Re: [PATCH] x86/MSI: fix guest unmasking when handling IRQ via event channel

["Jan Beulich" <JBeulich@suse.com>]

>>> On 08.07.15 at 11:39, <david.vrabel@citrix.com> wrote:
> On 08/07/15 09:56, Jan Beulich wrote:
>> Rather than assuming only PV guests need special treatment (and
>> dealing with that directly when an IRQ gets set up), keep all guest MSI
>> IRQs masked until either the (HVM) guest unmasks them via vMSI or the
>> (PV, PVHVM, or PVH) guest sets up an event channel for it.
>> 
>> To not further clutter the common evtchn_bind_pirq() with x86-specific
>> code, introduce an arch_evtchn_bind_pirq() hook instead.
> 
> Can you describe the symptoms of the bug being fixed here?

Interrupts simply didn't get unmasked for PVHVM Linux guests.

>> --- a/xen/include/asm-arm/irq.h
>> +++ b/xen/include/asm-arm/irq.h
>> @@ -47,6 +47,8 @@ int release_guest_irq(struct domain *d, 
>>  
>>  void arch_move_irqs(struct vcpu *v);
>>  
>> +#define arch_evtchn_bind_pirq(d, pirq) ((void)((d) + (pirq)))
> 
> Would this be better as a inline function?
> 
>> +
>>  /* Set IRQ type for an SPI */
>>  int irq_set_spi_type(unsigned int spi, unsigned int type);
>>  
>> --- a/xen/include/xen/irq.h
>> +++ b/xen/include/xen/irq.h
>> @@ -172,4 +172,8 @@ unsigned int set_desc_affinity(struct ir
>>  unsigned int arch_hwdom_irqs(domid_t);
>>  #endif
>>  
>> +#ifndef arch_evtchn_bind_pirq
>> +void arch_evtchn_bind_pirq(struct domain *, int pirq);
> 
> ... moving this into xen/include/asm-x86/irq.h

Oh, right, (also to Julien) - this is exactly the reason I do not want it
to be an inline function for ARM: I want the declaration here, not
replicated in every interested arch's header.

Jan