linux-kernel - Re: [PATCH v5 4/6] psci: Add hvc call service for ptp

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Message-ID: <9641fbff-cfcd-4854-e0c9-0b97d44193ee@redhat.com>
Date:   Wed, 16 Oct 2019 09:24:54 +0200
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     Jianyong Wu <jianyong.wu@....com>, netdev@...r.kernel.org,
        yangbo.lu@....com, john.stultz@...aro.org, tglx@...utronix.de,
        sean.j.christopherson@...el.com, maz@...nel.org,
        richardcochran@...il.com, Mark.Rutland@....com, will@...nel.org,
        suzuki.poulose@....com
Cc:     linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        kvmarm@...ts.cs.columbia.edu, kvm@...r.kernel.org,
        Steve.Capper@....com, Kaly.Xin@....com, justin.he@....com,
        nd@....com
Subject: Re: [PATCH v5 4/6] psci: Add hvc call service for ptp_kvm.

On 15/10/19 12:48, Jianyong Wu wrote:
> diff --git a/drivers/clocksource/arm_arch_timer.c b/drivers/clocksource/arm_arch_timer.c
> index 07e57a49d1e8..3597f1f27b10 100644
> --- a/drivers/clocksource/arm_arch_timer.c
> +++ b/drivers/clocksource/arm_arch_timer.c
> @@ -1634,3 +1634,8 @@ static int __init arch_timer_acpi_init(struct acpi_table_header *table)
>  }
>  TIMER_ACPI_DECLARE(arch_timer, ACPI_SIG_GTDT, arch_timer_acpi_init);
>  #endif
> +
> +bool is_arm_arch_counter(void *cs)
> +{
> +	return (struct clocksource *)cs == &clocksource_counter;
> +}

As Thomas pointed out, any reason to have a void * here?

However, since he didn't like modifying the struct, here is an
alternative idea:

1) add a "struct clocksource*" argument to ktime_get_snapshot

2) return -ENODEV if the argument is not NULL and is not the current
clocksource

3) move the implementation of the hypercall to
drivers/clocksource/arm_arch_timer.c, so that it can call
ktime_get_snapshot(&systime_snapshot, &clocksource_counter);

Paolo