Hi Paolo, > -----Original Message----- > From: Paolo Bonzini <[email protected]> > Sent: Wednesday, October 9, 2019 2:36 PM > To: Jianyong Wu (Arm Technology China) <[email protected]>; Marc > Zyngier <[email protected]>; [email protected]; [email protected]; > [email protected]; [email protected]; [email protected]; > [email protected]; Mark Rutland <[email protected]>; Will > Deacon <[email protected]>; Suzuki Poulose > <[email protected]> > Cc: [email protected]; [email protected]; Steve Capper > <[email protected]>; Kaly Xin (Arm Technology China) > <[email protected]>; Justin He (Arm Technology China) > <[email protected]>; nd <[email protected]>; linux-arm- > [email protected] > Subject: Re: [RFC PATCH v3 4/6] psci: Add hvc call service for ptp_kvm. > > On 09/10/19 07:21, Jianyong Wu (Arm Technology China) wrote: > > As ptp_kvm clock has fixed to arm arch system counter in patch set v4, > > we need check if the current clocksource is system counter when return > > clock cycle in host, so a helper needed to return the current > > clocksource. Could I add this helper in next patch set? > > You don't need a helper. You need to return the ARM arch counter > clocksource in the struct system_counterval_t that you return. > get_device_system_crosststamp will then check that the clocksource > matches the active one. > We must ensure both of the host and guest using the same clocksource. get_device_system_crosststamp will check the clocksource of guest and we also need check the clocksource in host, and struct type can't be transferred from host to guest using arm hypercall. now we lack of a mechanism to check the current clocksource. I think this will be useful if we add one.
Thanks Jianyong Wu > Paolo
