target/arm: Implement SMSTART, SMSTOP

These two instructions are aliases of MSR (immediate).
Use the two helpers to properly implement svcr_write.

Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20220620175235.60881-11-richard.henderson@linaro.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

1 files changed, 61 insertions, 0 deletions

diff --git a/target/arm/sme_helper.c b/target/arm/sme_helper.c
new file mode 100644
index 0000000..b215725
--- /dev/null
+++ b/target/arm/sme_helper.c
@@ -0,0 +1,61 @@
+/*
+ * ARM SME Operations
+ *
+ * Copyright (c) 2022 Linaro, Ltd.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "qemu/osdep.h"
+#include "cpu.h"
+#include "internals.h"
+#include "exec/helper-proto.h"
+
+/* ResetSVEState */
+void arm_reset_sve_state(CPUARMState *env)
+{
+    memset(env->vfp.zregs, 0, sizeof(env->vfp.zregs));
+    /* Recall that FFR is stored as pregs[16]. */
+    memset(env->vfp.pregs, 0, sizeof(env->vfp.pregs));
+    vfp_set_fpcr(env, 0x0800009f);
+}
+
+void helper_set_pstate_sm(CPUARMState *env, uint32_t i)
+{
+    if (i == FIELD_EX64(env->svcr, SVCR, SM)) {
+        return;
+    }
+    env->svcr ^= R_SVCR_SM_MASK;
+    arm_reset_sve_state(env);
+}
+
+void helper_set_pstate_za(CPUARMState *env, uint32_t i)
+{
+    if (i == FIELD_EX64(env->svcr, SVCR, ZA)) {
+        return;
+    }
+    env->svcr ^= R_SVCR_ZA_MASK;
+
+    /*
+     * ResetSMEState.
+     *
+     * SetPSTATE_ZA zeros on enable and disable.  We can zero this only
+     * on enable: while disabled, the storage is inaccessible and the
+     * value does not matter.  We're not saving the storage in vmstate
+     * when disabled either.
+     */
+    if (i) {
+        memset(env->zarray, 0, sizeof(env->zarray));
+    }
+}