[PATCH v2 3/7] target/arm/sme: Introduce aarch64_set_svcr()

["Philippe Mathieu-Daudé" <philmd@linaro.org>]

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

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20230112004322.161330-1-richard.henderson@linaro.org>
[PMD: Split patch in multiple tiny steps]
Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
---
 linux-user/aarch64/cpu_loop.c | 2 +-
 linux-user/aarch64/signal.c   | 2 +-
 target/arm/cpu.h              | 1 +
 target/arm/helper.c           | 8 ++++++++
 target/arm/sme_helper.c       | 4 ++--
 5 files changed, 13 insertions(+), 4 deletions(-)

diff --git a/linux-user/aarch64/cpu_loop.c b/linux-user/aarch64/cpu_loop.c
index 9875d609a9..d53742e10b 100644
--- a/linux-user/aarch64/cpu_loop.c
+++ b/linux-user/aarch64/cpu_loop.c
@@ -93,8 +93,8 @@ void cpu_loop(CPUARMState *env)
              * On syscall, PSTATE.ZA is preserved, along with the ZA matrix.
              * PSTATE.SM is cleared, per SMSTOP, which does ResetSVEState.
              */
+            aarch64_set_svcr(env, 0, R_SVCR_SM_MASK);
             if (FIELD_EX64(env->svcr, SVCR, SM)) {
-                env->svcr = FIELD_DP64(env->svcr, SVCR, SM, 0);
                 arm_rebuild_hflags(env);
                 arm_reset_sve_state(env);
             }
diff --git a/linux-user/aarch64/signal.c b/linux-user/aarch64/signal.c
index 6a2c6e06d2..b6e4dcb494 100644
--- a/linux-user/aarch64/signal.c
+++ b/linux-user/aarch64/signal.c
@@ -669,11 +669,11 @@ static void target_setup_frame(int usig, struct target_sigaction *ka,
      * Invoke the signal handler with both SM and ZA disabled.
      * When clearing SM, ResetSVEState, per SMSTOP.
      */
+    aarch64_set_svcr(env, 0, R_SVCR_SM_MASK | R_SVCR_ZA_MASK);
     if (FIELD_EX64(env->svcr, SVCR, SM)) {
         arm_reset_sve_state(env);
     }
     if (env->svcr) {
-        env->svcr = 0;
         arm_rebuild_hflags(env);
     }
 
diff --git a/target/arm/cpu.h b/target/arm/cpu.h
index bf2bce046d..0484da3322 100644
--- a/target/arm/cpu.h
+++ b/target/arm/cpu.h
@@ -1123,6 +1123,7 @@ int aarch64_cpu_gdb_write_register(CPUState *cpu, uint8_t *buf, int reg);
 void aarch64_sve_narrow_vq(CPUARMState *env, unsigned vq);
 void aarch64_sve_change_el(CPUARMState *env, int old_el,
                            int new_el, bool el0_a64);
+void aarch64_set_svcr(CPUARMState *env, uint64_t new, uint64_t mask);
 void arm_reset_sve_state(CPUARMState *env);
 
 /*
diff --git a/target/arm/helper.c b/target/arm/helper.c
index cee3804354..b5626627a1 100644
--- a/target/arm/helper.c
+++ b/target/arm/helper.c
@@ -6722,11 +6722,19 @@ static CPAccessResult access_esm(CPUARMState *env, const ARMCPRegInfo *ri,
     return CP_ACCESS_OK;
 }
 
+void aarch64_set_svcr(CPUARMState *env, uint64_t new, uint64_t mask)
+{
+    uint64_t change = (env->svcr ^ new) & mask;
+
+    env->svcr ^= change;
+}
+
 static void svcr_write(CPUARMState *env, const ARMCPRegInfo *ri,
                        uint64_t value)
 {
     helper_set_pstate_sm(env, FIELD_EX64(value, SVCR, SM));
     helper_set_pstate_za(env, FIELD_EX64(value, SVCR, ZA));
+    aarch64_set_svcr(env, value, -1);
     arm_rebuild_hflags(env);
 }
 
diff --git a/target/arm/sme_helper.c b/target/arm/sme_helper.c
index b5aefa3eda..94dc084135 100644
--- a/target/arm/sme_helper.c
+++ b/target/arm/sme_helper.c
@@ -43,7 +43,7 @@ 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;
+    aarch64_set_svcr(env, 0, R_SVCR_SM_MASK);
     arm_reset_sve_state(env);
     arm_rebuild_hflags(env);
 }
@@ -53,7 +53,7 @@ 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;
+    aarch64_set_svcr(env, 0, R_SVCR_ZA_MASK);
 
     /*
      * ResetSMEState.
-- 
2.38.1