* [PATCH] xen/x86: Do not call xen_init_time_ops() until shared_info is initialized
@ 2017-05-03 20:20 Boris Ostrovsky
2017-05-04 6:37 ` Juergen Gross
2017-05-05 8:55 ` Juergen Gross
0 siblings, 2 replies; 3+ messages in thread
From: Boris Ostrovsky @ 2017-05-03 20:20 UTC (permalink / raw)
To: jgross; +Cc: xen-devel, linux-kernel, Boris Ostrovsky
Routines that are set by xen_init_time_ops() use shared_info's
pvclock_vcpu_time_info area. This area is not properly available until
shared_info is mapped in xen_setup_shared_info().
This became especially problematic due to commit dd759d93f4dd ("x86/timers:
Add simple udelay calibration") where we end up reading tsc_to_system_mul
from xen_dummy_shared_info (i.e. getting zero value) and then trying
to divide by it in pvclock_tsc_khz().
Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
---
arch/x86/xen/enlighten_pv.c | 9 +++++++--
arch/x86/xen/time.c | 2 +-
2 files changed, 8 insertions(+), 3 deletions(-)
diff --git a/arch/x86/xen/enlighten_pv.c b/arch/x86/xen/enlighten_pv.c
index a732bc2..6f80a01 100644
--- a/arch/x86/xen/enlighten_pv.c
+++ b/arch/x86/xen/enlighten_pv.c
@@ -988,6 +988,13 @@ void xen_setup_shared_info(void)
#endif
xen_setup_mfn_list_list();
+
+ /*
+ * Now that shared info is set up we can start using routines that
+ * point to pvclock area.
+ */
+ if (system_state == SYSTEM_BOOTING)
+ xen_init_time_ops();
}
/* This is called once we have the cpu_possible_mask */
@@ -1286,8 +1293,6 @@ asmlinkage __visible void __init xen_start_kernel(void)
x86_init.oem.arch_setup = xen_arch_setup;
x86_init.oem.banner = xen_banner;
- xen_init_time_ops();
-
/*
* Set up some pagetable state before starting to set any ptes.
*/
diff --git a/arch/x86/xen/time.c b/arch/x86/xen/time.c
index 090c7eb..a1895a8 100644
--- a/arch/x86/xen/time.c
+++ b/arch/x86/xen/time.c
@@ -406,7 +406,7 @@ static void __init xen_time_init(void)
pvclock_gtod_register_notifier(&xen_pvclock_gtod_notifier);
}
-void __init xen_init_time_ops(void)
+void __ref xen_init_time_ops(void)
{
pv_time_ops = xen_time_ops;
--
2.7.4
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH] xen/x86: Do not call xen_init_time_ops() until shared_info is initialized
2017-05-03 20:20 [PATCH] xen/x86: Do not call xen_init_time_ops() until shared_info is initialized Boris Ostrovsky
@ 2017-05-04 6:37 ` Juergen Gross
2017-05-05 8:55 ` Juergen Gross
1 sibling, 0 replies; 3+ messages in thread
From: Juergen Gross @ 2017-05-04 6:37 UTC (permalink / raw)
To: Boris Ostrovsky; +Cc: xen-devel, linux-kernel
On 03/05/17 22:20, Boris Ostrovsky wrote:
> Routines that are set by xen_init_time_ops() use shared_info's
> pvclock_vcpu_time_info area. This area is not properly available until
> shared_info is mapped in xen_setup_shared_info().
>
> This became especially problematic due to commit dd759d93f4dd ("x86/timers:
> Add simple udelay calibration") where we end up reading tsc_to_system_mul
> from xen_dummy_shared_info (i.e. getting zero value) and then trying
> to divide by it in pvclock_tsc_khz().
>
> Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Reviewed-by: Juergen Gross <jgross@suse.com>
Thanks,
Juergen
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] xen/x86: Do not call xen_init_time_ops() until shared_info is initialized
2017-05-03 20:20 [PATCH] xen/x86: Do not call xen_init_time_ops() until shared_info is initialized Boris Ostrovsky
2017-05-04 6:37 ` Juergen Gross
@ 2017-05-05 8:55 ` Juergen Gross
1 sibling, 0 replies; 3+ messages in thread
From: Juergen Gross @ 2017-05-05 8:55 UTC (permalink / raw)
To: Boris Ostrovsky; +Cc: xen-devel, linux-kernel
On 03/05/17 22:20, Boris Ostrovsky wrote:
> Routines that are set by xen_init_time_ops() use shared_info's
> pvclock_vcpu_time_info area. This area is not properly available until
> shared_info is mapped in xen_setup_shared_info().
>
> This became especially problematic due to commit dd759d93f4dd ("x86/timers:
> Add simple udelay calibration") where we end up reading tsc_to_system_mul
> from xen_dummy_shared_info (i.e. getting zero value) and then trying
> to divide by it in pvclock_tsc_khz().
>
> Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Pushed to xen/tip for-linus-4.12b
Thanks,
Juergen
^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2017-05-05 8:55 UTC | newest]
Thread overview: 3+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2017-05-03 20:20 [PATCH] xen/x86: Do not call xen_init_time_ops() until shared_info is initialized Boris Ostrovsky
2017-05-04 6:37 ` Juergen Gross
2017-05-05 8:55 ` Juergen Gross
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).