[Intel-xe] [PATCH 4/4] drm/xe/vm: Fix ASID XA usage

[Ohad Sharabi]

On 22/11/2023 13:03, Thomas Hellström wrote:
> xa_alloc_cyclic() returns 1 on successful allocation, if wrapping occurs,
> but the code incorrectly treats that as an error. Fix that.
> Also, xa_alloc_cyclic() requires xa_init_flags(..., XA_FLAGS_ALLOC), so
> fix that, and assuming we don't want a zero ASID, instead of using
> XA_FLAGS_ALLOC1, adjust the xa limits at alloc_cyclic time.
>
> Suggested-by: Ohad Sharabi <osharabi at habana.ai>
> Link: https://gitlab.freedesktop.org/drm/xe/kernel/-/issues/946
> Signed-off-by: Thomas Hellström <thomas.hellstrom at linux.intel.com>
Reviewed-by: Ohad Sharabi <osharavi at habana.ai>
> ---
>   drivers/gpu/drm/xe/xe_device.c | 2 +-
>   drivers/gpu/drm/xe/xe_vm.c     | 5 +++--
>   2 files changed, 4 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/gpu/drm/xe/xe_device.c b/drivers/gpu/drm/xe/xe_device.c
> index 8be765adf702..a67aaa15b4ae 100644
> --- a/drivers/gpu/drm/xe/xe_device.c
> +++ b/drivers/gpu/drm/xe/xe_device.c
> @@ -230,7 +230,7 @@ struct xe_device *xe_device_create(struct pci_dev *pdev,
>       init_waitqueue_head(&xe->ufence_wq);
>
>       drmm_mutex_init(&xe->drm, &xe->usm.lock);
> -     xa_init_flags(&xe->usm.asid_to_vm, XA_FLAGS_ALLOC1);
> +     xa_init_flags(&xe->usm.asid_to_vm, XA_FLAGS_ALLOC);
>
>       drmm_mutex_init(&xe->drm, &xe->persistent_engines.lock);
>       INIT_LIST_HEAD(&xe->persistent_engines.list);
> diff --git a/drivers/gpu/drm/xe/xe_vm.c b/drivers/gpu/drm/xe/xe_vm.c
> index b39c6f43f01f..85b9d6f864ec 100644
> --- a/drivers/gpu/drm/xe/xe_vm.c
> +++ b/drivers/gpu/drm/xe/xe_vm.c
> @@ -1994,13 +1994,14 @@ int xe_vm_create_ioctl(struct drm_device *dev, void *data,
>       if (xe->info.has_asid) {
>               mutex_lock(&xe->usm.lock);
>               err = xa_alloc_cyclic(&xe->usm.asid_to_vm, &asid, vm,
> -                                   XA_LIMIT(0, XE_MAX_ASID - 1),
> +                                   XA_LIMIT(1, XE_MAX_ASID - 1),
>                                     &xe->usm.next_asid, GFP_KERNEL);
>               mutex_unlock(&xe->usm.lock);
> -             if (err) {
> +             if (err < 0) {
>                       xe_vm_close_and_put(vm);
>                       return err;
>               }
> +             err = 0;
>               vm->usm.asid = asid;
>       }
>