[PATCH v7 04/22] vfio: Accept vfio device file in the KVM facing kAPI

Yi Liu
2023-03-16T12:56:00Z

This makes the vfio file kAPIs to accept 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.

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>
Signed-off-by: Yi Liu <yi.l.liu@intel.com>
---
drivers/vfio/vfio.h | 2 ++
drivers/vfio/vfio_main.c | 18 ++++++++++++++++++
2 files changed, 20 insertions(+)

diff --git a/drivers/vfio/vfio.h b/drivers/vfio/vfio.h
index 56ad127ac618..e4672d91a6f7 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 748bde4d74d9..cb543791b28b 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;
}
@@ -1246,6 +1247,20 @@ bool vfio_file_enforced_coherent(struct file *file)
}
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
@@ -1259,6 +1274,9 @@ void vfio_file_set_kvm(struct file *file, struct kvm *kvm)
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