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OpenCloudOS-Kernel
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vfio: Simplify vfio_create_group() 

The vfio.group_lock is now only used to serialize vfio_group creation and
destruction, we don't need a micro-optimization of searching, unlocking,
then allocating and searching again. Just hold the lock the whole time.

Grabbed from:
https://lore.kernel.org/kvm/20220922152338.2a2238fe.alex.williamson@redhat.com/

Link: https://lore.kernel.org/r/20221201145535.589687-2-yi.l.liu@intel.com
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Tested-by: Lixiao Yang <lixiao.yang@intel.com>
Tested-by: Yu He <yu.he@intel.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Signed-off-by: Yi Liu <yi.l.liu@intel.com>
This commit is contained in:
Jason Gunthorpe 2022-09-08 15:44:58 -03:00
parent 90337f526c
commit f794eec86c
1 changed files with 10 additions and 23 deletions
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33
drivers/vfio/vfio_main.c
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@ -143,10 +143,12 @@ EXPORT_SYMBOL_GPL(vfio_device_set_open_count);
* Group objects - create, release, get, put, search * Group objects - create, release, get, put, search
*/ */
static struct vfio_group * static struct vfio_group *
__vfio_group_get_from_iommu(struct iommu_group *iommu_group) vfio_group_get_from_iommu(struct iommu_group *iommu_group)
{ {
struct vfio_group *group; struct vfio_group *group;
lockdep_assert_held(&vfio.group_lock);
/* /*
* group->iommu_group from the vfio.group_list cannot be NULL * group->iommu_group from the vfio.group_list cannot be NULL
* under the vfio.group_lock. * under the vfio.group_lock.
@ -160,17 +162,6 @@ __vfio_group_get_from_iommu(struct iommu_group *iommu_group)
return NULL; return NULL;
} }
static struct vfio_group *
vfio_group_get_from_iommu(struct iommu_group *iommu_group)
{
struct vfio_group *group;
mutex_lock(&vfio.group_lock);
group = __vfio_group_get_from_iommu(iommu_group);
mutex_unlock(&vfio.group_lock);
return group;
}
static void vfio_group_release(struct device *dev) static void vfio_group_release(struct device *dev)
{ {
struct vfio_group *group = container_of(dev, struct vfio_group, dev); struct vfio_group *group = container_of(dev, struct vfio_group, dev);
@ -225,6 +216,8 @@ static struct vfio_group *vfio_create_group(struct iommu_group *iommu_group,
struct vfio_group *ret; struct vfio_group *ret;
int err; int err;
lockdep_assert_held(&vfio.group_lock);
group = vfio_group_alloc(iommu_group, type); group = vfio_group_alloc(iommu_group, type);
if (IS_ERR(group)) if (IS_ERR(group))
return group; return group;
@ -237,26 +230,16 @@ static struct vfio_group *vfio_create_group(struct iommu_group *iommu_group,
goto err_put; goto err_put;
} }
mutex_lock(&vfio.group_lock);
/* Did we race creating this group? */
ret = __vfio_group_get_from_iommu(iommu_group);
if (ret)
goto err_unlock;
err = cdev_device_add(&group->cdev, &group->dev); err = cdev_device_add(&group->cdev, &group->dev);
if (err) { if (err) {
ret = ERR_PTR(err); ret = ERR_PTR(err);
goto err_unlock; goto err_put;
} }
list_add(&group->vfio_next, &vfio.group_list); list_add(&group->vfio_next, &vfio.group_list);
mutex_unlock(&vfio.group_lock);
return group; return group;
err_unlock:
mutex_unlock(&vfio.group_lock);
err_put: err_put:
put_device(&group->dev); put_device(&group->dev);
return ret; return ret;
@ -467,7 +450,9 @@ static struct vfio_group *vfio_noiommu_group_alloc(struct device *dev,
if (ret) if (ret)
goto out_put_group; goto out_put_group;
mutex_lock(&vfio.group_lock);
group = vfio_create_group(iommu_group, type); group = vfio_create_group(iommu_group, type);
mutex_unlock(&vfio.group_lock);
if (IS_ERR(group)) { if (IS_ERR(group)) {
ret = PTR_ERR(group); ret = PTR_ERR(group);
goto out_remove_device; goto out_remove_device;
@ -516,9 +501,11 @@ static struct vfio_group *vfio_group_find_or_alloc(struct device *dev)
return ERR_PTR(-EINVAL); return ERR_PTR(-EINVAL);
} }
mutex_lock(&vfio.group_lock);
group = vfio_group_get_from_iommu(iommu_group); group = vfio_group_get_from_iommu(iommu_group);
if (!group) if (!group)
group = vfio_create_group(iommu_group, VFIO_IOMMU); group = vfio_create_group(iommu_group, VFIO_IOMMU);
mutex_unlock(&vfio.group_lock);
/* The vfio_group holds a reference to the iommu_group */ /* The vfio_group holds a reference to the iommu_group */
iommu_group_put(iommu_group); iommu_group_put(iommu_group);