From bc8a76a152c5f9ef3b48104154a65a68a8b76946 Mon Sep 17 00:00:00 2001
From: Akeem G Abodunrin <akeem.g.abodunrin@intel.com>
Date: Wed, 8 Jan 2020 09:25:00 -0800
Subject: drm/i915/gen9: Clear residual context state on context switch
Git-commit: bc8a76a152c5f9ef3b48104154a65a68a8b76946
Patch-mainline: v5.5-rc7
References: bsc#1152489
Intel ID: PSIRT-TA-201910-001
CVEID: CVE-2019-14615
Intel GPU Hardware prior to Gen11 does not clear EU state
during a context switch. This can result in information
leakage between contexts.
For Gen8 and Gen9, hardware provides a mechanism for
fast cleardown of the EU state, by issuing a PIPE_CONTROL
with bit 27 set. We can use this in a context batch buffer
to explicitly cleardown the state on every context switch.
As this workaround is already in place for gen8, we can borrow
the code verbatim for Gen9.
Signed-off-by: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Signed-off-by: Akeem G Abodunrin <akeem.g.abodunrin@intel.com>
Cc: Kumar Valsan Prathap <prathap.kumar.valsan@intel.com>
Cc: Chris Wilson <chris.p.wilson@intel.com>
Cc: Balestrieri Francesco <francesco.balestrieri@intel.com>
Cc: Bloomfield Jon <jon.bloomfield@intel.com>
Cc: Dutt Sudeep <sudeep.dutt@intel.com>
Acked-by: Thomas Zimmermann <tzimmermann@suse.de>
---
drivers/gpu/drm/i915/gt/intel_lrc.c | 8 ++++++++
1 file changed, 8 insertions(+)
diff --git a/drivers/gpu/drm/i915/gt/intel_lrc.c b/drivers/gpu/drm/i915/gt/intel_lrc.c
index 75dd0e0367b7..f0485784afbe 100644
--- a/drivers/gpu/drm/i915/gt/intel_lrc.c
+++ b/drivers/gpu/drm/i915/gt/intel_lrc.c
@@ -2664,6 +2664,14 @@ static u32 *gen9_init_indirectctx_bb(struct intel_engine_cs *engine, u32 *batch)
/* WaFlushCoherentL3CacheLinesAtContextSwitch:skl,bxt,glk */
batch = gen8_emit_flush_coherentl3_wa(engine, batch);
+ /* WaClearSlmSpaceAtContextSwitch:skl,bxt,kbl,glk,cfl */
+ batch = gen8_emit_pipe_control(batch,
+ PIPE_CONTROL_FLUSH_L3 |
+ PIPE_CONTROL_STORE_DATA_INDEX |
+ PIPE_CONTROL_CS_STALL |
+ PIPE_CONTROL_QW_WRITE,
+ LRC_PPHWSP_SCRATCH_ADDR);
+
batch = emit_lri(batch, lri, ARRAY_SIZE(lri));
/* WaMediaPoolStateCmdInWABB:bxt,glk */
--
2.28.0