On Thu, Sep 19 2024, Ganapatrao Kulkarni <gankulka...@os.amperecomputing.com>
wrote:
> I have modified as below diff to keep TCG if loop as it is and adding if
> for KVM case to clear/mask the MTE bits if MTE in KVM mode is not
> enabled by user command(if no mte=on).
>
> Is below diff makes sense?
>
> diff --git a/target/arm/cpu.c b/target/arm/cpu.c
> index a59417aac8..523996576d 100644
> --- a/target/arm/cpu.c
> +++ b/target/arm/cpu.c
> @@ -2390,15 +2390,20 @@ static void arm_cpu_realizefn(DeviceState *dev,
> Error **errp)
>
> #ifndef CONFIG_USER_ONLY
> /*
> - * If we do not have tag-memory provided by the TCG
> - * nor MTE at KVM enabled, reduce MTE support to
> - * instructions enabled at EL0.
> + * If we do not have tag-memory provided by the TCG,
> + * reduce MTE support to instructions enabled at EL0.
> * This matches Cortex-A710 BROADCASTMTE input being LOW.
> */
> - if (cpu->tag_memory == NULL && !cpu->kvm_mte) {
> + if (tcg_enabled() && cpu->tag_memory == NULL) {
> cpu->isar.id_aa64pfr1 =
> FIELD_DP64(cpu->isar.id_aa64pfr1, ID_AA64PFR1, MTE, 1);
> }
> +
> + /* Disable MTE, if it is not enabled by the user for KVM mode.
> + */
> + if (kvm_enabled() && !cpu->kvm_mte) {
> + FIELD_DP64(cpu->isar.id_aa64pfr1, ID_AA64PFR1, MTE, 0);
> + }
> #endif
> }
Wouldn't that be a possibly guest-visible change?
