[RFC PATCH v2 4/7] iommufd: Associate kvm pointer to iommufd ctx

[Shameer Kolothum]

Introduce an API to set the KVM pointer to the iommufd ctx
and set the same when a vfio dev is bind to iommufd.

Signed-off-by: Shameer Kolothum <shameerali.kolothum.thodi at huawei.com>
---
 drivers/iommu/iommufd/iommufd_private.h |  3 +++
 drivers/iommu/iommufd/main.c            | 14 ++++++++++++++
 drivers/vfio/device_cdev.c              |  3 +++
 include/linux/iommufd.h                 |  7 +++++++
 4 files changed, 27 insertions(+)

diff --git a/drivers/iommu/iommufd/iommufd_private.h b/drivers/iommu/iommufd/iommufd_private.h
index 991f864d1f9b..28ede82bb1a6 100644
--- a/drivers/iommu/iommufd/iommufd_private.h
+++ b/drivers/iommu/iommufd/iommufd_private.h
@@ -16,6 +16,7 @@ struct iommu_domain;
 struct iommu_group;
 struct iommu_option;
 struct iommufd_device;
+struct kvm;
 
 struct iommufd_ctx {
 	struct file *file;
@@ -27,6 +28,8 @@ struct iommufd_ctx {
 	/* Compatibility with VFIO no iommu */
 	u8 no_iommu_mode;
 	struct iommufd_ioas *vfio_ioas;
+	/* Associated KVM pointer */
+	struct kvm *kvm;
 };
 
 /*
diff --git a/drivers/iommu/iommufd/main.c b/drivers/iommu/iommufd/main.c
index 39b32932c61e..28272510fba4 100644
--- a/drivers/iommu/iommufd/main.c
+++ b/drivers/iommu/iommufd/main.c
@@ -495,6 +495,20 @@ void iommufd_ctx_put(struct iommufd_ctx *ictx)
 }
 EXPORT_SYMBOL_NS_GPL(iommufd_ctx_put, IOMMUFD);
 
+/**
+ * iommufd_ctx_set_kvm - Called to set a KVM pointer to iommufd context
+ * @ictx: Context to operate on
+ * @kvm: KVM pointer with a reference taken using kvm_get_kvm_safe()
+ */
+void iommufd_ctx_set_kvm(struct iommufd_ctx *ictx, struct kvm *kvm)
+{
+	xa_lock(&ictx->objects);
+	if (!ictx->kvm)
+		ictx->kvm = kvm;
+	xa_unlock(&ictx->objects);
+}
+EXPORT_SYMBOL_NS_GPL(iommufd_ctx_set_kvm, IOMMUFD);
+
 static const struct iommufd_object_ops iommufd_object_ops[] = {
 	[IOMMUFD_OBJ_ACCESS] = {
 		.destroy = iommufd_access_destroy_object,
diff --git a/drivers/vfio/device_cdev.c b/drivers/vfio/device_cdev.c
index e75da0a70d1f..e75e96fb57cb 100644
--- a/drivers/vfio/device_cdev.c
+++ b/drivers/vfio/device_cdev.c
@@ -101,6 +101,9 @@ long vfio_df_ioctl_bind_iommufd(struct vfio_device_file *df,
 	 */
 	vfio_df_get_kvm_safe(df);
 
+	if (df->kvm)
+		iommufd_ctx_set_kvm(df->iommufd, df->kvm);
+
 	ret = vfio_df_open(df);
 	if (ret)
 		goto out_put_kvm;
diff --git a/include/linux/iommufd.h b/include/linux/iommufd.h
index ffc3a949f837..7408b620d0b8 100644
--- a/include/linux/iommufd.h
+++ b/include/linux/iommufd.h
@@ -17,6 +17,7 @@ struct iommufd_ctx;
 struct iommufd_access;
 struct file;
 struct iommu_group;
+struct kvm;
 
 struct iommufd_device *iommufd_device_bind(struct iommufd_ctx *ictx,
 					   struct device *dev, u32 *id);
@@ -59,6 +60,7 @@ struct iommufd_ctx *iommufd_ctx_from_file(struct file *file);
 struct iommufd_ctx *iommufd_ctx_from_fd(int fd);
 void iommufd_ctx_put(struct iommufd_ctx *ictx);
 bool iommufd_ctx_has_group(struct iommufd_ctx *ictx, struct iommu_group *group);
+void iommufd_ctx_set_kvm(struct iommufd_ctx *ictx, struct kvm *kvm);
 
 int iommufd_access_pin_pages(struct iommufd_access *access, unsigned long iova,
 			     unsigned long length, struct page **out_pages,
@@ -80,6 +82,11 @@ static inline void iommufd_ctx_put(struct iommufd_ctx *ictx)
 {
 }
 
+static inline void iommufd_ctx_set_kvm(struct iommufd_ctx *ictx,
+				       struct kvm *kvm)
+{
+}
+
 static inline int iommufd_access_pin_pages(struct iommufd_access *access,
 					   unsigned long iova,
 					   unsigned long length,
-- 
2.34.1