RADEON_VM_PAGE_VALID
invalid_flags = RADEON_VM_PAGE_VALID | RADEON_VM_PAGE_SYSTEM;
if (!(bo_va->flags & RADEON_VM_PAGE_VALID)) {
hw_flags |= (flags & RADEON_VM_PAGE_VALID) ? R600_PTE_VALID : 0;
bo_va->flags &= ~RADEON_VM_PAGE_VALID;
bo_va->flags |= RADEON_VM_PAGE_VALID;