linux-kernel - [RFC PATCH 2/3] Add functions to check if the host has stopped the vm

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Date:	Wed,  3 Aug 2011 10:25:00 -0400
From:	Eric B Munson <emunson@...bm.net>
To:	kvm@...r.kernel.org
Cc:	kvm-ia64@...r.kernel.org, kvm-ppc@...r.kernel.org, avi@...hat.com,
	riel@...hat.com, glommer@...hat.com, linux-kernel@...r.kernel.org,
	aliguori@...ibm.com, raharper@...ibm.com,
	Eric B Munson <emunson@...bm.net>
Subject: [RFC PATCH 2/3] Add functions to check if the host has stopped the vm

When a host stops or suspends a VM it will set a flag to show this.  The
watchdog will use these functions to determine if a softlockup is real, or the
result of a suspended VM.

Signed-off-by: Eric B Munson <emunson@...bm.net>
---
 arch/x86/include/asm/pvclock.h |    3 +++
 arch/x86/kernel/kvmclock.c     |   12 ++++++++++++
 2 files changed, 15 insertions(+), 0 deletions(-)

diff --git a/arch/x86/include/asm/pvclock.h b/arch/x86/include/asm/pvclock.h
index a518c0a..a9e9b4f 100644
--- a/arch/x86/include/asm/pvclock.h
+++ b/arch/x86/include/asm/pvclock.h
@@ -13,6 +13,9 @@ void pvclock_read_wallclock(struct pvclock_wall_clock *wall,
 			    struct timespec *ts);
 void pvclock_resume(void);
 
+bool kvm_check_host_stopped(void);
+void kvm_clear_host_stopped(void);
+
 /*
  * Scale a 64-bit delta by scaling and multiplying by a 32-bit fraction,
  * yielding a 64-bit result.
diff --git a/arch/x86/kernel/kvmclock.c b/arch/x86/kernel/kvmclock.c
index c1a0188..5a42582 100644
--- a/arch/x86/kernel/kvmclock.c
+++ b/arch/x86/kernel/kvmclock.c
@@ -113,6 +113,18 @@ static void kvm_get_preset_lpj(void)
 	preset_lpj = lpj;
 }
 
+bool kvm_check_host_stopped()
+{
+	struct pvclock_vcpu_time_info *src = &per_cpu(hv_clock, 0);
+	return (src->flags & PVCLOCK_STOPPED) != 0;
+}
+
+void kvm_clear_host_stopped()
+{
+	struct pvclock_vcpu_time_info *src = &per_cpu(hv_clock, 0);
+	src->flags = src->flags & (~PVCLOCK_STOPPED);
+}
+
 static struct clocksource kvm_clock = {
 	.name = "kvm-clock",
 	.read = kvm_clock_get_cycles,
-- 
1.7.4.1

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