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From: Auger Eric <eric.auger-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
To: Thomas Gleixner <tglx-hfZtesqFncYOwBW4kG4KsQ@public.gmane.org>
Cc: yehuday-eYqpPyKDWXRBDgjK7y7TUQ@public.gmane.org,
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	kvm-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
	marc.zyngier-5wv7dgnIgG8@public.gmane.org,
	p.fedin-Sze3O3UU22JBDgjK7y7TUQ@public.gmane.org,
	will.deacon-5wv7dgnIgG8@public.gmane.org,
	linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
	iommu-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org,
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	robert.richter-M3mlKVOIwJVv6pq1l3V1OdBPR1lH4CV8@public.gmane.org,
	dennis.chen-5wv7dgnIgG8@public.gmane.org,
	Manish.Jaggi-M3mlKVOIwJVv6pq1l3V1OdBPR1lH4CV8@public.gmane.org,
	christoffer.dall-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org,
	eric.auger.pro-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org
Subject: Re: [PATCH v12 02/11] genirq/msi: msi_compose wrapper
Date: Wed, 10 Aug 2016 10:48:02 +0200	[thread overview]
Message-ID: <bc3270b2-340b-9396-0722-2c2097f7fae4@redhat.com> (raw)
In-Reply-To: <alpine.DEB.2.20.1608091117250.5388@nanos>

Hi Thomas,

On 09/08/2016 11:19, Thomas Gleixner wrote:
> On Tue, 2 Aug 2016, Eric Auger wrote:
> 
>> Currently the MSI message is composed by directly calling
>> irq_chip_compose_msi_msg and erased by setting the memory to zero.
>>
>> On some platforms, we will need to complexify this composition to
>> properly handle MSI emission through IOMMU. Also we will need to track
>> when the MSI message is erased.
> 
> I just can't find how you do that. After applying the series the
> 
>> +	if (erase)
>> +		memset(msg, 0, sizeof(*msg));
> 
> branch is still just a memset(). The wrapper is fine for the compose side, but
> having the extra argument just to wrap the memset() for no gain is silly.

Yes you're right: this was true in the first releases of the series
where the iommu mapping/unmapping were done at composition & erase time.
Now the mapping/unmapping is done on msi_domain_alloc/free_irqs, this is
not mandated anymore. I will keep the wrapper for the compose side and
remove the rest + update the commit message accordingly.

Thank you for your time.

Eric
> 
> Thanks,
> 
> 	tglx
> --
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  reply	other threads:[~2016-08-10  8:48 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-08-02 17:23 [PATCH v12 00/11] KVM PCIe/MSI passthrough on ARM/ARM64: kernel part 2/3: msi changes Eric Auger
     [not found] ` <1470158617-7022-1-git-send-email-eric.auger-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2016-08-02 17:23   ` [PATCH v12 01/11] genirq/msi: export msi_get_domain_info Eric Auger
2016-08-02 17:23   ` [PATCH v12 02/11] genirq/msi: msi_compose wrapper Eric Auger
2016-08-09  9:19     ` Thomas Gleixner
2016-08-10  8:48       ` Auger Eric [this message]
2016-08-02 17:23   ` [PATCH v12 03/11] genirq: Introduce irq_get_msi_doorbell_info Eric Auger
2016-08-02 17:23   ` [PATCH v12 04/11] genirq/msi: Allow MSI doorbell (un)registration Eric Auger
2016-08-02 17:23   ` [PATCH v12 05/11] genirq/msi: msi_doorbell_calc_pages Eric Auger
2016-08-02 17:23   ` [PATCH v12 06/11] genirq/msi: msi_doorbell_safe Eric Auger
2016-08-02 17:23   ` [PATCH v12 07/11] irqchip/gic-v2m: Register the MSI global doorbell Eric Auger
2016-08-02 17:23   ` [PATCH v12 08/11] irqchip/gicv3-its: " Eric Auger
2016-08-02 17:23   ` [PATCH v12 09/11] genirq/msi: Introduce msi_desc flags Eric Auger
     [not found]     ` <1470158617-7022-10-git-send-email-eric.auger-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2016-08-09  6:52       ` Auger Eric
2016-08-02 17:23   ` [PATCH v12 10/11] genirq/msi: Map/unmap the MSI doorbells on msi_domain_alloc/free_irqs Eric Auger
2016-08-02 17:23   ` [PATCH v12 11/11] genirq/msi: Use the MSI doorbell's IOVA when requested Eric Auger

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