target/arm/cpu64: max cpu: Introduce sve<N> properties

Introduce cpu properties to give fine control over SVE vector lengths.
We introduce a property for each valid length up to the current
maximum supported, which is 2048-bits. The properties are named, e.g.
sve128, sve256, sve384, sve512, ..., where the number is the number of
bits. See the updates to docs/arm-cpu-features.rst for a description
of the semantics and for example uses.

Note, as sve-max-vq is still present and we'd like to be able to
support qmp_query_cpu_model_expansion with guests launched with e.g.
-cpu max,sve-max-vq=8 on their command lines, then we do allow
sve-max-vq and sve<N> properties to be provided at the same time, but
this is not recommended, and is why sve-max-vq is not mentioned in the
document.  If sve-max-vq is provided then it enables all lengths smaller
than and including the max and disables all lengths larger. It also has
the side-effect that no larger lengths may be enabled and that the max
itself cannot be disabled. Smaller non-power-of-two lengths may,
however, be disabled, e.g. -cpu max,sve-max-vq=4,sve384=off provides a
guest the vector lengths 128, 256, and 512 bits.

This patch has been co-authored with Richard Henderson, who reworked
the target/arm/cpu64.c changes in order to push all the validation and
auto-enabling/disabling steps into the finalizer, resulting in a nice
LOC reduction.

Signed-off-by: Andrew Jones <drjones@redhat.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Eric Auger <eric.auger@redhat.com>
Tested-by: Masayoshi Mizuma <m.mizuma@jp.fujitsu.com>
Reviewed-by: Beata Michalska <beata.michalska@linaro.org>
Message-id: 20191031142734.8590-5-drjones@redhat.com
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

include/qemu/bitops.h

@@ -20,6 +20,7 @@
 #define BITS_PER_LONG           (sizeof (unsigned long) * BITS_PER_BYTE)
 
 #define BIT(nr)                 (1UL << (nr))
+#define BIT_ULL(nr)             (1ULL << (nr))
 #define BIT_MASK(nr)            (1UL << ((nr) % BITS_PER_LONG))
 #define BIT_WORD(nr)            ((nr) / BITS_PER_LONG)
 #define BITS_TO_LONGS(nr)       DIV_ROUND_UP(nr, BITS_PER_BYTE * sizeof(long))