linux-kernel - Re: [PATCH v2 1/3] KVM: Introduce kvm_total_suspend

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Message-ID: <ZsV9wDXDoUMSNWgm@intel.com>
Date: Wed, 21 Aug 2024 13:40:16 +0800
From: Chao Gao <chao.gao@...el.com>
To: Suleiman Souhlal <suleiman@...gle.com>
CC: Paolo Bonzini <pbonzini@...hat.com>, Sean Christopherson
	<seanjc@...gle.com>, Thomas Gleixner <tglx@...utronix.de>, Ingo Molnar
	<mingo@...hat.com>, Borislav Petkov <bp@...en8.de>, Dave Hansen
	<dave.hansen@...ux.intel.com>, <x86@...nel.org>, "H. Peter Anvin"
	<hpa@...or.com>, <kvm@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
	<ssouhlal@...ebsd.org>
Subject: Re: [PATCH v2 1/3] KVM: Introduce kvm_total_suspend_ns().

On Tue, Aug 20, 2024 at 01:35:41PM +0900, Suleiman Souhlal wrote:
>It returns the cumulative nanoseconds that the host has been suspended.
>It is intended to be used for reporting host suspend time to the guest.
>
>Signed-off-by: Suleiman Souhlal <suleiman@...gle.com>

Reviewed-by: Chao Gao <chao.gao@...el.com>

one nit below

>---
> include/linux/kvm_host.h |  2 ++
> virt/kvm/kvm_main.c      | 13 +++++++++++++
> 2 files changed, 15 insertions(+)
>
>diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
>index b23c6d48392f7c..8fec37b372d8c0 100644
>--- a/include/linux/kvm_host.h
>+++ b/include/linux/kvm_host.h
>@@ -2494,4 +2494,6 @@ long kvm_arch_vcpu_pre_fault_memory(struct kvm_vcpu *vcpu,
> 				    struct kvm_pre_fault_memory *range);
> #endif
> 
>+u64 kvm_total_suspend_ns(void);
>+
> #endif
>diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
>index cb2b78e92910fb..2235933d9247bc 100644
>--- a/virt/kvm/kvm_main.c
>+++ b/virt/kvm/kvm_main.c
>@@ -5720,6 +5720,15 @@ static void kvm_shutdown(void)
> 	on_each_cpu(hardware_disable_nolock, NULL, 1);
> }
> 
>+static u64 last_suspend;
>+static u64 total_suspend_ns;
>+
>+u64
>+kvm_total_suspend_ns(void)

nit: don't wrap before the function name.

>+{
>+	return total_suspend_ns;
>+}
>+
> static int kvm_suspend(void)
> {
> 	/*
>@@ -5735,6 +5744,8 @@ static int kvm_suspend(void)
> 
> 	if (kvm_usage_count)
> 		hardware_disable_nolock(NULL);
>+
>+	last_suspend = ktime_get_boottime_ns();
> 	return 0;
> }
> 
>@@ -5745,6 +5756,8 @@ static void kvm_resume(void)
> 
> 	if (kvm_usage_count)
> 		WARN_ON_ONCE(__hardware_enable_nolock());
>+
>+	total_suspend_ns += ktime_get_boottime_ns() - last_suspend;
> }
> 
> static struct syscore_ops kvm_syscore_ops = {
>-- 
>2.46.0.184.g6999bdac58-goog
>