Merge tag 'drm-intel-gt-next-2023-04-06' of git://anongit.freedesktop.org/drm/drm-intel into drm-next

UAPI Changes:

- (Build-time only, should not have any impact)
  drm/i915/uapi: Replace fake flex-array with flexible-array member

  "Zero-length arrays as fake flexible arrays are deprecated and we are
  moving towards adopting C99 flexible-array members instead."

  This is on core kernel request moving towards GCC 13.

Driver Changes:

- Fix context runtime accounting on sysfs fdinfo for heavy workloads (Tvrtko)
- Add support for OA media units on MTL (Umesh)
- Add new workarounds for Meteorlake (Daniele, Radhakrishna, Haridhar)
- Fix sysfs to read actual frequency for MTL and Gen6 and earlier
  (Ashutosh)
- Synchronize i915/BIOS on C6 enabling on MTL (Vinay)
- Fix DMAR error noise due to GPU error capture (Andrej)
- Fix forcewake during BAR resize on discrete (Andrzej)
- Flush lmem contents after construction on discrete (Chris)
- Fix GuC loading timeout on systems where IFWI programs low boot
  frequency (John)
- Fix race condition UAF in i915_perf_add_config_ioctl (Min)

- Sanitycheck MMIO access early in driver load and during forcewake
  (Matt)
- Wakeref fixes for GuC RC error scenario and active VM tracking (Chris)
- Cancel HuC delayed load timer on reset (Daniele)
- Limit double GT reset to pre-MTL (Daniele)
- Use i915 instead of dev_priv insied the file_priv structure (Andi)
- Improve GuC load error reporting (John)
- Simplify VCS/BSD engine selection logic (Tvrtko)
- Perform uc late init after probe error injection (Andrzej)
- Fix format for perf_limit_reasons in debugfs (Vinay)
- Create per-gt debugfs files (Andi)

- Documentation and kerneldoc fixes (Nirmoy, Lee)
- Selftest improvements (Fei, Jonathan)

Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
From: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/ZC6APj/feB+jBf2d@jlahtine-mobl.ger.corp.intel.com

1 files changed, 44 insertions, 3 deletions

diff --git a/drivers/gpu/drm/i915/intel_uncore.c b/drivers/gpu/drm/i915/intel_uncore.c
index e1e1f34490c8..796ebfe6c550 100644
--- a/drivers/gpu/drm/i915/intel_uncore.c
+++ b/drivers/gpu/drm/i915/intel_uncore.c
@@ -177,12 +177,19 @@ wait_ack_set(const struct intel_uncore_forcewake_domain *d,
 static inline void
 fw_domain_wait_ack_clear(const struct intel_uncore_forcewake_domain *d)
 {
-	if (wait_ack_clear(d, FORCEWAKE_KERNEL)) {
+	if (!wait_ack_clear(d, FORCEWAKE_KERNEL))
+		return;
+
+	if (fw_ack(d) == ~0)
+		drm_err(&d->uncore->i915->drm,
+			"%s: MMIO unreliable (forcewake register returns 0xFFFFFFFF)!\n",
+			intel_uncore_forcewake_domain_to_str(d->id));
+	else
 		drm_err(&d->uncore->i915->drm,
 			"%s: timed out waiting for forcewake ack to clear.\n",
 			intel_uncore_forcewake_domain_to_str(d->id));
-		add_taint_for_CI(d->uncore->i915, TAINT_WARN); /* CI now unreliable */
-	}
+
+	add_taint_for_CI(d->uncore->i915, TAINT_WARN); /* CI now unreliable */
 }
 
 enum ack_type {
@@ -2602,11 +2609,45 @@ static int uncore_forcewake_init(struct intel_uncore *uncore)
 	return 0;
 }
 
+static int sanity_check_mmio_access(struct intel_uncore *uncore)
+{
+	struct drm_i915_private *i915 = uncore->i915;
+
+	if (GRAPHICS_VER(i915) < 8)
+		return 0;
+
+	/*
+	 * Sanitycheck that MMIO access to the device is working properly.  If
+	 * the CPU is unable to communcate with a PCI device, BAR reads will
+	 * return 0xFFFFFFFF.  Let's make sure the device isn't in this state
+	 * before we start trying to access registers.
+	 *
+	 * We use the primary GT's forcewake register as our guinea pig since
+	 * it's been around since HSW and it's a masked register so the upper
+	 * 16 bits can never read back as 1's if device access is operating
+	 * properly.
+	 *
+	 * If MMIO isn't working, we'll wait up to 2 seconds to see if it
+	 * recovers, then give up.
+	 */
+#define COND (__raw_uncore_read32(uncore, FORCEWAKE_MT) != ~0)
+	if (wait_for(COND, 2000) == -ETIMEDOUT) {
+		drm_err(&i915->drm, "Device is non-operational; MMIO access returns 0xFFFFFFFF!\n");
+		return -EIO;
+	}
+
+	return 0;
+}
+
 int intel_uncore_init_mmio(struct intel_uncore *uncore)
 {
 	struct drm_i915_private *i915 = uncore->i915;
 	int ret;
 
+	ret = sanity_check_mmio_access(uncore);
+	if (ret)
+		return ret;
+
 	/*
 	 * The boot firmware initializes local memory and assesses its health.
 	 * If memory training fails, the punit will have been instructed to