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* [Xen-devel] [RFC PATCH v3 10/12] xen: Introduce wrapper for save/restore sched clock offset
@ 2020-02-12 22:34 Anchal Agarwal
  0 siblings, 0 replies; 2+ messages in thread
From: Anchal Agarwal @ 2020-02-12 22:34 UTC (permalink / raw)
  To: tglx, mingo, bp, hpa, x86, boris.ostrovsky, jgross, linux-pm,
	linux-mm, kamatam, sstabellini, konrad.wilk, roger.pau, axboe,
	davem, rjw, len.brown, pavel, peterz, eduval, sblbir, anchalag,
	xen-devel, vkuznets, netdev, linux-kernel, dwmw, fllinden, benh

Introduce wrappers for save/restore xen_sched_clock_offset to be
used by PM hibernation code to avoid system instability during resume.

Signed-off-by: Anchal Agarwal <anchalag@amazon.com>

---
Changes since V2:
* Dropped marking tsc unstable during hibernation patch
* Fixed issue with xen_sched_clock_offset during suspend/resume
* On further interrogation and testing, the issue wasn't with tsc
being stable/unstable

---
 arch/x86/xen/time.c    | 15 +++++++++++++--
 arch/x86/xen/xen-ops.h |  2 ++
 2 files changed, 15 insertions(+), 2 deletions(-)

diff --git a/arch/x86/xen/time.c b/arch/x86/xen/time.c
index 8cf632dda605..eeb6d3d2eaab 100644
--- a/arch/x86/xen/time.c
+++ b/arch/x86/xen/time.c
@@ -379,12 +379,23 @@ static const struct pv_time_ops xen_time_ops __initconst = {
 static struct pvclock_vsyscall_time_info *xen_clock __read_mostly;
 static u64 xen_clock_value_saved;
 
+/*This is needed to maintain a monotonic clock value during PM hibernation */
+void xen_save_sched_clock_offset(void)
+{
+	xen_clock_value_saved = xen_clocksource_read() - xen_sched_clock_offset;
+}
+
+void xen_restore_sched_clock_offset(void)
+{
+	xen_sched_clock_offset = xen_clocksource_read() - xen_clock_value_saved;
+}
+
 void xen_save_time_memory_area(void)
 {
 	struct vcpu_register_time_memory_area t;
 	int ret;
 
-	xen_clock_value_saved = xen_clocksource_read() - xen_sched_clock_offset;
+	xen_save_sched_clock_offset();
 
 	if (!xen_clock)
 		return;
@@ -426,7 +437,7 @@ void xen_restore_time_memory_area(void)
 out:
 	/* Need pvclock_resume() before using xen_clocksource_read(). */
 	pvclock_resume();
-	xen_sched_clock_offset = xen_clocksource_read() - xen_clock_value_saved;
+	xen_restore_sched_clock_offset();
 }
 
 static void xen_setup_vsyscall_time_info(void)
diff --git a/arch/x86/xen/xen-ops.h b/arch/x86/xen/xen-ops.h
index d84c357994bd..9f49124df033 100644
--- a/arch/x86/xen/xen-ops.h
+++ b/arch/x86/xen/xen-ops.h
@@ -72,6 +72,8 @@ void xen_save_time_memory_area(void);
 void xen_restore_time_memory_area(void);
 void xen_init_time_ops(void);
 void xen_hvm_init_time_ops(void);
+void xen_save_sched_clock_offset(void);
+void xen_restore_sched_clock_offset(void);
 
 irqreturn_t xen_debug_interrupt(int irq, void *dev_id);
 
-- 
2.24.1.AMZN


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Xen-devel@lists.xenproject.org
https://lists.xenproject.org/mailman/listinfo/xen-devel

^ permalink raw reply	[flat|nested] 2+ messages in thread

* [Xen-devel] [RFC PATCH v3 10/12] xen: Introduce wrapper for save/restore sched clock offset
  2020-02-14 23:21 [Xen-devel] [RFC RESEND PATCH v3 00/12] Enable PM hibernation on guest VMs Anchal Agarwal
@ 2020-02-14 23:27 ` Anchal Agarwal
  0 siblings, 0 replies; 2+ messages in thread
From: Anchal Agarwal @ 2020-02-14 23:27 UTC (permalink / raw)
  To: tglx, mingo, bp, hpa, x86, boris.ostrovsky, jgross, linux-pm,
	linux-mm, kamatam, sstabellini, konrad.wilk, roger.pau, axboe,
	davem, rjw, len.brown, pavel, peterz, eduval, sblbir, anchalag,
	xen-devel, vkuznets, netdev, linux-kernel, dwmw, fllinden, benh

Introduce wrappers for save/restore xen_sched_clock_offset to be
used by PM hibernation code to avoid system instability during resume.

Signed-off-by: Anchal Agarwal <anchalag@amazon.com>
---
 arch/x86/xen/time.c    | 15 +++++++++++++--
 arch/x86/xen/xen-ops.h |  2 ++
 2 files changed, 15 insertions(+), 2 deletions(-)

diff --git a/arch/x86/xen/time.c b/arch/x86/xen/time.c
index 8cf632dda605..eeb6d3d2eaab 100644
--- a/arch/x86/xen/time.c
+++ b/arch/x86/xen/time.c
@@ -379,12 +379,23 @@ static const struct pv_time_ops xen_time_ops __initconst = {
 static struct pvclock_vsyscall_time_info *xen_clock __read_mostly;
 static u64 xen_clock_value_saved;
 
+/*This is needed to maintain a monotonic clock value during PM hibernation */
+void xen_save_sched_clock_offset(void)
+{
+	xen_clock_value_saved = xen_clocksource_read() - xen_sched_clock_offset;
+}
+
+void xen_restore_sched_clock_offset(void)
+{
+	xen_sched_clock_offset = xen_clocksource_read() - xen_clock_value_saved;
+}
+
 void xen_save_time_memory_area(void)
 {
 	struct vcpu_register_time_memory_area t;
 	int ret;
 
-	xen_clock_value_saved = xen_clocksource_read() - xen_sched_clock_offset;
+	xen_save_sched_clock_offset();
 
 	if (!xen_clock)
 		return;
@@ -426,7 +437,7 @@ void xen_restore_time_memory_area(void)
 out:
 	/* Need pvclock_resume() before using xen_clocksource_read(). */
 	pvclock_resume();
-	xen_sched_clock_offset = xen_clocksource_read() - xen_clock_value_saved;
+	xen_restore_sched_clock_offset();
 }
 
 static void xen_setup_vsyscall_time_info(void)
diff --git a/arch/x86/xen/xen-ops.h b/arch/x86/xen/xen-ops.h
index d84c357994bd..9f49124df033 100644
--- a/arch/x86/xen/xen-ops.h
+++ b/arch/x86/xen/xen-ops.h
@@ -72,6 +72,8 @@ void xen_save_time_memory_area(void);
 void xen_restore_time_memory_area(void);
 void xen_init_time_ops(void);
 void xen_hvm_init_time_ops(void);
+void xen_save_sched_clock_offset(void);
+void xen_restore_sched_clock_offset(void);
 
 irqreturn_t xen_debug_interrupt(int irq, void *dev_id);
 
-- 
2.24.1.AMZN


_______________________________________________
Xen-devel mailing list
Xen-devel@lists.xenproject.org
https://lists.xenproject.org/mailman/listinfo/xen-devel

^ permalink raw reply	[flat|nested] 2+ messages in thread

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Thread overview: 2+ messages (download: mbox.gz / follow: Atom feed)
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2020-02-12 22:34 [Xen-devel] [RFC PATCH v3 10/12] xen: Introduce wrapper for save/restore sched clock offset Anchal Agarwal
2020-02-14 23:21 [Xen-devel] [RFC RESEND PATCH v3 00/12] Enable PM hibernation on guest VMs Anchal Agarwal
2020-02-14 23:27 ` [Xen-devel] [RFC PATCH v3 10/12] xen: Introduce wrapper for save/restore sched clock offset Anchal Agarwal

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