From 1d85a299c4db57c55e0229615132c964d17aa765 Mon Sep 17 00:00:00 2001 From: Uma Shankar Date: Tue, 7 Aug 2018 21:15:35 +0530 Subject: drm/i915: Lower RM timeout to avoid DSI hard hangs In BXT/APL, device 2 MMIO reads from MIPI controller requires its PLL to be turned ON. When MIPI PLL is turned off (MIPI Display is not active or connected), and someone (host or GT engine) tries to read MIPI registers, it causes hard hang. This is a hardware restriction or limitation. Driver by itself doesn't read MIPI registers when MIPI display is off. But any userspace application can submit unprivileged batch buffer for execution. In that batch buffer there can be mmio reads. And these reads are allowed even for unprivileged applications. If these register reads are for MIPI DSI controller and MIPI display is not active during that time, then the MMIO read operation causes system hard hang and only way to recover is hard reboot. A genuine process/application won't submit batch buffer like this and doesn't cause any issue. But on a compromised system, a malign userspace process/app can generate such batch buffer and can trigger system hard hang (denial of service attack). The fix is to lower the internal MMIO timeout value to an optimum value of 950us as recommended by hardware team. If the timeout is beyond 1ms (which will hit for any value we choose if MMIO READ on a DSI specific register is performed without PLL ON), it causes the system hang. But if the timeout value is lower than it will be below the threshold (even if timeout happens) and system will not get into a hung state. This will avoid a system hang without losing any programming or GT interrupts, taking the worst case of lowest CDCLK frequency and early DC5 abort into account. Signed-off-by: Uma Shankar Reviewed-by: Jon Bloomfield --- drivers/gpu/drm/i915/intel_pm.c | 8 ++++++++ 1 file changed, 8 insertions(+) (limited to 'drivers/gpu/drm/i915/intel_pm.c') diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c index 75ee027abb80..b5903ee25dea 100644 --- a/drivers/gpu/drm/i915/intel_pm.c +++ b/drivers/gpu/drm/i915/intel_pm.c @@ -126,6 +126,14 @@ static void bxt_init_clock_gating(struct drm_i915_private *dev_priv) */ I915_WRITE(GEN9_CLKGATE_DIS_0, I915_READ(GEN9_CLKGATE_DIS_0) | PWM1_GATING_DIS | PWM2_GATING_DIS); + + /* + * Lower the display internal timeout. + * This is needed to avoid any hard hangs when DSI port PLL + * is off and a MMIO access is attempted by any privilege + * application, using batch buffers or any other means. + */ + I915_WRITE(RM_TIMEOUT, MMIO_TIMEOUT_US(950)); } static void glk_init_clock_gating(struct drm_i915_private *dev_priv) -- cgit From 7e34f4e4aad3fd34c02b294a3cf2321adf5b4438 Mon Sep 17 00:00:00 2001 From: Imre Deak Date: Mon, 9 Jul 2018 18:24:27 +0300 Subject: drm/i915/gen8+: Add RC6 CTX corruption WA In some circumstances the RC6 context can get corrupted. We can detect this and take the required action, that is disable RC6 and runtime PM. The HW recovers from the corrupted state after a system suspend/resume cycle, so detect the recovery and re-enable RC6 and runtime PM. v2: rebase (Mika) v3: - Move intel_suspend_gt_powersave() to the end of the GEM suspend sequence. - Add commit message. v4: - Rebased on intel_uncore_forcewake_put(i915->uncore, ...) API change. v5: rebased on gem/gt split (Mika) Signed-off-by: Imre Deak Signed-off-by: Mika Kuoppala --- drivers/gpu/drm/i915/intel_pm.c | 114 +++++++++++++++++++++++++++++++++++++++- 1 file changed, 112 insertions(+), 2 deletions(-) (limited to 'drivers/gpu/drm/i915/intel_pm.c') diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c index b5903ee25dea..2efe1d12d5a9 100644 --- a/drivers/gpu/drm/i915/intel_pm.c +++ b/drivers/gpu/drm/i915/intel_pm.c @@ -8552,6 +8552,100 @@ static void intel_init_emon(struct drm_i915_private *dev_priv) dev_priv->ips.corr = (lcfuse & LCFUSE_HIV_MASK); } +static bool i915_rc6_ctx_corrupted(struct drm_i915_private *dev_priv) +{ + return !I915_READ(GEN8_RC6_CTX_INFO); +} + +static void i915_rc6_ctx_wa_init(struct drm_i915_private *i915) +{ + if (!NEEDS_RC6_CTX_CORRUPTION_WA(i915)) + return; + + if (i915_rc6_ctx_corrupted(i915)) { + DRM_INFO("RC6 context corrupted, disabling runtime power management\n"); + i915->gt_pm.rc6.ctx_corrupted = true; + i915->gt_pm.rc6.ctx_corrupted_wakeref = + intel_runtime_pm_get(&i915->runtime_pm); + } +} + +static void i915_rc6_ctx_wa_cleanup(struct drm_i915_private *i915) +{ + if (i915->gt_pm.rc6.ctx_corrupted) { + intel_runtime_pm_put(&i915->runtime_pm, + i915->gt_pm.rc6.ctx_corrupted_wakeref); + i915->gt_pm.rc6.ctx_corrupted = false; + } +} + +/** + * i915_rc6_ctx_wa_suspend - system suspend sequence for the RC6 CTX WA + * @i915: i915 device + * + * Perform any steps needed to clean up the RC6 CTX WA before system suspend. + */ +void i915_rc6_ctx_wa_suspend(struct drm_i915_private *i915) +{ + if (i915->gt_pm.rc6.ctx_corrupted) + intel_runtime_pm_put(&i915->runtime_pm, + i915->gt_pm.rc6.ctx_corrupted_wakeref); +} + +/** + * i915_rc6_ctx_wa_resume - system resume sequence for the RC6 CTX WA + * @i915: i915 device + * + * Perform any steps needed to re-init the RC6 CTX WA after system resume. + */ +void i915_rc6_ctx_wa_resume(struct drm_i915_private *i915) +{ + if (!i915->gt_pm.rc6.ctx_corrupted) + return; + + if (i915_rc6_ctx_corrupted(i915)) { + i915->gt_pm.rc6.ctx_corrupted_wakeref = + intel_runtime_pm_get(&i915->runtime_pm); + return; + } + + DRM_INFO("RC6 context restored, re-enabling runtime power management\n"); + i915->gt_pm.rc6.ctx_corrupted = false; +} + +static void intel_disable_rc6(struct drm_i915_private *dev_priv); + +/** + * i915_rc6_ctx_wa_check - check for a new RC6 CTX corruption + * @i915: i915 device + * + * Check if an RC6 CTX corruption has happened since the last check and if so + * disable RC6 and runtime power management. + * + * Return false if no context corruption has happened since the last call of + * this function, true otherwise. +*/ +bool i915_rc6_ctx_wa_check(struct drm_i915_private *i915) +{ + if (!NEEDS_RC6_CTX_CORRUPTION_WA(i915)) + return false; + + if (i915->gt_pm.rc6.ctx_corrupted) + return false; + + if (!i915_rc6_ctx_corrupted(i915)) + return false; + + DRM_NOTE("RC6 context corruption, disabling runtime power management\n"); + + intel_disable_rc6(i915); + i915->gt_pm.rc6.ctx_corrupted = true; + i915->gt_pm.rc6.ctx_corrupted_wakeref = + intel_runtime_pm_get_noresume(&i915->runtime_pm); + + return true; +} + void intel_init_gt_powersave(struct drm_i915_private *dev_priv) { struct intel_rps *rps = &dev_priv->gt_pm.rps; @@ -8565,6 +8659,8 @@ void intel_init_gt_powersave(struct drm_i915_private *dev_priv) pm_runtime_get(&dev_priv->drm.pdev->dev); } + i915_rc6_ctx_wa_init(dev_priv); + /* Initialize RPS limits (for userspace) */ if (IS_CHERRYVIEW(dev_priv)) cherryview_init_gt_powersave(dev_priv); @@ -8603,6 +8699,8 @@ void intel_cleanup_gt_powersave(struct drm_i915_private *dev_priv) if (IS_VALLEYVIEW(dev_priv)) valleyview_cleanup_gt_powersave(dev_priv); + i915_rc6_ctx_wa_cleanup(dev_priv); + if (!HAS_RC6(dev_priv)) pm_runtime_put(&dev_priv->drm.pdev->dev); } @@ -8631,7 +8729,7 @@ static inline void intel_disable_llc_pstate(struct drm_i915_private *i915) i915->gt_pm.llc_pstate.enabled = false; } -static void intel_disable_rc6(struct drm_i915_private *dev_priv) +static void __intel_disable_rc6(struct drm_i915_private *dev_priv) { lockdep_assert_held(&dev_priv->gt_pm.rps.lock); @@ -8650,6 +8748,15 @@ static void intel_disable_rc6(struct drm_i915_private *dev_priv) dev_priv->gt_pm.rc6.enabled = false; } +static void intel_disable_rc6(struct drm_i915_private *dev_priv) +{ + struct intel_rps *rps = &dev_priv->gt_pm.rps; + + mutex_lock(&rps->lock); + __intel_disable_rc6(dev_priv); + mutex_unlock(&rps->lock); +} + static void intel_disable_rps(struct drm_i915_private *dev_priv) { lockdep_assert_held(&dev_priv->gt_pm.rps.lock); @@ -8675,7 +8782,7 @@ void intel_disable_gt_powersave(struct drm_i915_private *dev_priv) { mutex_lock(&dev_priv->gt_pm.rps.lock); - intel_disable_rc6(dev_priv); + __intel_disable_rc6(dev_priv); intel_disable_rps(dev_priv); if (HAS_LLC(dev_priv)) intel_disable_llc_pstate(dev_priv); @@ -8702,6 +8809,9 @@ static void intel_enable_rc6(struct drm_i915_private *dev_priv) if (dev_priv->gt_pm.rc6.enabled) return; + if (dev_priv->gt_pm.rc6.ctx_corrupted) + return; + if (IS_CHERRYVIEW(dev_priv)) cherryview_enable_rc6(dev_priv); else if (IS_VALLEYVIEW(dev_priv)) -- cgit