From 9b5e995e61290741b0e2b70fc631cc591e21d499 Mon Sep 17 00:00:00 2001 From: Nareshkumar Gollakoti Date: Mon, 2 Feb 2026 22:38:13 +0530 Subject: [PATCH] drm/xe: Mutual exclusivity between CCS-mode and PF Due to SLA agreement between PF and VFs, currently we block CCS mode changes if driver is running as PF, even if there are no VFs enabled yet. Use lockdown mechanism provided by the PF to relax that limitation and still enforce above VFs related requirements. Reviewed-by: Michal Wajdeczko Signed-off-by: Nareshkumar Gollakoti Signed-off-by: Michal Wajdeczko Link: https://patch.msgid.link/20260202170810.1393147-6-naresh.kumar.g@intel.com --- drivers/gpu/drm/xe/xe_gt_ccs_mode.c | 42 +++++++++++++++++++---------- 1 file changed, 28 insertions(+), 14 deletions(-) diff --git a/drivers/gpu/drm/xe/xe_gt_ccs_mode.c b/drivers/gpu/drm/xe/xe_gt_ccs_mode.c index fe944687728c..b35be36b0eaa 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.h" static void __xe_gt_apply_ccs_mode(struct xe_gt *gt, u32 num_engines) { @@ -88,6 +89,11 @@ void xe_gt_apply_ccs_mode(struct xe_gt *gt) __xe_gt_apply_ccs_mode(gt, gt->ccs_mode); } +static bool gt_ccs_mode_default(struct xe_gt *gt) +{ + return gt->ccs_mode == 1; +} + static ssize_t num_cslices_show(struct device *kdev, struct device_attribute *attr, char *buf) @@ -117,12 +123,6 @@ 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 = kstrtou32(buff, 0, &num_engines); if (ret) return ret; @@ -139,21 +139,35 @@ ccs_mode_store(struct device *kdev, struct device_attribute *attr, } /* CCS mode can only be updated when there are no drm clients */ - mutex_lock(&xe->drm.filelist_mutex); + guard(mutex)(&xe->drm.filelist_mutex); 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; } - if (gt->ccs_mode != num_engines) { - xe_gt_info(gt, "Setting compute mode to %d\n", num_engines); - gt->ccs_mode = num_engines; - xe_gt_record_user_engines(gt); - xe_gt_reset(gt); + if (gt->ccs_mode == num_engines) + return count; + + /* + * Changing default CCS mode is only allowed when there + * are no VFs. Try to lockdown PF to find out. + */ + if (gt_ccs_mode_default(gt) && IS_SRIOV_PF(xe)) { + ret = xe_sriov_pf_lockdown(xe); + if (ret) { + xe_gt_dbg(gt, "Can't change CCS Mode: VFs are enabled\n"); + return ret; + } } - mutex_unlock(&xe->drm.filelist_mutex); + xe_gt_info(gt, "Setting compute mode to %d\n", num_engines); + gt->ccs_mode = num_engines; + xe_gt_record_user_engines(gt); + xe_gt_reset(gt); + + /* We may end PF lockdown once CCS mode is default again */ + if (gt_ccs_mode_default(gt) && IS_SRIOV_PF(xe)) + xe_sriov_pf_end_lockdown(xe); return count; }