Xen devel - Nov 2013 - [PATCH] hvm: reset TSC to 0 after domain resume from S3

Host S3 implicitly resets the host TSC to 0, but the tsc offset for hvm domains
is not recalculated
when they resume, causing it to go into negative values. In Linux guest using
tsc clocksource, this
results in a hang after wrap back to positive values since the tsc clocksource
implementation
expects it reset.

Signed-off-by: Tomasz Wroblewski <tomasz.wroblewski@citrix.com>
---
 xen/arch/x86/hvm/hvm.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/xen/arch/x86/hvm/hvm.c b/xen/arch/x86/hvm/hvm.c
index 3b353ec..3d48978 100644
--- a/xen/arch/x86/hvm/hvm.c
+++ b/xen/arch/x86/hvm/hvm.c
@@ -3736,8 +3736,13 @@ static void hvm_s3_suspend(struct domain *d)
 
 static void hvm_s3_resume(struct domain *d)
 {
+    struct vcpu *v;
     if ( test_and_clear_bool(d->arch.hvm_domain.is_s3_suspended) )
+    {
+        for_each_vcpu( d, v )
+            hvm_set_guest_tsc( v, 0 );
         domain_unpause(d);
+    }
 }
 
 static int hvmop_set_isa_irq_level(
-- 
1.8.4.rc3

>>> On 20.11.13 at 15:22, Tomasz Wroblewski
<tomasz.wroblewski@citrix.com> wrote:
> --- a/xen/arch/x86/hvm/hvm.c
> +++ b/xen/arch/x86/hvm/hvm.c
> @@ -3736,8 +3736,13 @@ static void hvm_s3_suspend(struct domain *d)
>  
>  static void hvm_s3_resume(struct domain *d)
>  {
> +    struct vcpu *v;
Blank line needed here.

And it would imo be better to move the declaration inside the body
of the if().
>      if ( test_and_clear_bool(d->arch.hvm_domain.is_s3_suspended) )
> +    {
> +        for_each_vcpu( d, v )
> +            hvm_set_guest_tsc( v, 0 );
Stray blanks inside the parentheses.

(If I''m ending up committing this, and if no other need to redo
the patch shows up, I can take care of these cosmetics on the
fly, i.e. no need to send a v2 just for this.)

Jan

> (If I''m ending up committing this, and if no other need to redo
> the patch shows up, I can take care of these cosmetics on the
> fly, i.e. no need to send a v2 just for this.)
>
All right, thanks! Sorry for the blanks, I post patches infrequently enough to
forget the precise rules but frequently enough to delude
myself I still remember them.
> Jan
>