target/arm: Introduce sve_vqm1_for_el_sm

When Streaming SVE mode is enabled, the size is taken from
SMCR_ELx instead of ZCR_ELx.  The format is shared, but the
set of vector lengths is not.  Further, Streaming SVE does
not require any particular length to be supported.

Adjust sve_vqm1_for_el to pass the current value of PSTATE.SM
to the new function.

Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20220620175235.60881-19-richard.henderson@linaro.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

2 files changed, 32 insertions, 9 deletions

diff --git a/target/arm/cpu.h b/target/arm/cpu.h
index c018f97..0295e85 100644
--- a/target/arm/cpu.h
+++ b/target/arm/cpu.h
@@ -1154,13 +1154,18 @@ int sve_exception_el(CPUARMState *env, int cur_el);
 int sme_exception_el(CPUARMState *env, int cur_el);
 
 /**
- * sve_vqm1_for_el:
+ * sve_vqm1_for_el_sm:
  * @env: CPUARMState
  * @el: exception level
+ * @sm: streaming mode
  *
- * Compute the current SVE vector length for @el, in units of
+ * Compute the current vector length for @el & @sm, in units of
  * Quadwords Minus 1 -- the same scale used for ZCR_ELx.LEN.
+ * If @sm, compute for SVL, otherwise NVL.
  */
+uint32_t sve_vqm1_for_el_sm(CPUARMState *env, int el, bool sm);
+
+/* Likewise, but using @sm = PSTATE.SM. */
 uint32_t sve_vqm1_for_el(CPUARMState *env, int el);
 
 static inline bool is_a64(CPUARMState *env)
diff --git a/target/arm/helper.c b/target/arm/helper.c
index a80ca46..2e4e739 100644
--- a/target/arm/helper.c
+++ b/target/arm/helper.c
@@ -6272,23 +6272,41 @@ int sme_exception_el(CPUARMState *env, int el)
 /*
  * Given that SVE is enabled, return the vector length for EL.
  */
-uint32_t sve_vqm1_for_el(CPUARMState *env, int el)
+uint32_t sve_vqm1_for_el_sm(CPUARMState *env, int el, bool sm)
 {
     ARMCPU *cpu = env_archcpu(env);
-    uint32_t len = cpu->sve_max_vq - 1;
+    uint64_t *cr = env->vfp.zcr_el;
+    uint32_t map = cpu->sve_vq.map;
+    uint32_t len = ARM_MAX_VQ - 1;
+
+    if (sm) {
+        cr = env->vfp.smcr_el;
+        map = cpu->sme_vq.map;
+    }
 
     if (el <= 1 && !el_is_in_host(env, el)) {
-        len = MIN(len, 0xf & (uint32_t)env->vfp.zcr_el[1]);
+        len = MIN(len, 0xf & (uint32_t)cr[1]);
     }
     if (el <= 2 && arm_feature(env, ARM_FEATURE_EL2)) {
-        len = MIN(len, 0xf & (uint32_t)env->vfp.zcr_el[2]);
+        len = MIN(len, 0xf & (uint32_t)cr[2]);
     }
     if (arm_feature(env, ARM_FEATURE_EL3)) {
-        len = MIN(len, 0xf & (uint32_t)env->vfp.zcr_el[3]);
+        len = MIN(len, 0xf & (uint32_t)cr[3]);
+    }
+
+    map &= MAKE_64BIT_MASK(0, len + 1);
+    if (map != 0) {
+        return 31 - clz32(map);
     }
 
-    len = 31 - clz32(cpu->sve_vq.map & MAKE_64BIT_MASK(0, len + 1));
-    return len;
+    /* Bit 0 is always set for Normal SVE -- not so for Streaming SVE. */
+    assert(sm);
+    return ctz32(cpu->sme_vq.map);
+}
+
+uint32_t sve_vqm1_for_el(CPUARMState *env, int el)
+{
+    return sve_vqm1_for_el_sm(env, el, FIELD_EX64(env->svcr, SVCR, SM));
 }
 
 static void zcr_write(CPUARMState *env, const ARMCPRegInfo *ri,