@ int vfio_register_notifier(struct device *dev, enum vfio_notify_type type,
  	default:
  		ret = -EINVAL;
  	}
-
-	vfio_group_put(group);
  	return ret;
  }
  EXPORT_SYMBOL(vfio_register_notifier);
-int vfio_unregister_notifier(struct device *dev, enum vfio_notify_type type, 
+int vfio_unregister_notifier(struct vfio_device *dev,
+			     enum vfio_notify_type type,
  			     struct notifier_block *nb)
  {
-	struct vfio_group *group;
+	struct vfio_group *group = dev->group;


Same comment as above, not NULL check here.


  	int ret;
- if (!dev || !nb) 
+	if (!nb)
  		return -EINVAL;
- group = vfio_group_get_from_dev(dev); 
-	if (!group)
-		return -ENODEV;
-
  	switch (type) {
  	case VFIO_IOMMU_NOTIFY:
  		ret = vfio_unregister_iommu_notifier(group, nb);
@@ -2536,8 +2527,6 @@ int vfio_unregister_notifier(struct device *dev, enum vfio_notify_type type,
  	default:
  		ret = -EINVAL;
  	}
-
-	vfio_group_put(group);
  	return ret;
  }
  EXPORT_SYMBOL(vfio_unregister_notifier);
diff --git a/include/linux/mdev.h b/include/linux/mdev.h
index 15d03f6532d073..67d07220a28f29 100644
--- a/include/linux/mdev.h
+++ b/include/linux/mdev.h
@@ -29,6 +29,7 @@ static inline struct mdev_device *to_mdev_device(struct device *dev)
  unsigned int mdev_get_type_group_id(struct mdev_device *mdev);
  unsigned int mtype_get_type_group_id(struct mdev_type *mtype);
  struct device *mtype_get_parent_dev(struct mdev_type *mtype);
+struct vfio_device *mdev_legacy_get_vfio_device(struct mdev_device *mdev);
/** 
   * struct mdev_parent_ops - Structure to be registered for each parent device to
diff --git a/include/linux/vfio.h b/include/linux/vfio.h
index 66dda06ec42d1b..748ec0e0293aea 100644
--- a/include/linux/vfio.h
+++ b/include/linux/vfio.h
@@ -178,11 +178,11 @@ enum vfio_notify_type {
  /* events for VFIO_GROUP_NOTIFY */
  #define VFIO_GROUP_NOTIFY_SET_KVM	BIT(0)
-extern int vfio_register_notifier(struct device *dev, 
+extern int vfio_register_notifier(struct vfio_device *dev,
  				  enum vfio_notify_type type,
  				  unsigned long *required_events,
  				  struct notifier_block *nb);
-extern int vfio_unregister_notifier(struct device *dev,
+extern int vfio_unregister_notifier(struct vfio_device *dev,
  				    enum vfio_notify_type type,
  				    struct notifier_block *nb);
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