From 37b901003b7bb0c0b003550b1255b42b4fc68695 Mon Sep 17 00:00:00 2001 From: Francisco Jerez Date: Thu, 30 Jun 2016 17:49:18 -0700 Subject: [PATCH] i965: Fix remaining flush vs invalidate race conditions in brw_emit_pipe_control_flush. This hardware race condition has caused problems several times already (see "i965: Fix cache pollution race during L3 partitioning set-up.", "i965: Fix brw_render_cache_set_check_flush's PIPE_CONTROLs." and "i965: intel_texture_barrier reimplemented"). The problem is that whenever we attempt to both flush and invalidate multiple caches with a single pipe control command the flush and invalidation happen in reverse order, so the contents flushed from the R/W caches aren't guaranteed to become visible from the invalidated caches after the PIPE_CONTROL command completes execution if some concurrent rendering workload happened to pollute any of the invalidated R/O caches in the short window of time between the invalidation and flush. This makes sure that brw_emit_pipe_control_flush() has the effect expected by most callers of making the contents flushed from any R/W caches visible from the invalidated R/O caches. Cc: "12.0 11.1 11.2" Reviewed-by: Jason Ekstrand --- src/mesa/drivers/dri/i965/brw_pipe_control.c | 18 ++++++++++++++++++ src/mesa/drivers/dri/i965/intel_reg.h | 9 +++++++++ 2 files changed, 27 insertions(+) diff --git a/src/mesa/drivers/dri/i965/brw_pipe_control.c b/src/mesa/drivers/dri/i965/brw_pipe_control.c index 14a8f7c..05e8c05 100644 --- a/src/mesa/drivers/dri/i965/brw_pipe_control.c +++ b/src/mesa/drivers/dri/i965/brw_pipe_control.c @@ -96,6 +96,24 @@ gen7_cs_stall_every_four_pipe_controls(struct brw_context *brw, uint32_t flags) void brw_emit_pipe_control_flush(struct brw_context *brw, uint32_t flags) { + if (brw->gen >= 6 && + (flags & PIPE_CONTROL_CACHE_FLUSH_BITS) && + (flags & PIPE_CONTROL_CACHE_INVALIDATE_BITS)) { + /* A pipe control command with flush and invalidate bits set + * simultaneously is an inherently racy operation on Gen6+ if the + * contents of the flushed caches were intended to become visible from + * any of the invalidated caches. Split it in two PIPE_CONTROLs, the + * first one should stall the pipeline to make sure that the flushed R/W + * caches are coherent with memory once the specified R/O caches are + * invalidated. On pre-Gen6 hardware the (implicit) R/O cache + * invalidation seems to happen at the bottom of the pipeline together + * with any write cache flush, so this shouldn't be a concern. + */ + brw_emit_pipe_control_flush(brw, (flags & PIPE_CONTROL_CACHE_FLUSH_BITS) | + PIPE_CONTROL_CS_STALL); + flags &= ~(PIPE_CONTROL_CACHE_FLUSH_BITS | PIPE_CONTROL_CS_STALL); + } + if (brw->gen >= 8) { if (brw->gen == 8) gen8_add_cs_stall_workaround_bits(&flags); diff --git a/src/mesa/drivers/dri/i965/intel_reg.h b/src/mesa/drivers/dri/i965/intel_reg.h index 95365fe..7a82be4 100644 --- a/src/mesa/drivers/dri/i965/intel_reg.h +++ b/src/mesa/drivers/dri/i965/intel_reg.h @@ -134,6 +134,15 @@ #define PIPE_CONTROL_PPGTT_WRITE (0 << 2) #define PIPE_CONTROL_GLOBAL_GTT_WRITE (1 << 2) +#define PIPE_CONTROL_CACHE_FLUSH_BITS \ + (PIPE_CONTROL_DEPTH_CACHE_FLUSH | PIPE_CONTROL_DATA_CACHE_FLUSH | \ + PIPE_CONTROL_RENDER_TARGET_FLUSH) + +#define PIPE_CONTROL_CACHE_INVALIDATE_BITS \ + (PIPE_CONTROL_STATE_CACHE_INVALIDATE | PIPE_CONTROL_CONST_CACHE_INVALIDATE | \ + PIPE_CONTROL_VF_CACHE_INVALIDATE | PIPE_CONTROL_TEXTURE_CACHE_INVALIDATE | \ + PIPE_CONTROL_INSTRUCTION_INVALIDATE) + /** @} */ #define XY_SETUP_BLT_CMD (CMD_2D | (0x01 << 22)) -- 2.7.4