linux-kernel - Re: [Xen-devel] [PATCH v2 08/16] xen/hvm/params: Add a new delivery type for event-channel in HVM_PARAM_CALLBACK

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Date:	Mon, 18 Jan 2016 12:42:31 +0000
From:	Andrew Cooper <andrew.cooper3@...rix.com>
To:	Stefano Stabellini <stefano.stabellini@...citrix.com>
CC:	<linux-arm-kernel@...ts.infradead.org>,
	<ard.biesheuvel@...aro.org>, <stefano.stabellini@...rix.com>,
	<david.vrabel@...rix.com>, <mark.rutland@....com>,
	<devicetree@...r.kernel.org>, <linux-efi@...r.kernel.org>,
	<catalin.marinas@....com>, <will.deacon@....com>,
	<linux-kernel@...r.kernel.org>, <xen-devel@...ts.xen.org>,
	<julien.grall@...rix.com>, <shannon.zhao@...aro.org>,
	<peter.huangpeng@...wei.com>, <zhaoshenglong@...wei.com>
Subject: Re: [Xen-devel] [PATCH v2 08/16] xen/hvm/params: Add a new delivery
 type for event-channel in HVM_PARAM_CALLBACK_IRQ

On 18/01/16 12:38, Stefano Stabellini wrote:
> On Fri, 15 Jan 2016, Shannon Zhao wrote:
>> From: Shannon Zhao <shannon.zhao@...aro.org>
>>
>> Add a new delivery type:
>> val[63:56] == 3: val[15:8] is flag: val[7:0] is a PPI.
>> To the flag, bit 0 stands the interrupt mode is edge(1) or level(0) and
>> bit 1 stands the interrupt polarity is active low(1) or high(0).
>>
>> Signed-off-by: Shannon Zhao <shannon.zhao@...aro.org>
>> ---
>>  include/xen/interface/hvm/params.h | 5 +++++
>>  1 file changed, 5 insertions(+)
>>
>> diff --git a/include/xen/interface/hvm/params.h b/include/xen/interface/hvm/params.h
>> index a6c7991..550688a 100644
>> --- a/include/xen/interface/hvm/params.h
>> +++ b/include/xen/interface/hvm/params.h
>> @@ -34,6 +34,11 @@
>>   *                  Domain = val[47:32], Bus  = val[31:16],
>>   *                  DevFn  = val[15: 8], IntX = val[ 1: 0]
>>   * val[63:56] == 2: val[7:0] is a vector number.
>> + * val[63:56] == 3: val[15:8] is flag of event-channel interrupt:
>> + *                      bit 0: interrupt is edge(1) or level(0) triggered
>> + *                      bit 1: interrupt is active low(1) or high(0)
>> + *                  val[7:0] is PPI number used by event-channel.
>> + *                  This is only used by ARM/ARM64.
>>   * If val == 0 then CPU0 event-channel notifications are not delivered.
>>   */
>>  #define HVM_PARAM_CALLBACK_IRQ 0
> Andrew, I think that this patch is correct. Looking back at your
> previous comment (http://marc.info/?l=devicetree&m=144804014214262&w=2),
> is it possible that you were confused by enum callback_via_type, which
> is internal to Xen and offset'ed by 1 compared to the described values
> in xen/include/public/hvm/params.h?
>
> If not, and indeed somebody introduced one more field but failed to
> document it, then I suggest she sends a patch to fix the issue as soon
> as possible.

I was indeed confused - the ABI is utterly mad.

However, this change does need rebasing over c/s ca5c54b, which was the
result of the original discussion.

~Andrew