Re: [Xen-devel] [PATCH V2] x86/vm_event: block interrupt injection for sync vm_events

[Roger Pau Monné <roger.pau@xxxxxxxxxx>]

On Tue, Dec 11, 2018 at 12:01:53PM +0200, Razvan Cojocaru wrote:
> On 12/10/18 6:59 PM, Razvan Cojocaru wrote:
> > On 12/10/18 6:49 PM, Roger Pau Monné wrote:
> >> On Mon, Dec 10, 2018 at 06:01:49PM +0200, Razvan Cojocaru wrote:
> >>> diff --git a/xen/include/asm-arm/vm_event.h 
> >>> b/xen/include/asm-arm/vm_event.h
> >>> index 66f2474..b63249e 100644
> >>> --- a/xen/include/asm-arm/vm_event.h
> >>> +++ b/xen/include/asm-arm/vm_event.h
> >>> @@ -52,4 +52,10 @@ void vm_event_emulate_check(struct vcpu *v, 
> >>> vm_event_response_t *rsp)
> >>>      /* Not supported on ARM. */
> >>>  }
> >>>  
> >>> +static inline
> >>> +void vm_event_block_interrupts(struct vcpu *v, bool value)
> >>> +{
> >>> +    /* Not supported on ARM. */
> >>
> >> ASSERT_UNREACHABLE?
> > 
> > Will do (although if you look at the rest of the function in that header
> > it'll break what appears to be the prior convention).
> 
> Sorry, on second thought we can't do that, because that function is
> being called from the common code - which is why the function became
> necessary. Specifically, this it unconditionally called in
> monitor_traps(), which is used for all events (ARM and otherwise).
> 
> So it's valid to call monitor_traps() for ARM vm_events and expect it to
> run without issue, which ASSERT_UNREACHABLE() would of course break.

But then the functionality that makes use of vm_event_block_interrupts
cannot work reliably on ARM and should not be used?

Thanks, Roger.

_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxxx
https://lists.xenproject.org/mailman/listinfo/xen-devel