Re: [PATCH V6 05/10] xen/arm64: gicv3: Use AFF1 when translating ICC_SGI1R_EL1 to cpumask

From: Julien Grall <julien.grall@citrix.com>
To: Ian Campbell <ian.campbell@citrix.com>, Chen Baozi <cbz@baozis.org>
Cc: Julien Grall <julien.grall@citrix.com>,
	xen-devel@lists.xenproject.org, Chen Baozi <baozich@gmail.com>
Subject: Re: [PATCH V6 05/10] xen/arm64: gicv3: Use AFF1 when translating ICC_SGI1R_EL1 to cpumask
Date: Fri, 5 Jun 2015 19:25:32 +0100	[thread overview]
Message-ID: <5571E99C.9050803@citrix.com> (raw)
In-Reply-To: <1433520573.7108.337.camel@citrix.com>

On 05/06/2015 17:09, Ian Campbell wrote:
>> +         * injection, ignoring level 2 & 3.
>> +         */
>> +        if ( gicv3_sgir_to_cpumask(&vcpu_mask, sgir) )
>> +        {
>> +            gprintk(XENLOG_WARNING, "Wrong affinity in SGI1R_EL register\n");
>
> I don't think we need to log this. The guest has asked to send an SGI to
> a VCPU which we know can't possibly exist. I'm not sure what real h/w
> would do, but if it is e.g. UNPREDICTABLE then we should consider
> killing the guest here. I suspect it's actually just ignored, in which
> case we can silently do the same.

 From the spec:

"Note: if a bit is one and the bit does not correspond to a valid target 
processor, the bit must be ignored by the Distributor. In such cases, a 
Distributor may optionally generate an SEI."

The implementation of SEI is implementation defined. I'm not sure what 
would be the right behavior to adopt here.

Regards,

-- 
Julien Grall