From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: Gleb Natapov <gleb@redhat.com>
Cc: Alexey Kardashevskiy <aik@ozlabs.ru>,
linuxppc-dev@lists.ozlabs.org,
David Gibson <david@gibson.dropbear.id.au>,
Paul Mackerras <paulus@samba.org>,
Paolo Bonzini <pbonzini@redhat.com>,
Alexander Graf <agraf@suse.de>,
kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
kvm-ppc@vger.kernel.org, linux-mm@kvack.org
Subject: Re: [PATCH v9 12/13] KVM: PPC: Add support for IOMMU in-kernel handling
Date: Thu, 05 Sep 2013 14:05:09 +1000 [thread overview]
Message-ID: <1378353909.4321.126.camel@pasglop> (raw)
In-Reply-To: <20130903105315.GY22899@redhat.com>
On Tue, 2013-09-03 at 13:53 +0300, Gleb Natapov wrote:
> > Or supporting all IOMMU links (and leaving emulated stuff as is) in on
> > "device" is the last thing I have to do and then you'll ack the patch?
> >
> I am concerned more about API here. Internal implementation details I
> leave to powerpc experts :)
So Gleb, I want to step in for a bit here.
While I understand that the new KVM device API is all nice and shiny and that this
whole thing should probably have been KVM devices in the first place (had they
existed or had we been told back then), the point is, the API for handling
HW IOMMUs that Alexey is trying to add is an extension of an existing mechanism
used for emulated IOMMUs.
The internal data structure is shared, and fundamentally, by forcing him to
use that new KVM device for the "new stuff", we create a oddball API with
an ioctl for one type of iommu and a KVM device for the other, which makes
the implementation a complete mess in the kernel (and you should care :-)
So for something completely new, I would tend to agree with you. However, I
still think that for this specific case, we should just plonk-in the original
ioctl proposed by Alexey and be done with it.
Cheers,
Ben.
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next prev parent reply other threads:[~2013-09-05 4:05 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-08-28 8:37 [PATCH v9 00/13] KVM: PPC: IOMMU in-kernel handling of VFIO Alexey Kardashevskiy
2013-08-28 8:37 ` [PATCH v9 01/13] KVM: PPC: POWERNV: move iommu_add_device earlier Alexey Kardashevskiy
2013-10-30 5:33 ` Bhushan Bharat-R65777
2013-08-28 8:37 ` [PATCH v9 02/13] hashtable: add hash_for_each_possible_rcu_notrace() Alexey Kardashevskiy
2013-08-28 8:37 ` [PATCH v9 03/13] KVM: PPC: reserve a capability number for multitce support Alexey Kardashevskiy
2013-08-28 8:37 ` [PATCH v9 04/13] KVM: PPC: reserve a capability and KVM device type for realmode VFIO Alexey Kardashevskiy
2013-09-01 11:27 ` Gleb Natapov
2013-09-01 11:39 ` Alexey Kardashevskiy
2013-09-01 12:04 ` Gleb Natapov
2013-08-28 8:37 ` [PATCH v9 05/13] powerpc: Prepare to support kernel handling of IOMMU map/unmap Alexey Kardashevskiy
2013-08-28 8:37 ` [PATCH v9 06/13] powerpc: add real mode support for dma operations on powernv Alexey Kardashevskiy
2013-08-28 8:37 ` [PATCH v9 07/13] KVM: PPC: enable IOMMU_API for KVM_BOOK3S_64 permanently Alexey Kardashevskiy
2013-08-28 8:37 ` [PATCH v9 08/13] KVM: PPC: Add support for multiple-TCE hcalls Alexey Kardashevskiy
2013-08-28 8:37 ` [PATCH v9 09/13] powerpc/iommu: rework to support realmode Alexey Kardashevskiy
2013-08-28 8:49 ` [PATCH v9 10/13] KVM: PPC: remove warning from kvmppc_core_destroy_vm Alexey Kardashevskiy
2013-08-28 8:50 ` [PATCH v9 11/13] KVM: PPC: add trampolines for VFIO external API Alexey Kardashevskiy
2013-08-28 8:50 ` [PATCH v9 12/13] KVM: PPC: Add support for IOMMU in-kernel handling Alexey Kardashevskiy
2013-09-01 12:06 ` Gleb Natapov
2013-09-02 3:14 ` Alexey Kardashevskiy
2013-09-03 10:53 ` Gleb Natapov
2013-09-03 16:01 ` Alexey Kardashevskiy
2013-09-05 18:10 ` Gleb Natapov
2013-09-05 23:38 ` Alexey Kardashevskiy
2013-09-06 6:01 ` Gleb Natapov
2013-09-06 6:06 ` Alexey Kardashevskiy
2013-09-05 4:05 ` Benjamin Herrenschmidt [this message]
2013-09-06 6:57 ` Gleb Natapov
2013-09-06 7:04 ` Alexey Kardashevskiy
2013-09-06 10:45 ` Alexey Kardashevskiy
2013-08-28 8:51 ` [PATCH v9 13/13] KVM: PPC: Add hugepage " Alexey Kardashevskiy
2013-08-30 10:26 ` [PATCH v9 00/13] KVM: PPC: IOMMU in-kernel handling of VFIO Alexey Kardashevskiy
2013-08-30 17:58 ` Gleb Natapov
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