Re: [Xen-devel] [PATCH V4 5/5] xen: remove evtchn_upcall_mask from interface on ARM

[Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>]

On Tue, 23 Apr 2013, Ian Campbell wrote:
> On ARM event-channel upcalls are masked using the hardware's interrupt mask
> bit and not by a software bit.
> 
> Leaving this field present in the interface has caused some confusion already
> and is liable to mean it gets inadvertently used in the future. So arrange for
> this field to be turned into a padding field on ARM by introducing a
> XEN_HAVE_PV_UPCALL_MASK define.
> 
> This bit is also unused for x86 PV-on-HVM guests, but we can't realistically
> distinguish those from x86 PV guests in the headers.
> 
> Add a per-arch vcpu_event_delivery_is_enabled function to replace the single
> open coded use of evtchn_upcall_mask in common code (in a debug keyhandler).
> The existing local_event_delivery_is_enabled, which operates only on current,
> was unimplemented on ARM and unused on x86, so remove it.
> 
> Signed-off-by: Ian Campbell <ian.campbell@xxxxxxxxxx>
> Cc: keir@xxxxxxx
> Cc: jbeulich@xxxxxxx
> ---
> This patch build on top of Stefano's "xen/arm: trap guest WFI" patch.

Acked-by: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>


>  xen/common/keyhandler.c           |    2 +-
>  xen/include/asm-arm/event.h       |   13 +++++++------
>  xen/include/asm-x86/event.h       |   10 +++++-----
>  xen/include/public/arch-x86/xen.h |    3 +++
>  xen/include/public/xen.h          |    4 ++++
>  5 files changed, 20 insertions(+), 12 deletions(-)
> 
> diff --git a/xen/common/keyhandler.c b/xen/common/keyhandler.c
> index 5072133..5725f90 100644
> --- a/xen/common/keyhandler.c
> +++ b/xen/common/keyhandler.c
> @@ -293,7 +293,7 @@ static void dump_domains(unsigned char key)
>                     v->vcpu_id, v->processor,
>                     v->is_running ? 'T':'F', v->poll_evtchn,
>                     vcpu_info(v, evtchn_upcall_pending),
> -                   vcpu_info(v, evtchn_upcall_mask));
> +                   !vcpu_event_delivery_is_enabled(v));
>              cpuset_print(tmpstr, sizeof(tmpstr), v->vcpu_dirty_cpumask);
>              printk("dirty_cpus=%s ", tmpstr);
>              cpuset_print(tmpstr, sizeof(tmpstr), v->cpu_affinity);
> diff --git a/xen/include/asm-arm/event.h b/xen/include/asm-arm/event.h
> index 276fef5..0f04ee1 100644
> --- a/xen/include/asm-arm/event.h
> +++ b/xen/include/asm-arm/event.h
> @@ -7,6 +7,12 @@
>  void vcpu_kick(struct vcpu *v);
>  void vcpu_mark_events_pending(struct vcpu *v);
>  
> +static inline int vcpu_event_delivery_is_enabled(struct vcpu *v)
> +{
> +    struct cpu_user_regs *regs = &v->arch.cpu_info->guest_cpu_user_regs;
> +    return !(regs->cpsr & PSR_IRQ_MASK);
> +}
> +
>  static inline int local_events_need_delivery_nomask(void)
>  {
>      struct pending_irq *p = irq_to_pending(current, 
> VGIC_IRQ_EVTCHN_CALLBACK);
> @@ -31,16 +37,11 @@ static inline int local_events_need_delivery_nomask(void)
>  
>  static inline int local_events_need_delivery(void)
>  {
> -    struct cpu_user_regs *regs = guest_cpu_user_regs();
> -
> -    /* guest IRQs are masked */
> -    if ( (regs->cpsr & PSR_IRQ_MASK) )
> +    if ( !vcpu_event_delivery_is_enabled(current) )
>          return 0;
>      return local_events_need_delivery_nomask();
>  }
>  
> -int local_event_delivery_is_enabled(void);
> -
>  static inline void local_event_delivery_enable(void)
>  {
>      struct cpu_user_regs *regs = guest_cpu_user_regs();
> diff --git a/xen/include/asm-x86/event.h b/xen/include/asm-x86/event.h
> index 06057c7..7edeb5b 100644
> --- a/xen/include/asm-x86/event.h
> +++ b/xen/include/asm-x86/event.h
> @@ -14,6 +14,11 @@
>  void vcpu_kick(struct vcpu *v);
>  void vcpu_mark_events_pending(struct vcpu *v);
>  
> +static inline int vcpu_event_delivery_is_enabled(struct vcpu *v)
> +{
> +    return !vcpu_info(v, evtchn_upcall_mask);
> +}
> +
>  int hvm_local_events_need_delivery(struct vcpu *v);
>  static inline int local_events_need_delivery(void)
>  {
> @@ -23,11 +28,6 @@ static inline int local_events_need_delivery(void)
>               !vcpu_info(v, evtchn_upcall_mask)));
>  }
>  
> -static inline int local_event_delivery_is_enabled(void)
> -{
> -    return !vcpu_info(current, evtchn_upcall_mask);
> -}
> -
>  static inline void local_event_delivery_disable(void)
>  {
>      vcpu_info(current, evtchn_upcall_mask) = 1;
> diff --git a/xen/include/public/arch-x86/xen.h 
> b/xen/include/public/arch-x86/xen.h
> index c528e91..5c4b08e 100644
> --- a/xen/include/public/arch-x86/xen.h
> +++ b/xen/include/public/arch-x86/xen.h
> @@ -73,6 +73,9 @@ typedef unsigned long xen_pfn_t;
>  #define XEN_HAVE_PV_GUEST_ENTRY 1
>  #define COMPAT_HAVE_PV_GUEST_ENTRY 1
>  
> +#define XEN_HAVE_PV_UPCALL_MASK 1
> +#define COMPAT_HAVE_PV_UPCALL_MASK 1
> +
>  /*
>   * `incontents 200 segdesc Segment Descriptor Tables
>   */
> diff --git a/xen/include/public/xen.h b/xen/include/public/xen.h
> index 037540d..2a40970 100644
> --- a/xen/include/public/xen.h
> +++ b/xen/include/public/xen.h
> @@ -612,7 +612,11 @@ struct vcpu_info {
>       * to block: this avoids wakeup-waiting races.
>       */
>      uint8_t evtchn_upcall_pending;
> +#ifdef XEN_HAVE_PV_UPCALL_MASK
>      uint8_t evtchn_upcall_mask;
> +#else /* XEN_HAVE_PV_UPCALL_MASK */
> +    uint8_t pad0;
> +#endif /* XEN_HAVE_PV_UPCALL_MASK */
>      xen_ulong_t evtchn_pending_sel;
>      struct arch_vcpu_info arch;
>      struct vcpu_time_info time;
> -- 
> 1.7.2.5
> 

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