target/arm: Use uint32_t instead of bitmap for sve vq's

The bitmap need only hold 15 bits; bitmap is over-complicated.
We can simplify operations quite a bit with plain logical ops.

The introduction of SVE_VQ_POW2_MAP eliminates the need for
looping in order to search for powers of two.  Simply perform
the logical ops and use count leading or trailing zeros as
required to find the result.

Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20220607203306.657998-12-richard.henderson@linaro.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

1 files changed, 3 insertions, 4 deletions

diff --git a/target/arm/kvm_arm.h b/target/arm/kvm_arm.h
index b7f78b5215..99017b635c 100644
--- a/target/arm/kvm_arm.h
+++ b/target/arm/kvm_arm.h
@@ -239,13 +239,12 @@ bool kvm_arm_get_host_cpu_features(ARMHostCPUFeatures *ahcf);
 /**
  * kvm_arm_sve_get_vls:
  * @cs: CPUState
- * @map: bitmap to fill in
  *
  * Get all the SVE vector lengths supported by the KVM host, setting
  * the bits corresponding to their length in quadwords minus one
- * (vq - 1) in @map up to ARM_MAX_VQ.
+ * (vq - 1) up to ARM_MAX_VQ.  Return the resulting map.
  */
-void kvm_arm_sve_get_vls(CPUState *cs, unsigned long *map);
+uint32_t kvm_arm_sve_get_vls(CPUState *cs);
 
 /**
  * kvm_arm_set_cpu_features_from_host:
@@ -439,7 +438,7 @@ static inline void kvm_arm_steal_time_finalize(ARMCPU *cpu, Error **errp)
     g_assert_not_reached();
 }
 
-static inline void kvm_arm_sve_get_vls(CPUState *cs, unsigned long *map)
+static inline uint32_t kvm_arm_sve_get_vls(CPUState *cs)
 {
     g_assert_not_reached();
 }