[Intel-gfx] [PATCH v13 03/22] vfio: Accept vfio device file in the KVM facing kAPI

[Yi Liu]

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.t...@intel.com>
Reviewed-by: Jason Gunthorpe <j...@nvidia.com>
Tested-by: Terrence Xu <terrence...@intel.com>
Tested-by: Nicolin Chen <nicol...@nvidia.com>
Tested-by: Matthew Rosato <mjros...@linux.ibm.com>
Tested-by: Yanting Jiang <yanting.ji...@intel.com>
Tested-by: Shameer Kolothum <shameerali.kolothum.th...@huawei.com>
Signed-off-by: Yi Liu <yi.l....@intel.com>
---
 drivers/vfio/vfio.h      |  3 +++
 drivers/vfio/vfio_main.c | 36 +++++++++++++++++++++++++++++++++++-
 2 files changed, 38 insertions(+), 1 deletion(-)

diff --git a/drivers/vfio/vfio.h b/drivers/vfio/vfio.h
index b1e327a85a32..332528af0846 100644
--- a/drivers/vfio/vfio.h
+++ b/drivers/vfio/vfio.h
@@ -18,6 +18,9 @@ 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 4665791aa2eb..8ef9210ad2aa 100644
--- a/drivers/vfio/vfio_main.c
+++ b/drivers/vfio/vfio_main.c
@@ -429,6 +429,7 @@ vfio_allocate_device_file(struct vfio_device *device)
                return ERR_PTR(-ENOMEM);
 
        df->device = device;
+       spin_lock_init(&df->kvm_ref_lock);
 
        return df;
 }
@@ -1190,13 +1191,23 @@ 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);
 
@@ -1211,16 +1222,36 @@ EXPORT_SYMBOL_GPL(vfio_file_is_valid);
  */
 bool vfio_file_enforced_coherent(struct file *file)
 {
+       struct vfio_device *device;
        struct vfio_group *group;
 
        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
@@ -1236,6 +1267,9 @@ 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