The patch below does not apply to the 5.4-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 58586680ffadc37636120d9f59955aa5f7a32b7d Mon Sep 17 00:00:00 2001

From: Chris Wilson chris@chris-wilson.co.uk Date: Mon, 25 Jan 2021 22:01:52 +0000 Subject: [PATCH] drm/i915: Disable atomics in L3 for gen9

Enabling atomic operations in L3 leads to unrecoverable GPU hangs, as the machine stops responding milliseconds after receipt of the reset request [GDRT]. By disabling the cached atomics, the hang do not occur and we presume the GPU would reset normally for similar hangs.

Sadly this is a shotgun approach, but since the impact is critical it is better to err on the safe side and work back from there.

Reported-by: Jason Ekstrand jason@jlekstrand.net Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=110998 Signed-off-by: Chris Wilson chris@chris-wilson.co.uk Cc: Jason Ekstrand jason@jlekstrand.net Cc: Mika Kuoppala mika.kuoppala@linux.intel.com Cc: Tvrtko Ursulin tvrtko.ursulin@linux.intel.com Cc: Joonas Lahtinen joonas.lahtinen@linux.intel.com Reviewed-by: Jason Ekstrand jason@jlesktrand.net Link: https://patchwork.freedesktop.org/patch/msgid/20210125220152.24070-1-chris@c... Cc: stable@vger.kernel.org (cherry picked from commit b267c7ae0ad5b437b068f46919b17f85000154b4) Signed-off-by: Rodrigo Vivi rodrigo.vivi@intel.com

diff --git a/drivers/gpu/drm/i915/gt/intel_workarounds.c b/drivers/gpu/drm/i915/gt/intel_workarounds.c index 3fdcd5ff71dd..ec366cf9ef56 100644 --- a/drivers/gpu/drm/i915/gt/intel_workarounds.c +++ b/drivers/gpu/drm/i915/gt/intel_workarounds.c @@ -1834,6 +1834,14 @@ rcs_engine_wa_init(struct intel_engine_cs *engine, struct i915_wa_list *wal) wa_write_or(wal, GEN8_L3SQCREG4, GEN8_LQSC_FLUSH_COHERENT_LINES); + + /* Disable atomics in L3 to prevent unrecoverable hangs */ + wa_write_clr_set(wal, GEN9_SCRATCH_LNCF1, + GEN9_LNCF_NONIA_COHERENT_ATOMICS_ENABLE, 0); + wa_write_clr_set(wal, GEN8_L3SQCREG4, + GEN8_LQSQ_NONIA_COHERENT_ATOMICS_ENABLE, 0); + wa_write_clr_set(wal, GEN9_SCRATCH1, + EVICTION_PERF_FIX_ENABLE, 0); }

if (IS_HASWELL(i915)) { diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h index 598abd2f5b5f..7146cd0f3256 100644 --- a/drivers/gpu/drm/i915/i915_reg.h +++ b/drivers/gpu/drm/i915/i915_reg.h @@ -8225,6 +8225,7 @@ enum { #define GEN11_LQSC_CLEAN_EVICT_DISABLE (1 << 6) #define GEN8_LQSC_RO_PERF_DIS (1 << 27) #define GEN8_LQSC_FLUSH_COHERENT_LINES (1 << 21) +#define GEN8_LQSQ_NONIA_COHERENT_ATOMICS_ENABLE REG_BIT(22)

/* GEN8 chicken */ #define HDC_CHICKEN0 _MMIO(0x7300) @@ -12107,6 +12108,12 @@ enum skl_power_gate { #define __GEN11_VCS2_MOCS0 0x10000 #define GEN11_MFX2_MOCS(i) _MMIO(__GEN11_VCS2_MOCS0 + (i) * 4)

+#define GEN9_SCRATCH_LNCF1 _MMIO(0xb008) +#define GEN9_LNCF_NONIA_COHERENT_ATOMICS_ENABLE REG_BIT(0) + +#define GEN9_SCRATCH1 _MMIO(0xb11c) +#define EVICTION_PERF_FIX_ENABLE REG_BIT(8) + #define GEN10_SCRATCH_LNCF2 _MMIO(0xb0a0) #define PMFLUSHDONE_LNICRSDROP (1 << 20) #define PMFLUSH_GAPL3UNBLOCK (1 << 21)