drm/i915: Perf_limit_reasons are only available for Gen11+

Register GT0_PERF_LIMIT_REASONS (0x1381a8) is available only for
Gen11+. Therefore ensure perf_limit_reasons sysfs/debugfs files are created
only for Gen11+. Otherwise on Gen < 5 accessing these files results in the
following oops:

<1> [88.829420] BUG: unable to handle page fault for address: ffffc90000bb81a8
<1> [88.829438] #PF: supervisor read access in kernel mode
<1> [88.829447] #PF: error_code(0x0000) - not-present page

Bspec: 20008
Bug: https://gitlab.freedesktop.org/drm/intel/-/issues/6863
Fixes: fe5979665f64 ("drm/i915/debugfs: Add perf_limit_reasons in debugfs")
Fixes: fa68bff7cf27 ("drm/i915/gt: Add sysfs throttle frequency interfaces")
Signed-off-by: Ashutosh Dixit <ashutosh.dixit@intel.com>
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220919162401.2077713-1-ashutosh.dixit@intel.com

diff --git a/drivers/gpu/drm/i915/gt/intel_gt.c b/drivers/gpu/drm/i915/gt/intel_gt.c
index abc46ba..5343a91 100644 (file)
--- a/drivers/gpu/drm/i915/gt/intel_gt.c
+++ b/drivers/gpu/drm/i915/gt/intel_gt.c
@@ -232,6 +232,10 @@ static void gen6_clear_engine_error_register(struct intel_engine_cs *engine)
 
 i915_reg_t intel_gt_perf_limit_reasons_reg(struct intel_gt *gt)
 {
+       /* GT0_PERF_LIMIT_REASONS is available only for Gen11+ */
+       if (GRAPHICS_VER(gt->i915) < 11)
+               return INVALID_MMIO_REG;
+
        return gt->type == GT_MEDIA ?
                MTL_MEDIA_PERF_LIMIT_REASONS : GT0_PERF_LIMIT_REASONS;
 }

diff --git a/drivers/gpu/drm/i915/gt/intel_gt_pm_debugfs.c b/drivers/gpu/drm/i915/gt/intel_gt_pm_debugfs.c
index 3157d06..9fd4d92 100644 (file)
--- a/drivers/gpu/drm/i915/gt/intel_gt_pm_debugfs.c
+++ b/drivers/gpu/drm/i915/gt/intel_gt_pm_debugfs.c
@@ -682,6 +682,14 @@ static int perf_limit_reasons_clear(void *data, u64 val)
 
        return 0;
 }
+
+static bool perf_limit_reasons_eval(void *data)
+{
+       struct intel_gt *gt = data;
+
+       return i915_mmio_reg_valid(intel_gt_perf_limit_reasons_reg(gt));
+}
+
 DEFINE_SIMPLE_ATTRIBUTE(perf_limit_reasons_fops, perf_limit_reasons_get,
                        perf_limit_reasons_clear, "%llu\n");
 
@@ -694,7 +702,7 @@ void intel_gt_pm_debugfs_register(struct intel_gt *gt, struct dentry *root)
                { "forcewake_user", &forcewake_user_fops, NULL},
                { "llc", &llc_fops, llc_eval },
                { "rps_boost", &rps_boost_fops, rps_eval },
-               { "perf_limit_reasons", &perf_limit_reasons_fops, NULL },
+               { "perf_limit_reasons", &perf_limit_reasons_fops, perf_limit_reasons_eval },
        };
 
        intel_gt_debugfs_register_files(root, files, ARRAY_SIZE(files), gt);

diff --git a/drivers/gpu/drm/i915/gt/intel_gt_sysfs_pm.c b/drivers/gpu/drm/i915/gt/intel_gt_sysfs_pm.c
index 54deae4..9041609 100644 (file)
--- a/drivers/gpu/drm/i915/gt/intel_gt_sysfs_pm.c
+++ b/drivers/gpu/drm/i915/gt/intel_gt_sysfs_pm.c
@@ -545,8 +545,7 @@ static INTEL_GT_RPS_BOOL_ATTR_RO(throttle_reason_ratl, RATL_MASK);
 static INTEL_GT_RPS_BOOL_ATTR_RO(throttle_reason_vr_thermalert, VR_THERMALERT_MASK);
 static INTEL_GT_RPS_BOOL_ATTR_RO(throttle_reason_vr_tdc, VR_TDC_MASK);
 
-static const struct attribute *freq_attrs[] = {
-       &dev_attr_punit_req_freq_mhz.attr,
+static const struct attribute *throttle_reason_attrs[] = {
        &attr_throttle_reason_status.attr,
        &attr_throttle_reason_pl1.attr,
        &attr_throttle_reason_pl2.attr,
@@ -791,12 +790,20 @@ void intel_gt_sysfs_pm_init(struct intel_gt *gt, struct kobject *kobj)
        if (!is_object_gt(kobj))
                return;
 
-       ret = sysfs_create_files(kobj, freq_attrs);
+       ret = sysfs_create_file(kobj, &dev_attr_punit_req_freq_mhz.attr);
        if (ret)
                drm_warn(&gt->i915->drm,
-                        "failed to create gt%u throttle sysfs files (%pe)",
+                        "failed to create gt%u punit_req_freq_mhz sysfs (%pe)",
                         gt->info.id, ERR_PTR(ret));
 
+       if (i915_mmio_reg_valid(intel_gt_perf_limit_reasons_reg(gt))) {
+               ret = sysfs_create_files(kobj, throttle_reason_attrs);
+               if (ret)
+                       drm_warn(&gt->i915->drm,
+                                "failed to create gt%u throttle sysfs files (%pe)",
+                                gt->info.id, ERR_PTR(ret));
+       }
+
        if (HAS_MEDIA_RATIO_MODE(gt->i915) && intel_uc_uses_guc_slpc(&gt->uc)) {
                ret = sysfs_create_files(kobj, media_perf_power_attrs);
                if (ret)