drm/i915/gen9: Clear residual context state on context switch

commit bc8a76a152c5f9ef3b48104154a65a68a8b76946 upstream.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/gpu/drm/i915/intel_lrc.c b/drivers/gpu/drm/i915/intel_lrc.c
index 6937ef0b4bfc9d2a700262c0d01952efafd8b375..13e97faabaa74d808ede2f59b69a8bd4247111c9 100644 (file)
--- a/drivers/gpu/drm/i915/intel_lrc.c
+++ b/drivers/gpu/drm/i915/intel_lrc.c
@@ -1562,6 +1562,15 @@ 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_GLOBAL_GTT_IVB |
+                                      PIPE_CONTROL_CS_STALL |
+                                      PIPE_CONTROL_QW_WRITE,
+                                      i915_ggtt_offset(engine->scratch) +
+                                      2 * CACHELINE_BYTES);
+
        batch = emit_lri(batch, lri, ARRAY_SIZE(lri));
 
        /* WaClearSlmSpaceAtContextSwitch:kbl */