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xen/events: Support event channel rebind on ARM

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Currently, the event channel rebind code is gated with the presence of
the vector callback.

The virtual interrupt controller on ARM has the concept of per-CPU
interrupt (PPI) which allow us to support per-VCPU event channel.
Therefore there is no need of vector callback for ARM.

Xen is already using a free PPI to notify the guest VCPU of an event.
Furthermore, the xen code initialization in Linux (see
arch/arm/xen/enlighten.c) is requesting correctly a per-CPU IRQ.

Introduce new helper xen_support_evtchn_rebind to allow architecture
decide whether rebind an event is support or not. It will always return
true on ARM and keep the same behavior on x86.

This is also allow us to drop the usage of xen_have_vector_callback
entirely in the ARM code.

Signed-off-by: Julien Grall <julien.grall@citrix.com>
Signed-off-by: David Vrabel <david.vrabel@citrix.com>
This commit is contained in:
Julien Grall
2015-07-28 10:10:42 +01:00
committed by David Vrabel
parent 907c3eb18e
commit 4a5b69464e
6 changed files with 24 additions and 10 deletions
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11
arch/x86/include/asm/xen/events.h
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@@ -20,4 +20,15 @@ static inline int xen_irqs_disabled(struct pt_regs *regs)
/* No need for a barrier -- XCHG is a barrier on x86. */
#define xchg_xen_ulong(ptr, val) xchg((ptr), (val))
extern int xen_have_vector_callback;
/*
* Events delivered via platform PCI interrupts are always
* routed to vcpu 0 and hence cannot be rebound.
*/
static inline bool xen_support_evtchn_rebind(void)
{
return (!xen_hvm_domain() || xen_have_vector_callback);
}
#endif /* _ASM_X86_XEN_EVENTS_H */