From: Chris Wilson chris@chris-wilson.co.uk

Don't allow two engines to be reset in parallel, as they would both try to select a reset bit (and send requests to common registers) and wait on that register, at the same time. Serialize control of the reset requests/acks using the uncore->lock, which will also ensure that no other GT state changes at the same time as the actual reset.

Cc: stable@vger.kernel.org # v4.4 and upper Reported-by: Mika Kuoppala mika.kuoppala@linux.intel.com Signed-off-by: Chris Wilson chris@chris-wilson.co.uk Acked-by: Mika Kuoppala mika.kuoppala@linux.intel.com Reviewed-by: Andi Shyti andi.shyti@intel.com Reviewed-by: Andrzej Hajda andrzej.hajda@intel.com Acked-by: Thomas Hellström thomas.hellstrom@linux.intel.com Signed-off-by: Mauro Carvalho Chehab mchehab@kernel.org ---

See [PATCH v4 0/2] at: https://lore.kernel.org/all/cover.1657522157.git.mchehab@kernel.org/

drivers/gpu/drm/i915/gt/intel_reset.c | 37 ++++++++++++++++++++------- 1 file changed, 28 insertions(+), 9 deletions(-)

diff --git a/drivers/gpu/drm/i915/gt/intel_reset.c b/drivers/gpu/drm/i915/gt/intel_reset.c index a5338c3fde7a..c68d36fb5bbd 100644 --- a/drivers/gpu/drm/i915/gt/intel_reset.c +++ b/drivers/gpu/drm/i915/gt/intel_reset.c @@ -300,9 +300,9 @@ static int gen6_hw_domain_reset(struct intel_gt *gt, u32 hw_domain_mask) return err; }

-static int gen6_reset_engines(struct intel_gt *gt, - intel_engine_mask_t engine_mask, - unsigned int retry) +static int __gen6_reset_engines(struct intel_gt *gt, + intel_engine_mask_t engine_mask, + unsigned int retry) { struct intel_engine_cs *engine; u32 hw_mask; @@ -321,6 +321,20 @@ static int gen6_reset_engines(struct intel_gt *gt, return gen6_hw_domain_reset(gt, hw_mask); }

+static int gen6_reset_engines(struct intel_gt *gt, + intel_engine_mask_t engine_mask, + unsigned int retry) +{ + unsigned long flags; + int ret; + + spin_lock_irqsave(&gt->uncore->lock, flags); + ret = __gen6_reset_engines(gt, engine_mask, retry); + spin_unlock_irqrestore(&gt->uncore->lock, flags); + + return ret; +} + static struct intel_engine_cs *find_sfc_paired_vecs_engine(struct intel_engine_cs *engine) { int vecs_id; @@ -487,9 +501,9 @@ static void gen11_unlock_sfc(struct intel_engine_cs *engine) rmw_clear_fw(uncore, sfc_lock.lock_reg, sfc_lock.lock_bit); }

-static int gen11_reset_engines(struct intel_gt *gt, - intel_engine_mask_t engine_mask, - unsigned int retry) +static int __gen11_reset_engines(struct intel_gt *gt, + intel_engine_mask_t engine_mask, + unsigned int retry) { struct intel_engine_cs *engine; intel_engine_mask_t tmp; @@ -583,8 +597,11 @@ static int gen8_reset_engines(struct intel_gt *gt, struct intel_engine_cs *engine; const bool reset_non_ready = retry >= 1; intel_engine_mask_t tmp; + unsigned long flags; int ret;

+ spin_lock_irqsave(&gt->uncore->lock, flags); + for_each_engine_masked(engine, gt, engine_mask, tmp) { ret = gen8_engine_reset_prepare(engine); if (ret && !reset_non_ready) @@ -612,17 +629,19 @@ static int gen8_reset_engines(struct intel_gt *gt, * This is best effort, so ignore any error from the initial reset. */ if (IS_DG2(gt->i915) && engine_mask == ALL_ENGINES) - gen11_reset_engines(gt, gt->info.engine_mask, 0); + __gen11_reset_engines(gt, gt->info.engine_mask, 0);

if (GRAPHICS_VER(gt->i915) >= 11) - ret = gen11_reset_engines(gt, engine_mask, retry); + ret = __gen11_reset_engines(gt, engine_mask, retry); else - ret = gen6_reset_engines(gt, engine_mask, retry); + ret = __gen6_reset_engines(gt, engine_mask, retry);

skip_reset: for_each_engine_masked(engine, gt, engine_mask, tmp) gen8_engine_reset_cancel(engine);

+ spin_unlock_irqrestore(&gt->uncore->lock, flags); + return ret; }