[Xen-devel] Re: Fix "Many lost ticks" warning in ia32e guest

[Horms <horms@xxxxxxxxxxxx>]

Minor comment inline.

-- 
Horms                                           
  H: http://www.vergenet.net/~horms/
  W: http://www.valinux.co.jp/en/

On Mon, 10 Jul 2006 14:54:21 +0800, Yang, Xiaowei wrote:
> [-- text/plain, encoding quoted-printable, charset: us-ascii, 11 lines --]
> 
> Keir,
> This patch fixes "Many lost ticks" warning in ia32e guest. 
> New i8254.c code in HV has some problem calculating PIT counter. So when
> guest kernel reads it and uses it to adjust last_tsc when PIT is
> generated, it may think there are more than two ticks of time passed
> between 2 continuous PIT, which ended up with "Warning: Many lost
> ticks".
> 
> Thanks,
> Xiaowei
> 
> 
> Fix "Many lost ticks" warning in ia32e guest
> 
> Signed-off-by: Eddie Dong <eddie.dong@xxxxxxxxx>
> Signed-off-by: Xiaowei Yang <xiaowei.yang@xxxxxxxxx>
> 
> diff -r fd6d12935b56 xen/arch/x86/hvm/i8254.c
> --- a/xen/arch/x86/hvm/i8254.c        Mon Jul  3 15:07:20 2006
> +++ b/xen/arch/x86/hvm/i8254.c        Mon Jul 10 11:23:14 2006
> @@ -188,6 +188,12 @@
>      return s->gate;
>  }
>  
> +void pit_time_fired(struct vcpu *v, void *priv)
> +{
> +    PITChannelState *s = priv;
> +    s->count_load_time = hvm_get_clock(v);
> +}
> +
>  static inline void pit_load_count(PITChannelState *s, int val)
>  {
>      u32   period;
> @@ -209,11 +215,11 @@
>      switch (s->mode) {
>          case 2:
>              /* create periodic time */
> -            s->pt = create_periodic_time (s->vcpu, period, 0, 0);
> +            s->pt = create_periodic_time (s, period, 0, 0);
>              break;
>          case 1:
>              /* create one shot time */
> -            s->pt = create_periodic_time (s->vcpu, period, 0, 1);
> +            s->pt = create_periodic_time (s, period, 0, 1);
>  #ifdef DEBUG_PIT
>              printk("HVM_PIT: create one shot time.\n");
>  #endif
> diff -r fd6d12935b56 xen/arch/x86/hvm/intercept.c
> --- a/xen/arch/x86/hvm/intercept.c    Mon Jul  3 15:07:20 2006
> +++ b/xen/arch/x86/hvm/intercept.c    Mon Jul 10 11:23:14 2006
> @@ -261,11 +261,12 @@
>   * period: fire frequency in ns.
>   */
>  struct periodic_time * create_periodic_time(
> -        struct vcpu *v, 
> +        PITChannelState *s,
>          u32 period, 
>          char irq,
>          char one_shot)
>  {
> +    struct vcpu *v = s->vcpu;
>      struct periodic_time *pt = 
> &(v->domain->arch.hvm_domain.pl_time.periodic_tm);
>      if ( pt->enabled ) {
>          if ( v->vcpu_id != 0 ) {
> @@ -290,6 +291,7 @@
>      pt->scheduled = NOW() + period;
>      set_timer (&pt->timer,pt->scheduled);
>      pt->enabled = 1;
> +    pt->priv = s;
>      return pt;
>  }
>  
> diff -r fd6d12935b56 xen/arch/x86/hvm/vmx/io.c
> --- a/xen/arch/x86/hvm/vmx/io.c       Mon Jul  3 15:07:20 2006
> +++ b/xen/arch/x86/hvm/vmx/io.c       Mon Jul 10 11:23:14 2006
> @@ -75,6 +75,7 @@
>              pt->pending_intr_nr--;
>              pt->last_plt_gtime += pt->period_cycles;
>              set_guest_time(v, pt->last_plt_gtime);
> +            pit_time_fired(v, pt->priv);
>          }
>      }
>  
> diff -r fd6d12935b56 xen/include/asm-x86/hvm/vpit.h
> --- a/xen/include/asm-x86/hvm/vpit.h  Mon Jul  3 15:07:20 2006
> +++ b/xen/include/asm-x86/hvm/vpit.h  Mon Jul 10 11:23:14 2006
> @@ -64,6 +64,7 @@
>      s_time_t scheduled;         /* scheduled timer interrupt */
>      u64 last_plt_gtime;         /* platform time when last IRQ is injected */
>      struct timer timer;         /* ac_timer */
> +    void *priv;                 /* ponit back to platform time source */
>  };
>  
>  typedef struct PITState {
> @@ -93,9 +94,10 @@
>  extern void hvm_hooks_assist(struct vcpu *v);
>  extern void pickup_deactive_ticks(struct periodic_time *vpit);
>  extern u64 hvm_get_guest_time(struct vcpu *v);
> -extern struct periodic_time *create_periodic_time(struct vcpu *v, u32 
> period, char irq, char one_shot);
> +extern struct periodic_time *create_periodic_time(PITChannelState *v, u32 
> period, char irq, char one_shot);

Could this line be <=80 characters wide?

>  extern void destroy_periodic_time(struct periodic_time *pt);
>  void pit_init(struct vcpu *v, unsigned long cpu_khz);
>  void pt_timer_fn(void *data);
> +void pit_time_fired(struct vcpu *v, void *priv);
>  
>  #endif /* __ASM_X86_HVM_VPIT_H__ */


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