Re: [PATCH v3 17/17] libxl/arm: Initialize domain param HVM_PARAM_CALLBACK_IRQ

From: Shannon Zhao <zhaoshenglong@huawei.com>
To: Julien Grall <julien.grall@arm.com>, Wei Liu <wei.liu2@citrix.com>
Cc: hangaohuai@huawei.com, sstabellini@kernel.org,
	ian.jackson@eu.citrix.com, peter.huangpeng@huawei.com,
	xen-devel@lists.xen.org, shannon.zhao@linaro.org,
	boris.ostrovsky@oracle.com
Subject: Re: [PATCH v3 17/17] libxl/arm: Initialize domain param HVM_PARAM_CALLBACK_IRQ
Date: Fri, 8 Jul 2016 11:41:42 +0800	[thread overview]
Message-ID: <577F20F6.1060203@huawei.com> (raw)
In-Reply-To: <577E89E5.3070100@arm.com>


On 2016/7/8 0:57, Julien Grall wrote:
> On 07/07/16 17:15, Wei Liu wrote:
>> On Tue, Jul 05, 2016 at 11:12:47AM +0800, Shannon Zhao wrote:
>>> From: Shannon Zhao <shannon.zhao@linaro.org>
>>>
>>> The guest kernel will get the event channel interrupt information via
>>> domain param HVM_PARAM_CALLBACK_IRQ. Initialize it here.
>>>
>>> Signed-off-by: Shannon Zhao <shannon.zhao@linaro.org>
>>> ---
>>>   tools/libxl/libxl_arm.c | 11 +++++++++++
>>>   1 file changed, 11 insertions(+)
>>>
>>> diff --git a/tools/libxl/libxl_arm.c b/tools/libxl/libxl_arm.c
>>> index bc38318..acacba0 100644
>>> --- a/tools/libxl/libxl_arm.c
>>> +++ b/tools/libxl/libxl_arm.c
>>> @@ -900,8 +900,19 @@ int
>>> libxl__arch_domain_init_hw_description(libxl__gc *gc,
>>>                                              struct xc_dom_image *dom)
>>>   {
>>>       int rc;
>>> +    uint64_t val;
>>>
>>>       assert(info->type == LIBXL_DOMAIN_TYPE_PV);
>>> +
>>> +    /* Set the value of domain param HVM_PARAM_CALLBACK_IRQ. */
>>> +    val = (uint64_t)HVM_PARAM_CALLBACK_TYPE_PPI << 56;
>>> +    val |= (2 << 8); /* Active-low level-sensitive  */
>>
>> Please avoid using magic numbers here -- 56, 2 and 8.
> 
> The magic numbers are described in public/hvm/params.h however there is
> no defines associated to them.
> 
> The public header would need to be updated if we don't want the value
> hardcoded in libxl.
> 
ok, so do we decide to update that?

>>
>> Another question to Julien and Stefano: is it normal for ARM guest to
>> use hvm callback vector?
> 
> Yes. The HVM callback vector is used by ACPI guest to find the PPI
> (per-cpu interrupt) which will be used to notify event.
> 
> This is how DOM0 is using ACPI on ARM (see [1]), I don't think we should
> differ here.
> 
> BTW, I have noticed that the design doc is only available on the ML.
> Shannon, would it be possible to send a patch to add it in docs/misc/arm?
> 
Ok, I'll send a patch later.

> [2] https://lists.xen.org/archives/html/xen-devel/2015-11/msg00488.html

-- 
Shannon


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