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

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Fabiano Rosas <farosas@suse.de>
Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Message-id: 20230112102436.1913-7-philmd@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>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
(cherry picked from commit f4318557149184d6dac99e561acabcb602a84ee1)
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>

diff --git a/linux-user/aarch64/cpu_loop.c b/linux-user/aarch64/cpu_loop.c
index 5e93d27d8f..2e2f7cf218 100644
--- a/linux-user/aarch64/cpu_loop.c
+++ b/linux-user/aarch64/cpu_loop.c
@@ -89,14 +89,8 @@ void cpu_loop(CPUARMState *env)
 
         switch (trapnr) {
         case EXCP_SWI:
-            /*
-             * On syscall, PSTATE.ZA is preserved, along with the ZA matrix.
-             * PSTATE.SM is cleared, per SMSTOP, which does ResetSVEState.
-             */
+            /* On syscall, PSTATE.ZA is preserved, PSTATE.SM is cleared. */
             aarch64_set_svcr(env, 0, R_SVCR_SM_MASK);
-            if (FIELD_EX64(env->svcr, SVCR, SM)) {
-                arm_rebuild_hflags(env);
-            }
             ret = do_syscall(env,
                              env->xregs[8],
                              env->xregs[0],
diff --git a/linux-user/aarch64/signal.c b/linux-user/aarch64/signal.c
index a326a6def5..b265cfd470 100644
--- a/linux-user/aarch64/signal.c
+++ b/linux-user/aarch64/signal.c
@@ -667,9 +667,6 @@ static void target_setup_frame(int usig, struct target_sigaction *ka,
 
     /* Invoke the signal handler with both SM and ZA disabled. */
     aarch64_set_svcr(env, 0, R_SVCR_SM_MASK | R_SVCR_ZA_MASK);
-    if (env->svcr) {
-        arm_rebuild_hflags(env);
-    }
 
     if (info) {
         tswap_siginfo(&frame->info, info);
diff --git a/target/arm/helper.c b/target/arm/helper.c
index 000632fe2b..4628b192f9 100644
--- a/target/arm/helper.c
+++ b/target/arm/helper.c
@@ -6442,6 +6442,9 @@ void aarch64_set_svcr(CPUARMState *env, uint64_t new, uint64_t mask)
 {
     uint64_t change = (env->svcr ^ new) & mask;
 
+    if (change == 0) {
+        return;
+    }
     env->svcr ^= change;
 
     if (change & R_SVCR_SM_MASK) {
@@ -6459,6 +6462,8 @@ void aarch64_set_svcr(CPUARMState *env, uint64_t new, uint64_t mask)
     if (change & new & R_SVCR_ZA_MASK) {
         memset(env->zarray, 0, sizeof(env->zarray));
     }
+
+    arm_rebuild_hflags(env);
 }
 
 static void svcr_write(CPUARMState *env, const ARMCPRegInfo *ri,
@@ -6467,7 +6472,6 @@ static void svcr_write(CPUARMState *env, const ARMCPRegInfo *ri,
     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);
 }
 
 static void smcr_write(CPUARMState *env, const ARMCPRegInfo *ri,
diff --git a/target/arm/sme_helper.c b/target/arm/sme_helper.c
index 247c2823ac..bbda651974 100644
--- a/target/arm/sme_helper.c
+++ b/target/arm/sme_helper.c
@@ -31,20 +31,12 @@
 
 void helper_set_pstate_sm(CPUARMState *env, uint32_t i)
 {
-    if (i == FIELD_EX64(env->svcr, SVCR, SM)) {
-        return;
-    }
     aarch64_set_svcr(env, 0, R_SVCR_SM_MASK);
-    arm_rebuild_hflags(env);
 }
 
 void helper_set_pstate_za(CPUARMState *env, uint32_t i)
 {
-    if (i == FIELD_EX64(env->svcr, SVCR, ZA)) {
-        return;
-    }
     aarch64_set_svcr(env, 0, R_SVCR_ZA_MASK);
-    arm_rebuild_hflags(env);
 }
 
 void helper_sme_zero(CPUARMState *env, uint32_t imm, uint32_t svl)
-- 
2.47.2