On 11/25/2025 11:13 AM, Nareshkumar Gollakoti wrote:
> v2:
> - function xe_device_is_vf_enabled has been refactored to
> xe_sriov_pf_has_vfs_enabled and moved to xe_sriov_pf_helper.h.
> - The code now distinctly checks for SR-IOV VF mode and
> SR-IOV PF with VFs enabled.
> - Log messages have been updated to explicitly state the current mode.
> - The function xe_multi_ccs_mode_enabled is moved to xe_device.h
>
> v3: Described missed arg documentation for xe_sriov_pf_has_vfs_enabled
>
> v4:
> - sysfs interface for CCS mode is not initialized
> when operating in SRIOV VF Mode.
> - xe_sriov_pf_has_vfs_enabled() check is sufficient while CCS mode
> enablement.
> - remove unnecessary comments as flow is self explanatory.
>
> v5:(review comments from Michal)
> - Add xe device level CCS mode block with mutex lock and CCS mode state
> - necessesary functions to manage ccs mode state to provide strict mutual
> exclusive support b/w CCS mode & SRIOV VF enabling
>
> v6:
> - Re modeled implementation based on lockdown the PF using custom guard
> supported functions by Michal
>
> Signed-off-by: Nareshkumar Gollakoti <[email protected]>
> ---
> drivers/gpu/drm/xe/xe_gt_ccs_mode.c | 47 ++++++++++++++++++++++++-----
> 1 file changed, 39 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/gpu/drm/xe/xe_gt_ccs_mode.c
> b/drivers/gpu/drm/xe/xe_gt_ccs_mode.c
> index 50fffc9ebf62..495bf517a6d3 100644
> --- a/drivers/gpu/drm/xe/xe_gt_ccs_mode.c
> +++ b/drivers/gpu/drm/xe/xe_gt_ccs_mode.c
> @@ -13,6 +13,7 @@
> #include "xe_gt_sysfs.h"
> #include "xe_mmio.h"
> #include "xe_sriov.h"
> +#include "xe_sriov_pf_helpers.h"
>
> static void __xe_gt_apply_ccs_mode(struct xe_gt *gt, u32 num_engines)
> {
> @@ -108,6 +109,30 @@ ccs_mode_show(struct device *kdev,
> return sysfs_emit(buf, "%u\n", gt->ccs_mode);
> }
>
> +static int xe_gt_prepare_ccs_mode_enabling(struct xe_device *xe,
> + struct xe_gt *gt)
> +{
> + /*
> + * The arm guard is only activated during CCS mode enabling,
> + * and this shuould happen when CCS mode is in default mode.
> + * lockdown arm guard ensures there is no VFS enabling
> + * as CCS mode enabling in progress/enabled.
> + */
> + if (!(gt->ccs_mode > 1))
> + return xe_sriov_pf_arm_guard(xe,
> &xe->sriov.pf.guard_vfs_enabling,
> + true, NULL);
you shouldn't use PF's internals directly, there are public functions:
int xe_sriov_pf_lockdown(struct xe_device *xe);
void xe_sriov_pf_end_lockdown(struct xe_device *xe);
which should be used instead, and just make sure to call them after check:
if (IS_SRIOV_PF(xe))
...
> + return 0;
> +}
> +
> +static void xe_gt_finish_ccs_mode_enabling(struct xe_device *xe,
> + struct xe_gt *gt)
> +{
> + /* disarm the guard, if CCS mode is reverted to default */
> + if (!(gt->ccs_mode > 1))
> + xe_sriov_pf_disarm_guard(xe, &xe->sriov.pf.guard_vfs_enabling,
> + true, NULL);
> +}
> +
> static ssize_t
> ccs_mode_store(struct device *kdev, struct device_attribute *attr,
> const char *buff, size_t count)
> @@ -117,15 +142,13 @@ ccs_mode_store(struct device *kdev, struct
> device_attribute *attr,
> u32 num_engines, num_slices;
> int ret;
>
> - if (IS_SRIOV(xe)) {
> - xe_gt_dbg(gt, "Can't change compute mode when running as %s\n",
> - xe_sriov_mode_to_string(xe_device_sriov_mode(xe)));
> - return -EOPNOTSUPP;
> - }
> + ret = xe_gt_prepare_ccs_mode_enabling(xe, gt);
> + if (ret)
> + return ret;
>
> ret = kstrtou32(buff, 0, &num_engines);
> if (ret)
> - return ret;
> + goto err;
>
> /*
> * Ensure number of engines specified is valid and there is an
> @@ -135,7 +158,8 @@ ccs_mode_store(struct device *kdev, struct
> device_attribute *attr,
> if (!num_engines || num_engines > num_slices || num_slices %
> num_engines) {
> xe_gt_dbg(gt, "Invalid compute config, %d engines %d slices\n",
> num_engines, num_slices);
> - return -EINVAL;
> + ret = -EINVAL;
> + goto err;
> }
>
> /* CCS mode can only be updated when there are no drm clients */
> @@ -143,7 +167,8 @@ ccs_mode_store(struct device *kdev, struct
> device_attribute *attr,
> if (!list_empty(&xe->drm.filelist)) {
> mutex_unlock(&xe->drm.filelist_mutex);
> xe_gt_dbg(gt, "Rejecting compute mode change as there are
> active drm clients\n");
> - return -EBUSY;
> + ret = -EBUSY;
> + goto err;
> }
>
> if (gt->ccs_mode != num_engines) {
> @@ -155,7 +180,13 @@ ccs_mode_store(struct device *kdev, struct
> device_attribute *attr,
>
> mutex_unlock(&xe->drm.filelist_mutex);
>
> + xe_gt_finish_ccs_mode_enabling(xe, gt);
> +
> return count;
> +err:
> + xe_gt_finish_ccs_mode_enabling(xe, gt);
> +
> + return ret;
> }
>
> static DEVICE_ATTR_RW(ccs_mode);
