[PATCH v3 06/10] target/arm: Disable FEAT_F64MM if maximum SVE vector size too small

[Richard Henderson <richard.henderson@linaro.org>]

All F64MM instructions operate on a 256-bit vector.
If only 128-bit vectors is supported by the cpu,
then the cpu cannot enable F64MM.

Suggested-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
---
 target/arm/cpu64.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/target/arm/cpu64.c b/target/arm/cpu64.c
index 200da1c489..c5c289eadf 100644
--- a/target/arm/cpu64.c
+++ b/target/arm/cpu64.c
@@ -237,6 +237,12 @@ void arm_cpu_sve_finalize(ARMCPU *cpu, Error **errp)
     /* From now on sve_max_vq is the actual maximum supported length. */
     cpu->sve_max_vq = max_vq;
     cpu->sve_vq.map = vq_map;
+
+    /* FEAT_F64MM requires the existence of a 256-bit vector size. */
+    if (max_vq < 2) {
+        cpu->isar.id_aa64zfr0 = FIELD_DP64(cpu->isar.id_aa64zfr0,
+                                           ID_AA64ZFR0, F64MM, 0);
+    }
 }
 
 /*
-- 
2.43.0