Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932827Ab3E0OmN (ORCPT ); Mon, 27 May 2013 10:42:13 -0400 Received: from mx1.redhat.com ([209.132.183.28]:18948 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932737Ab3E0OmL (ORCPT ); Mon, 27 May 2013 10:42:11 -0400 Message-ID: <51A370AF.4090208@redhat.com> Date: Mon, 27 May 2013 16:41:51 +0200 From: Paolo Bonzini User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130514 Thunderbird/17.0.6 MIME-Version: 1.0 To: Alexey Kardashevskiy CC: David Gibson , Scott Wood , kvm@vger.kernel.org, linux-kernel@vger.kernel.org, kvm-ppc@vger.kernel.org, Alexander Graf , Paul Mackerras , linuxppc-dev@lists.ozlabs.org Subject: Re: [PATCH 3/4] KVM: PPC: Add support for IOMMU in-kernel handling References: <1369105607-20957-4-git-send-email-aik@ozlabs.ru> <1369256817.1374.29@scott-Lenovo-G560> <20130525024524.GA6112@boomeroo.fritz.box> <51A33418.40909@redhat.com> <51A36D28.7090202@ozlabs.ru> In-Reply-To: <51A36D28.7090202@ozlabs.ru> X-Enigmail-Version: 1.5.1 Content-Type: text/plain; charset=KOI8-R Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1946 Lines: 49 Il 27/05/2013 16:26, Alexey Kardashevskiy ha scritto: > On 05/27/2013 08:23 PM, Paolo Bonzini wrote: >> Il 25/05/2013 04:45, David Gibson ha scritto: >>>>> + case KVM_CREATE_SPAPR_TCE_IOMMU: { >>>>> + struct kvm_create_spapr_tce_iommu create_tce_iommu; >>>>> + struct kvm *kvm = filp->private_data; >>>>> + >>>>> + r = -EFAULT; >>>>> + if (copy_from_user(&create_tce_iommu, argp, >>>>> + sizeof(create_tce_iommu))) >>>>> + goto out; >>>>> + r = kvm_vm_ioctl_create_spapr_tce_iommu(kvm, >>>>> &create_tce_iommu); >>>>> + goto out; >>>>> + } >> >> Would it make sense to make this the only interface for creating TCEs? >> That is, pass both a window_size and an IOMMU group id (or e.g. -1 for >> no hardware IOMMU usage), and have a single ioctl for both cases? >> There's some duplicated code between kvm_vm_ioctl_create_spapr_tce and >> kvm_vm_ioctl_create_spapr_tce_iommu. > > Just few bits. Is there really much sense in making one function from those > two? I tried, looked a bit messy. Cannot really tell without the userspace bits. But ioctl proliferation is what the device and one_reg APIs were supposed to avoid... >> KVM_CREATE_SPAPR_TCE could stay for backwards-compatibility, or you >> could just use a new capability and drop the old ioctl. > > The old capability+ioctl already exist for quite a while and few QEMU > versions supporting it were released so we do not want just drop it. So > then what is the benefit of having a new interface with support of both types? > >> I'm not sure >> whether you're already considering the ABI to be stable for kvmppc. > > Is any bit of KVM using it? Cannot see from Documentation/ABI. I mean the userspace ABI (ioctls). Paolo -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/