drm/xe/pxp/uapi: Add API to mark a BO as using PXP

The driver needs to know if a BO is encrypted with PXP to enable the
display decryption at flip time.
Furthermore, we want to keep track of the status of the encryption and
reject any operation that involves a BO that is encrypted using an old
key. There are two points in time where such checks can kick in:

1 - at VM bind time, all operations except for unmapping will be
    rejected if the key used to encrypt the BO is no longer valid. This
    check is opt-in via a new VM_BIND flag, to avoid a scenario where a
    malicious app purposely shares an invalid BO with a non-PXP aware
    app (such as a compositor). If the VM_BIND was failed, the
    compositor would be unable to display anything at all. Allowing the
    bind to go through means that output still works, it just displays
    garbage data within the bounds of the illegal BO.

2 - at job submission time, if the queue is marked as using PXP, all
    objects bound to the VM will be checked and the submission will be
    rejected if any of them was encrypted with a key that is no longer
    valid.

Note that there is no risk of leaking the encrypted data if a user does
not opt-in to those checks; the only consequence is that the user will
not realize that the encryption key is changed and that the data is no
longer valid.

v2: Better commnnts and descriptions (John), rebase

v3: Properly return the result of key_assign up the stack, do not use
xe_bo in display headers (Jani)

v4: improve key_instance variable documentation (John)

Signed-off-by: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Cc: Matthew Brost <matthew.brost@intel.com>
Cc: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Cc: John Harrison <John.C.Harrison@Intel.com>
Cc: Jani Nikula <jani.nikula@intel.com>
Reviewed-by: John Harrison <John.C.Harrison@Intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20250129174140.948829-11-daniele.ceraolospurio@intel.com

1 files changed, 19 insertions, 0 deletions

diff --git a/include/uapi/drm/xe_drm.h b/include/uapi/drm/xe_drm.h
index 112fd27f3c75..892f54d3aa09 100644
--- a/include/uapi/drm/xe_drm.h
+++ b/include/uapi/drm/xe_drm.h
@@ -778,8 +778,23 @@ struct drm_xe_device_query {
  *  - %DRM_XE_GEM_CPU_CACHING_WC - Allocate the pages as write-combined. This
  *    is uncached. Scanout surfaces should likely use this. All objects
  *    that can be placed in VRAM must use this.
+ *
+ * This ioctl supports setting the following properties via the
+ * %DRM_XE_GEM_CREATE_EXTENSION_SET_PROPERTY extension, which uses the
+ * generic @drm_xe_ext_set_property struct:
+ *
+ *  - %DRM_XE_GEM_CREATE_SET_PROPERTY_PXP_TYPE - set the type of PXP session
+ *    this object will be used with. Valid values are listed in enum
+ *    drm_xe_pxp_session_type. %DRM_XE_PXP_TYPE_NONE is the default behavior, so
+ *    there is no need to explicitly set that. Objects used with session of type
+ *    %DRM_XE_PXP_TYPE_HWDRM will be marked as invalid if a PXP invalidation
+ *    event occurs after their creation. Attempting to flip an invalid object
+ *    will cause a black frame to be displayed instead. Submissions with invalid
+ *    objects mapped in the VM will be rejected.
  */
 struct drm_xe_gem_create {
+#define DRM_XE_GEM_CREATE_EXTENSION_SET_PROPERTY	0
+#define   DRM_XE_GEM_CREATE_SET_PROPERTY_PXP_TYPE	0
 	/** @extensions: Pointer to the first extension struct, if any */
 	__u64 extensions;
 
@@ -968,6 +983,9 @@ struct drm_xe_vm_destroy {
  *    will only be valid for DRM_XE_VM_BIND_OP_MAP operations, the BO
  *    handle MBZ, and the BO offset MBZ. This flag is intended to
  *    implement VK sparse bindings.
+ *  - %DRM_XE_VM_BIND_FLAG_CHECK_PXP - If the object is encrypted via PXP,
+ *    reject the binding if the encryption key is no longer valid. This
+ *    flag has no effect on BOs that are not marked as using PXP.
  */
 struct drm_xe_vm_bind_op {
 	/** @extensions: Pointer to the first extension struct, if any */
@@ -1058,6 +1076,7 @@ struct drm_xe_vm_bind_op {
 #define DRM_XE_VM_BIND_FLAG_IMMEDIATE	(1 << 1)
 #define DRM_XE_VM_BIND_FLAG_NULL	(1 << 2)
 #define DRM_XE_VM_BIND_FLAG_DUMPABLE	(1 << 3)
+#define DRM_XE_VM_BIND_FLAG_CHECK_PXP	(1 << 4)
 	/** @flags: Bind flags */
 	__u32 flags;