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@google.com>
---
 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)
+{
+	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

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@google.com>

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

On Wed, Aug 21, 2024 at 2:40 PM Chao Gao <chao.gao@intel.com> wrote:
>
> 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@google.com>
>
> Reviewed-by: Chao Gao <chao.gao@intel.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.

Sorry, I completely missed that, even after Sean told me.
Force of habit (FreeBSD style(9) says you have to do it).

If I send another version I will fix that.

-- Suleiman