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

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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>
This commit is contained in:
Andrew Jones 2019-10-31 15:27:29 +01:00 • committed by Peter Maydell
parent 73234775ad
commit 0df9142d27
8 changed files with 606 additions and 9 deletions
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19
target/arm/cpu.c
View file

@ -1198,6 +1198,19 @@ static void arm_cpu_finalizefn(Object *obj)
#endif
}
void arm_cpu_finalize_features(ARMCPU *cpu, Error **errp)
{
Error *local_err = NULL;
if (arm_feature(&cpu->env, ARM_FEATURE_AARCH64)) {
arm_cpu_sve_finalize(cpu, &local_err);
if (local_err != NULL) {
error_propagate(errp, local_err);
return;
}
}
}
static void arm_cpu_realizefn(DeviceState *dev, Error **errp)
{
CPUState *cs = CPU(dev);
@ -1254,6 +1267,12 @@ static void arm_cpu_realizefn(DeviceState *dev, Error **errp)
return;
}
arm_cpu_finalize_features(cpu, &local_err);
if (local_err != NULL) {
error_propagate(errp, local_err);
return;
}
if (arm_feature(env, ARM_FEATURE_AARCH64) &&
cpu->has_vfp != cpu->has_neon) {
/*