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From: Thomas Gleixner <tglx@linutronix.de>
To: Hikaru Nishida <hikalium@chromium.org>,
	linux-kernel@vger.kernel.org, dme@dme.org, mlevitsk@redhat.com
Cc: suleiman@google.com, Hikaru Nishida <hikalium@chromium.org>,
	Borislav Petkov <bp@alien8.de>, "H. Peter Anvin" <hpa@zytor.com>,
	Ingo Molnar <mingo@redhat.com>, Jim Mattson <jmattson@google.com>,
	Joerg Roedel <joro@8bytes.org>,
	John Stultz <john.stultz@linaro.org>,
	Paolo Bonzini <pbonzini@redhat.com>,
	Sean Christopherson <seanjc@google.com>,
	Stephen Boyd <sboyd@kernel.org>,
	Vitaly Kuznetsov <vkuznets@redhat.com>,
	Wanpeng Li <wanpengli@tencent.com>,
	kvm@vger.kernel.org, x86@kernel.org
Subject: Re: [v2 PATCH 3/4] x86/kvm: Add host side support for virtual suspend time injection
Date: Tue, 10 Aug 2021 17:21:05 +0200	[thread overview]
Message-ID: <87r1f1qqam.ffs@tglx> (raw)
In-Reply-To: <20210806190607.v2.3.Ib0cb8ecae99f0ccd0e2814b310adba00b9e81d94@changeid>

On Fri, Aug 06 2021 at 19:07, Hikaru Nishida wrote:

> This patch implements virtual suspend time injection support for kvm

git grep 'This patch' Documentation/process/

> hosts.
>
> If this functionality is enabled and the guest requests it, the host
> will stop all the clocks observed by the guest during the host's
> suspension and report the duration of suspend to the guest through
> struct kvm_host_suspend_time to give a chance to adjust CLOCK_BOOTTIME
> to the guest. This mechanism can be used to align the guest's clock
> behavior to the hosts' ones.
>
> Signed-off-by: Hikaru Nishida <hikalium@chromium.org>
> ---
>
>  arch/x86/include/asm/kvm_host.h |   5 ++
>  arch/x86/kvm/Kconfig            |  13 ++++
>  arch/x86/kvm/cpuid.c            |   4 ++
>  arch/x86/kvm/x86.c              | 109 +++++++++++++++++++++++++++++++-
>  include/linux/kvm_host.h        |   8 +++
>  kernel/time/timekeeping.c       |   3 +

Please split this into adding the infrastructure and then implementing
the x86 side of it.

>  
> +#ifdef CONFIG_KVM_VIRT_SUSPEND_TIMING
> +void kvm_arch_timekeeping_inject_sleeptime(const struct timespec64 *delta);
 +#else
 +static inline void kvm_arch_timekeeping_inject_sleeptime(const struct timespec64 *delta){}
> +#endif /* CONFIG_KVM_VIRT_SUSPEND_TIMING */
> +
>  #endif
> diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c
> index 233ceb6cce1f..3ac3fb479981 100644
> --- a/kernel/time/timekeeping.c
> +++ b/kernel/time/timekeeping.c
> @@ -1797,6 +1797,9 @@ void timekeeping_resume(void)
>  	if (inject_sleeptime) {
>  		suspend_timing_needed = false;
>  		__timekeeping_inject_sleeptime(tk, &ts_delta);
> +#ifdef CONFIG_KVM_VIRT_SUSPEND_TIMING
> +		kvm_arch_timekeeping_inject_sleeptime(&ts_delta);
> +#endif

which get's rid of these ugly ifdefs.

Also this is the wrong place because sleep time can be injected from
other places as well. This should be in __timekeeping_inject_sleeptime()
if at all.

Thanks,

        tglx

  reply	other threads:[~2021-08-10 15:21 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-08-06 10:07 [v2 PATCH 0/4] x86/kvm: Virtual suspend time injection support Hikaru Nishida
2021-08-06 10:07 ` [v2 PATCH 1/4] x86/kvm: Reserve KVM_FEATURE_HOST_SUSPEND_TIME and MSR_KVM_HOST_SUSPEND_TIME Hikaru Nishida
2021-08-06 10:07 ` [v2 PATCH 2/4] x86/kvm: Add definitions for virtual suspend time injection Hikaru Nishida
2021-08-10 15:14   ` Thomas Gleixner
2021-08-13 18:36   ` Guenter Roeck
2021-08-06 10:07 ` [v2 PATCH 3/4] x86/kvm: Add host side support " Hikaru Nishida
2021-08-10 15:21   ` Thomas Gleixner [this message]
2021-08-10 15:24   ` Thomas Gleixner
2021-08-14  7:22   ` Paolo Bonzini
2021-08-18  9:32     ` Vitaly Kuznetsov
2021-08-18 20:49       ` Paolo Bonzini
2021-08-06 10:07 ` [v2 PATCH 4/4] x86/kvm: Add guest " Hikaru Nishida
2021-08-10 15:48   ` Thomas Gleixner

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