From cb11b3a6bd23f546e39283a4d41c0b6ac01b7528 Mon Sep 17 00:00:00 2001
From: Richard Henderson <richard.henderson@linaro.org>
Date: Fri, 17 Aug 2018 13:57:49 -0400
Subject: [PATCH] target/arm: Add sve-max-vq cpu property to -cpu max

This allows the default (and maximum) vector length to be set
from the command-line. Which is extraordinarily helpful in
debugging problems depending on vector length without having to
bake knowledge of PR_SET_SVE_VL into every guest binary.

Backports relevant parts of commit
adf92eab90e3f5f34c285da6d14d48952b7a8e72 from qemu
---
 qemu/target/arm/cpu.c   | 6 +++---
 qemu/target/arm/cpu.h   | 3 +++
 qemu/target/arm/cpu64.c | 2 ++
 3 files changed, 8 insertions(+), 3 deletions(-)

diff --git a/qemu/target/arm/cpu.c b/qemu/target/arm/cpu.c
index 8c2b93a2..101220b9 100644
--- a/qemu/target/arm/cpu.c
+++ b/qemu/target/arm/cpu.c
@@ -160,9 +160,9 @@ static void arm_cpu_reset(CPUState *s)
         env->cp15.cpacr_el1 = deposit64(env->cp15.cpacr_el1, 16, 2, 3);
         env->cp15.cptr_el[3] |= CPTR_EZ;
         /* with maximum vector length */
-        env->vfp.zcr_el[1] = ARM_MAX_VQ - 1;
-        env->vfp.zcr_el[2] = ARM_MAX_VQ - 1;
-        env->vfp.zcr_el[3] = ARM_MAX_VQ - 1;
+        env->vfp.zcr_el[1] = cpu->sve_max_vq - 1;
+        env->vfp.zcr_el[2] = env->vfp.zcr_el[1];
+        env->vfp.zcr_el[3] = env->vfp.zcr_el[1];
 #else
         /* Reset into the highest available EL */
         if (arm_feature(env, ARM_FEATURE_EL3)) {
diff --git a/qemu/target/arm/cpu.h b/qemu/target/arm/cpu.h
index bbbac208..bcaf999f 100644
--- a/qemu/target/arm/cpu.h
+++ b/qemu/target/arm/cpu.h
@@ -827,6 +827,9 @@ typedef struct ARMCPU {
     QLIST_HEAD(, ARMELChangeHook) el_change_hooks;
 
     int32_t node_id; /* NUMA node this CPU belongs to */
+
+    /* Used to set the maximum vector length the cpu will support.  */
+    uint32_t sve_max_vq;
 } ARMCPU;
 
 static inline ARMCPU *arm_env_get_cpu(CPUARMState *env)
diff --git a/qemu/target/arm/cpu64.c b/qemu/target/arm/cpu64.c
index 9d8a3c74..6595ffdb 100644
--- a/qemu/target/arm/cpu64.c
+++ b/qemu/target/arm/cpu64.c
@@ -225,6 +225,8 @@ static void aarch64_max_initfn(struct uc_struct *uc, Object *obj, void *opaque)
      */
     cpu->ctr = 0x80038003; /* 32 byte I and D cacheline size, VIPT icache */
     cpu->dcz_blocksize = 7; /*  512 bytes */
+
+    cpu->sve_max_vq = ARM_MAX_VQ;
 }
 
 typedef struct ARMCPUInfo {