[PATCH v6 03/24] vfio: Accept vfio device file in the KVM facing kAPI

Yi Liu
2023-03-08T13:30:49Z

This makes the vfio file kAPIs to accepte vfio device files, also a
preparation for vfio device cdev support.

For the kvm set with vfio device file, kvm pointer is stored in struct
vfio_device_file, and use kvm_ref_lock to protect kvm set and kvm
pointer usage within VFIO. This kvm pointer will be set to vfio_device
after device file is bound to iommufd in the cdev path.

Signed-off-by: Yi Liu <yi.l.liu@intel.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Tested-by: Terrence Xu <terrence.xu@intel.com>
Tested-by: Nicolin Chen <nicolinc@nvidia.com>
Tested-by: Matthew Rosato <mjrosato@linux.ibm.com>
---
drivers/vfio/vfio.h | 2 ++
drivers/vfio/vfio_main.c | 42 +++++++++++++++++++++++++++++++++++++---
2 files changed, 41 insertions(+), 3 deletions(-)

diff --git a/drivers/vfio/vfio.h b/drivers/vfio/vfio.h
index b1e327a85a32..69e1a0692b06 100644
--- a/drivers/vfio/vfio.h
+++ b/drivers/vfio/vfio.h
@@ -18,6 +18,8 @@ struct vfio_container;

struct vfio_device_file {
struct vfio_device *device;
+ spinlock_t kvm_ref_lock; /* protect kvm field */
+ struct kvm *kvm;
};

void vfio_device_put_registration(struct vfio_device *device);
diff --git a/drivers/vfio/vfio_main.c b/drivers/vfio/vfio_main.c
index edadfac9be49..03d5b2979f79 100644
--- a/drivers/vfio/vfio_main.c
+++ b/drivers/vfio/vfio_main.c
@@ -414,6 +414,7 @@ vfio_allocate_device_file(struct vfio_device *device)
return ERR_PTR(-ENOMEM);

df->device = device;
+ spin_lock_init(&df->kvm_ref_lock);

return df;
}
@@ -1175,13 +1176,23 @@ const struct file_operations vfio_device_fops = {
.mmap = vfio_device_fops_mmap,
};

+static struct vfio_device *vfio_device_from_file(struct file *file)
+{
+ struct vfio_device_file *df = file->private_data;
+
+ if (file->f_op != &vfio_device_fops)
+ return NULL;
+ return df->device;
+}
+
/**
* vfio_file_is_valid - True if the file is valid vfio file
* @file: VFIO group file or VFIO device file
*/
bool vfio_file_is_valid(struct file *file)
{
- return vfio_group_from_file(file);
+ return vfio_group_from_file(file) ||
+ vfio_device_from_file(file);
}
EXPORT_SYMBOL_GPL(vfio_file_is_valid);

@@ -1196,15 +1207,36 @@ EXPORT_SYMBOL_GPL(vfio_file_is_valid);
*/
bool vfio_file_enforced_coherent(struct file *file)
{
- struct vfio_group *group = vfio_group_from_file(file);
+ struct vfio_group *group;
+ struct vfio_device *device;

+ group = vfio_group_from_file(file);
if (group)
return vfio_group_enforced_coherent(group);

+ device = vfio_device_from_file(file);
+ if (device)
+ return device_iommu_capable(device->dev,
+ IOMMU_CAP_ENFORCE_CACHE_COHERENCY);
+
return true;
}
EXPORT_SYMBOL_GPL(vfio_file_enforced_coherent);

+static void vfio_device_file_set_kvm(struct file *file, struct kvm *kvm)
+{
+ struct vfio_device_file *df = file->private_data;
+
+ /*
+ * The kvm is first recorded in the vfio_device_file, and will
+ * be propagated to vfio_device::kvm when the file is bound to
+ * iommufd successfully in the vfio device cdev path.
+ */
+ spin_lock(&df->kvm_ref_lock);
+ df->kvm = kvm;
+ spin_unlock(&df->kvm_ref_lock);
+}
+
/**
* vfio_file_set_kvm - Link a kvm with VFIO drivers
* @file: VFIO group file or VFIO device file
@@ -1213,10 +1245,14 @@ EXPORT_SYMBOL_GPL(vfio_file_enforced_coherent);
*/
void vfio_file_set_kvm(struct file *file, struct kvm *kvm)
{
- struct vfio_group *group = vfio_group_from_file(file);
+ struct vfio_group *group;

+ group = vfio_group_from_file(file);
if (group)
vfio_group_set_kvm(group, kvm);
+
+ if (vfio_device_from_file(file))
+ vfio_device_file_set_kvm(file, kvm);
}
EXPORT_SYMBOL_GPL(vfio_file_set_kvm);

--
2.34.1