drm/amdgpu: keep PRT mappings off the vm_bo state lists

A PRT/sparse mapping has no backing BO, so its bo_va->base.bo is NULL.
amdgpu_vm_bo_base_init() deliberately keeps such a bo_va off the vm_bo
state lists, but the tail of amdgpu_vm_bo_update() unconditionally called
amdgpu_vm_bo_idle() for the !always_valid case, putting the NULL-bo PRT
bo_va onto the individual.idle list.

On a GPU reset amdgpu_vm_bo_reset_state_machine() moves individual.idle
to individual.needs_update with moved=true, and amdgpu_vm_handle_moved()
then dereferences bo_va->base.bo to read its reservation object,
crashing on the NULL bo (e.g. the userq eviction restore worker running
during a reset while a user queue is torn down):

  BUG: kernel NULL pointer dereference, address: 0000000000000158
  RIP: 0010:amdgpu_vm_handle_moved+0x17a/0x200 [amdgpu]
  Call Trace:
   amdgpu_userq_vm_validate_and_restore_queue+0x2ce/0x920 [amdgpu]
   amdgpu_userq_restore_worker+0xce/0x210 [amdgpu]

Skip amdgpu_vm_bo_idle() when bo is NULL so a PRT mapping never lands on
a state list in the first place, and refresh the PRT page tables
explicitly in the userq restore path (as the CS path already does) so
sparse mappings survive a VRAM-lost reset. Because the PRT bo_va is off
the state lists, its PTE update fence lands in prt_va->last_pt_update
rather than vm->last_update, so wait on it explicitly before restarting
the queues (mirroring how the CS path syncs that fence).

v2:
 - keep the PRT bo_va off the vm_bo state lists instead of NULL-guarding
   bo inside amdgpu_vm_handle_moved(); a PRT mapping should never be on
   the moved list in the first place (Christian)

v3:
 - the PRT PTEs are updated separately, so their fence is in
   prt_va->last_pt_update, not vm->last_update; wait on it in the userq
   restore path before restarting queues, otherwise the queues could
   restart before the sparse PTEs are written (Christian)

Suggested-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Jesse Zhang <Jesse.Zhang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

0 files changed, 0 insertions, 0 deletions