lkml.org 
[lkml]   [2019]   [Jan]   [21]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH 4.20 040/111] xen: Fix x86 sched_clock() interface for xen
Date
4.20-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Juergen Gross <jgross@suse.com>

commit 867cefb4cb1012f42cada1c7d1f35ac8dd276071 upstream.

Commit f94c8d11699759 ("sched/clock, x86/tsc: Rework the x86 'unstable'
sched_clock() interface") broke Xen guest time handling across
migration:

[ 187.249951] Freezing user space processes ... (elapsed 0.001 seconds) done.
[ 187.251137] OOM killer disabled.
[ 187.251137] Freezing remaining freezable tasks ... (elapsed 0.001 seconds) done.
[ 187.252299] suspending xenstore...
[ 187.266987] xen:grant_table: Grant tables using version 1 layout
[18446743811.706476] OOM killer enabled.
[18446743811.706478] Restarting tasks ... done.
[18446743811.720505] Setting capacity to 16777216

Fix that by setting xen_sched_clock_offset at resume time to ensure a
monotonic clock value.

[boris: replaced pr_info() with pr_info_once() in xen_callback_vector()
to avoid printing with incorrect timestamp during resume (as we
haven't re-adjusted the clock yet)]

Fixes: f94c8d11699759 ("sched/clock, x86/tsc: Rework the x86 'unstable' sched_clock() interface")
Cc: <stable@vger.kernel.org> # 4.11
Reported-by: Hans van Kranenburg <hans.van.kranenburg@mendix.com>
Signed-off-by: Juergen Gross <jgross@suse.com>
Tested-by: Hans van Kranenburg <hans.van.kranenburg@mendix.com>
Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
arch/x86/xen/time.c | 12 +++++++++---
drivers/xen/events/events_base.c | 2 +-
2 files changed, 10 insertions(+), 4 deletions(-)

--- a/arch/x86/xen/time.c
+++ b/arch/x86/xen/time.c
@@ -361,8 +361,6 @@ void xen_timer_resume(void)
{
int cpu;

- pvclock_resume();
-
if (xen_clockevent != &xen_vcpuop_clockevent)
return;

@@ -379,12 +377,15 @@ static const struct pv_time_ops xen_time
};

static struct pvclock_vsyscall_time_info *xen_clock __read_mostly;
+static u64 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;
+
if (!xen_clock)
return;

@@ -404,7 +405,7 @@ void xen_restore_time_memory_area(void)
int ret;

if (!xen_clock)
- return;
+ goto out;

t.addr.v = &xen_clock->pvti;

@@ -421,6 +422,11 @@ void xen_restore_time_memory_area(void)
if (ret != 0)
pr_notice("Cannot restore secondary vcpu_time_info (err %d)",
ret);
+
+out:
+ /* Need pvclock_resume() before using xen_clocksource_read(). */
+ pvclock_resume();
+ xen_sched_clock_offset = xen_clocksource_read() - xen_clock_value_saved;
}

static void xen_setup_vsyscall_time_info(void)
--- a/drivers/xen/events/events_base.c
+++ b/drivers/xen/events/events_base.c
@@ -1650,7 +1650,7 @@ void xen_callback_vector(void)
xen_have_vector_callback = 0;
return;
}
- pr_info("Xen HVM callback vector for event delivery is enabled\n");
+ pr_info_once("Xen HVM callback vector for event delivery is enabled\n");
alloc_intr_gate(HYPERVISOR_CALLBACK_VECTOR,
xen_hvm_callback_vector);
}

\
 
 \ /
  Last update: 2019-01-21 15:21    [W:0.268 / U:6.368 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site