[PULL 03/15] target/arm: Fix aarch64_sve_change_el for SME

[Peter Maydell]

From: Richard Henderson <richard.henderson@linaro.org>

We were only checking for SVE disabled and not taking into
account PSTATE.SM to check SME disabled, which resulted in
vectors being incorrectly truncated.

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20220713045848.217364-3-richard.henderson@linaro.org
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
---
 target/arm/helper.c | 31 +++++++++++++++++++++++++------
 1 file changed, 25 insertions(+), 6 deletions(-)

diff --git a/target/arm/helper.c b/target/arm/helper.c
index 6fff7fc64fd..24c45a9bf31 100644
--- a/target/arm/helper.c
+++ b/target/arm/helper.c
@@ -11228,6 +11228,21 @@ void aarch64_sve_narrow_vq(CPUARMState *env, unsigned 
vq)
     }
 }
 
+static uint32_t sve_vqm1_for_el_sm_ena(CPUARMState *env, int el, bool sm)
+{
+    int exc_el;
+
+    if (sm) {
+        exc_el = sme_exception_el(env, el);
+    } else {
+        exc_el = sve_exception_el(env, el);
+    }
+    if (exc_el) {
+        return 0; /* disabled */
+    }
+    return sve_vqm1_for_el_sm(env, el, sm);
+}
+
 /*
  * Notice a change in SVE vector size when changing EL.
  */
@@ -11236,7 +11251,7 @@ void aarch64_sve_change_el(CPUARMState *env, int old_el,
 {
     ARMCPU *cpu = env_archcpu(env);
     int old_len, new_len;
-    bool old_a64, new_a64;
+    bool old_a64, new_a64, sm;
 
     /* Nothing to do if no SVE.  */
     if (!cpu_isar_feature(aa64_sve, cpu)) {
@@ -11256,7 +11271,8 @@ void aarch64_sve_change_el(CPUARMState *env, int old_el,
      * invoke ResetSVEState when taking an exception from, or
      * returning to, AArch32 state when PSTATE.SM is enabled.
      */
-    if (old_a64 != new_a64 && FIELD_EX64(env->svcr, SVCR, SM)) {
+    sm = FIELD_EX64(env->svcr, SVCR, SM);
+    if (old_a64 != new_a64 && sm) {
         arm_reset_sve_state(env);
         return;
     }
@@ -11273,10 +11289,13 @@ void aarch64_sve_change_el(CPUARMState *env, int 
old_el,
      * we already have the correct register contents when encountering the
      * vq0->vq0 transition between EL0->EL1.
      */
-    old_len = (old_a64 && !sve_exception_el(env, old_el)
-               ? sve_vqm1_for_el(env, old_el) : 0);
-    new_len = (new_a64 && !sve_exception_el(env, new_el)
-               ? sve_vqm1_for_el(env, new_el) : 0);
+    old_len = new_len = 0;
+    if (old_a64) {
+        old_len = sve_vqm1_for_el_sm_ena(env, old_el, sm);
+    }
+    if (new_a64) {
+        new_len = sve_vqm1_for_el_sm_ena(env, new_el, sm);
+    }
 
     /* When changing vector length, clear inaccessible state.  */
     if (new_len < old_len) {
-- 
2.25.1