Re: [PATCH v19 6/7] KVM: arm64: Add support for the KVM PTP service

[Zenghui Yu]

On 2021/3/30 22:54, Marc Zyngier wrote:
> +PTP_KVM support for arm/arm64
> +=============================
> +
> +PTP_KVM is used for high precision time sync between host and guests.
> +It relies on transferring the wall clock and counter value from the
> +host to the guest using a KVM-specific hypercall.
> +
> +* ARM_SMCCC_HYP_KVM_PTP_FUNC_ID: 0x86000001

Per include/linux/arm-smccc.h, this should be
ARM_SMCCC_VENDOR_HYP_KVM_PTP_FUNC_ID.

> +
> +This hypercall uses the SMC32/HVC32 calling convention:
> +
> +ARM_SMCCC_HYP_KVM_PTP_FUNC_ID

ditto

> +    =============    ==========    ==========
> +    Function ID:     (uint32)      0x86000001
> +    Arguments:       (uint32)      KVM_PTP_VIRT_COUNTER(0)
> +                                   KVM_PTP_PHYS_COUNTER(1)