Re: [RFC PATCH 10/11] kvm/arm: implement a basic hypercall handler

["Philippe Mathieu-Daudé" <philmd@linaro.org>]

On 17/6/25 18:33, Alex Bennée wrote:
> For now just deal with the basic version probe we see during startup.
> 
> Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
> ---
>   target/arm/kvm.c        | 44 +++++++++++++++++++++++++++++++++++++++++
>   target/arm/trace-events |  1 +
>   2 files changed, 45 insertions(+)


> +/*
> + * The guest is making a hypercall or firmware call. We can handle a
> + * limited number of them (e.g. PSCI) but we can't emulate a true
> + * firmware. This is an abbreviated version of
> + * kvm_smccc_call_handler() in the kernel and the TCG only arm_handle_psci_call().
> + *
> + * In the SplitAccel case we would be transitioning to execute EL2+
> + * under TCG.
> + */
> +static int kvm_arm_handle_hypercall(ARMCPU *cpu,
> +                                    int esr_ec)
> +{
> +    CPUARMState *env = &cpu->env;
> +    int32_t ret = 0;
> +
> +    trace_kvm_hypercall(esr_ec, env->xregs[0]);
> +

Should we make arm_is_psci_call() generic to be able to use it here?

> +    switch (env->xregs[0]) {
> +    case QEMU_PSCI_0_2_FN_PSCI_VERSION:
> +        ret = QEMU_PSCI_VERSION_1_1;
> +        break;
> +    case QEMU_PSCI_0_2_FN_MIGRATE_INFO_TYPE:
> +        ret = QEMU_PSCI_0_2_RET_TOS_MIGRATION_NOT_REQUIRED; /* No trusted OS */
> +        break;
> +    case QEMU_PSCI_1_0_FN_PSCI_FEATURES:
> +        ret = QEMU_PSCI_RET_NOT_SUPPORTED;
> +        break;
> +    default:
> +        qemu_log_mask(LOG_UNIMP, "%s: unhandled hypercall %"PRIx64"\n",
> +                      __func__, env->xregs[0]);
> +        return -1;
> +    }
> +
> +    env->xregs[0] = ret;
> +    return 0;
> +}