Re: [PATCH v3 16/16] xen/arm: add SGI handling for GICv3

[Julien Grall <julien.grall@linaro.org>]

On 05/02/2014 01:57 PM, Vijay Kilari wrote:
> On Sat, Apr 19, 2014 at 1:50 AM, Julien Grall <julien.grall@linaro.org> wrote:
>> Hello Vijaya,
>>
>>
>> On 15/04/14 12:17, vijay.kilari@gmail.com wrote:
>>>
>>> From: Vijaya Kumar K <Vijaya.Kumar@caviumnetworks.com>
>>>
>>> In ARMv8, write to ICC_SGI1R_EL1 register raises trap to EL2.
>>> Handle the trap and inject SGI to vcpu.
>>>
>>>   /* The base of the stack must always be double-word aligned, which means
>>>    * that both the kernel half of struct cpu_user_regs (which is pushed in
>>> @@ -1406,6 +1407,14 @@ static void do_sysreg(struct cpu_user_regs *regs,
>>>               domain_crash_synchronous();
>>>           }
>>>           break;
>>> +    case HSR_SYSREG_ICC_SGI1R_EL1:
>>
>>
>> Any reason to not trap ICC_SGI0R_EL1 and ICC_ASGI1R_EL1?
> 
> Does Xen supports Secure guests?. In any case, I can make a check on GICR_NSACR
> and reject if generating non-secure writes are permitted to generate
> secure grp0 interrupts.
> Similarly for ICC_ASG1R_EL1.

It's not possible to have secure guest. Are you sure it will never trap
to Xen if the guest try to generate a Group 1 SGIs to a secure state?
(see ICC_ASGI1R_EL1).

>>
>>
>>> +        if ( !vgic_emulate(regs, hsr) )
>>> +        {
>>> +            dprintk(XENLOG_ERR,
>>> +                    "failed emulation of 64-bit vgic sysreg access\n");
>>> +            domain_crash_synchronous();
>>
>>
>> So, you crash the domain if the SGI is not handled??? The GICv3 spec
>> requests a specific behavior.
> 
>    Can you please point to GICv3 spec that request specific behavior
> to handle this scenario?

6.5.1: "Read-Only and Write-Only System Register Accesses"

You should inject an UNDEF exception.

Regards,

-- 
Julien Grall