target-arm: Use Neon for zero checking

Use Neon instructions to perform zero checking of
buffer. This is helps in reducing total migration time.

Use case: Idle VM live migration with 4 VCPUS and 8GB ram
running CentOS 7.

Without Neon, the Total migration time is 3.5 Sec

Migration status: completed
total time: 3560 milliseconds
downtime: 33 milliseconds
setup: 5 milliseconds
transferred ram: 297907 kbytes
throughput: 685.76 mbps
remaining ram: 0 kbytes
total ram: 8519872 kbytes
duplicate: 2062760 pages
skipped: 0 pages
normal: 69808 pages
normal bytes: 279232 kbytes
dirty sync count: 3

With Neon, the total migration time is 2.9 Sec

Migration status: completed
total time: 2960 milliseconds
downtime: 65 milliseconds
setup: 4 milliseconds
transferred ram: 299869 kbytes
throughput: 830.19 mbps
remaining ram: 0 kbytes
total ram: 8519872 kbytes
duplicate: 2064313 pages
skipped: 0 pages
normal: 70294 pages
normal bytes: 281176 kbytes
dirty sync count: 3
Signed-off-by: NVijaya Kumar K <vijayak@cavium.com>
Signed-off-by: NSuresh <ksuresh@cavium.com>
Acked-by: NPaolo Bonzini <pbonzini@redhat.com>
Message-id: 1467190029-694-2-git-send-email-vijayak@cavium.com
Reviewed-by: NPeter Maydell <peter.maydell@linaro.org>
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>

util/cutils.c

@@ -184,6 +184,13 @@ int qemu_fdatasync(int fd)
 #define SPLAT(p)       _mm_set1_epi8(*(p))
 #define ALL_EQ(v1, v2) (_mm_movemask_epi8(_mm_cmpeq_epi8(v1, v2)) == 0xFFFF)
 #define VEC_OR(v1, v2) (_mm_or_si128(v1, v2))
+#elif defined(__aarch64__)
+#include "arm_neon.h"
+#define VECTYPE        uint64x2_t
+#define ALL_EQ(v1, v2) \
+        ((vgetq_lane_u64(v1, 0) == vgetq_lane_u64(v2, 0)) && \
+         (vgetq_lane_u64(v1, 1) == vgetq_lane_u64(v2, 1)))
+#define VEC_OR(v1, v2) ((v1) | (v2))
 #else
 #define VECTYPE        unsigned long
 #define SPLAT(p)       (*(p) * (~0UL / 255))