drm/i915/lrc: User PXP contexts requires runalone bit in lrc

On Meteorlake onwards, HW specs require that all user contexts that
run on render or compute engines and require PXP must enforce
run-alone bit in lrc. Add this enforcement for protected contexts.
Signed-off-by: Alan Previn <alan.previn.teres.alexis@intel.com>
Reviewed-by: Vivaik Balasubrawmanian <vivaik.balasubrawmanian@intel.com>
Signed-off-by: John Harrison <John.C.Harrison@Intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230917211933.1407559-4-alan.previn.teres.alexis@intel.com

drivers/gpu/drm/i915/gt/intel_engine_regs.h

@@ -177,6 +177,7 @@
 #define   CTX_CTRL_RS_CTX_ENABLE		REG_BIT(1)
 #define	  CTX_CTRL_ENGINE_CTX_SAVE_INHIBIT	REG_BIT(2)
 #define	  CTX_CTRL_INHIBIT_SYN_CTX_SWITCH	REG_BIT(3)
+#define	  GEN12_CTX_CTRL_RUNALONE_MODE		REG_BIT(7)
 #define	  GEN12_CTX_CTRL_OAR_CONTEXT_ENABLE	REG_BIT(8)
 #define RING_CTX_SR_CTL(base)			_MMIO((base) + 0x244)
 #define RING_SEMA_WAIT_POLL(base)		_MMIO((base) + 0x24c)

drivers/gpu/drm/i915/gt/intel_lrc.c

@@ -845,6 +845,27 @@ lrc_setup_indirect_ctx(u32 *regs,
 		lrc_ring_indirect_offset_default(engine) << 6;
 }
 
+static bool ctx_needs_runalone(const struct intel_context *ce)
+{
+	struct i915_gem_context *gem_ctx;
+	bool ctx_is_protected = false;
+
+	/*
+	 * On MTL and newer platforms, protected contexts require setting
+	 * the LRC run-alone bit or else the encryption will not happen.
+	 */
+	if (GRAPHICS_VER_FULL(ce->engine->i915) >= IP_VER(12, 70) &&
+	    (ce->engine->class == COMPUTE_CLASS || ce->engine->class == RENDER_CLASS)) {
+		rcu_read_lock();
+		gem_ctx = rcu_dereference(ce->gem_context);
+		if (gem_ctx)
+			ctx_is_protected = gem_ctx->uses_protected_content;
+		rcu_read_unlock();
+	}
+
+	return ctx_is_protected;
+}
+
 static void init_common_regs(u32 * const regs,
 			     const struct intel_context *ce,
 			     const struct intel_engine_cs *engine,
@@ -860,6 +881,8 @@ static void init_common_regs(u32 * const regs,
 	if (GRAPHICS_VER(engine->i915) < 11)
 		ctl |= _MASKED_BIT_DISABLE(CTX_CTRL_ENGINE_CTX_SAVE_INHIBIT |
 					   CTX_CTRL_RS_CTX_ENABLE);
+	if (ctx_needs_runalone(ce))
+		ctl |= _MASKED_BIT_ENABLE(GEN12_CTX_CTRL_RUNALONE_MODE);
 	regs[CTX_CONTEXT_CONTROL] = ctl;
 
 	regs[CTX_TIMESTAMP] = ce->stats.runtime.last;