From mboxrd@z Thu Jan  1 00:00:00 1970
From: pbonzini@redhat.com (Paolo Bonzini)
Date: Mon, 6 Jul 2015 13:51:24 +0200
Subject: [PATCH 1/7] KVM: api: add kvm_irq_routing_extended_msi
In-Reply-To: <559A6527.1040107@arm.com>
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 <00fd01d0b7b6$f6cf3550$e46d9ff0$@samsung.com> <559A3C9C.6050302@arm.com>
 <20150706093026.GA11590@cbox> <559A52E6.5050402@arm.com>
 <20150706103755.GC11590@cbox> <559A6164.1000401@redhat.com>
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Message-ID: <559A6BBC.2040901@redhat.com>
To: linux-arm-kernel@lists.infradead.org
List-Id: linux-arm-kernel.lists.infradead.org



On 06/07/2015 13:23, Andre Przywara wrote:
> Hi Paolo,
> 
> thanks for looking at this!
> 
> On 06/07/15 12:07, Paolo Bonzini wrote:
>>
>>
>> On 06/07/2015 12:37, Christoffer Dall wrote:
>>> I don't view it as 'the kernel requires this' but as 'the kernel will
>>> not complain with arbitrary error code if you set the devid flag'
>>> capability, and it's up to userspace (as usual) to provide the correct
>>> arguments for things to work, and up to the kernel to ensure we don't
>>> crash the system etc.
>>>
>>> Thus, if you want to advertise it as a capability, I would rather call
>>> it KVM_CAP_MSI_DEVID.
>>
>> I agree.  Does userspace know that ITS guests always require devid?
> 
> Well, as we are about to implement this: yes. But the issue is that MSI
> injection and GSI routing code is generic PCI code in userland (at least
> in kvmtool, guess in QEMU, too), so I don't want to pull in any kind of
> ARM specific code in there. The idea is to always provide the device ID
> from the PCI code (for PCI devices it's just the B/D/F triplet), but
> only send it to the kernel if needed. Querying a KVM capability is
> perfectly fine for this IMO.

Yes, I agree.

Paolo