From mboxrd@z Thu Jan 1 00:00:00 1970 From: Scott Wood Date: Tue, 28 May 2013 17:45:38 +0000 Subject: Re: [PATCH 3/4] KVM: PPC: Add support for IOMMU in-kernel handling Message-Id: <1369763138.18630.3@snotra> List-Id: In-Reply-To: <51A2C888.4050704@ozlabs.ru> (from aik@ozlabs.ru on Sun May 26 21:44:24 2013) References: <1369105607-20957-4-git-send-email-aik@ozlabs.ru> In-Reply-To: <1369105607-20957-4-git-send-email-aik@ozlabs.ru> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Alexey Kardashevskiy Cc: David Gibson , kvm@vger.kernel.org, linux-kernel@vger.kernel.org, kvm-ppc@vger.kernel.org, Alexander Graf , Paul Mackerras , linuxppc-dev@lists.ozlabs.org On 05/26/2013 09:44:24 PM, Alexey Kardashevskiy wrote: > On 05/25/2013 12:45 PM, David Gibson wrote: > > On Wed, May 22, 2013 at 04:06:57PM -0500, Scott Wood wrote: > >> On 05/20/2013 10:06:46 PM, Alexey Kardashevskiy wrote: > >>> diff --git a/arch/powerpc/kvm/powerpc.c > b/arch/powerpc/kvm/powerpc.c > >>> index 8465c2a..da6bf61 100644 > >>> --- a/arch/powerpc/kvm/powerpc.c > >>> @@ -396,6 +396,7 @@ int kvm_dev_ioctl_check_extension(long ext) > >>> +++ b/arch/powerpc/kvm/powerpc.c > >>> break; > >>> #endif > >>> case KVM_CAP_SPAPR_MULTITCE: > >>> + case KVM_CAP_SPAPR_TCE_IOMMU: > >>> r = 1; > >>> break; > >>> default: > >> > >> Don't advertise SPAPR capabilities if it's not book3s -- and > >> probably there's some additional limitation that would be > >> appropriate. > > > > So, in the case of MULTITCE, that's not quite right. PR KVM can > > emulate a PAPR system on a BookE machine, and there's no reason not > to > > allow TCE acceleration as well. We can't make it dependent on PAPR > > mode being selected, because that's enabled per-vcpu, whereas these > > capabilities are queried on the VM before the vcpus are created. > > > > CAP_SPAPR_TCE_IOMMU should be dependent on the presence of suitable > > host side hardware (i.e. a PAPR style IOMMU), though. > > > The capability says that the ioctl is supported. If there is no IOMMU > group > registered, than it will fail with a reasonable error and nobody gets > hurt. > What is the problem? You could say that about a lot of the capabilities that just advertise the existence of new ioctls. :-) Sometimes it's nice to know in advance whether it's supported, before actually requesting that something happen. > >>> @@ -939,6 +940,9 @@ struct kvm_s390_ucas_mapping { > >>> #define KVM_GET_DEVICE_ATTR _IOW(KVMIO, 0xe2, struct > >>> kvm_device_attr) > >>> #define KVM_HAS_DEVICE_ATTR _IOW(KVMIO, 0xe3, struct > >>> kvm_device_attr) > >>> > >>> +/* ioctl for SPAPR TCE IOMMU */ > >>> +#define KVM_CREATE_SPAPR_TCE_IOMMU _IOW(KVMIO, 0xe4, struct > >>> kvm_create_spapr_tce_iommu) > >> > >> Shouldn't this go under the vm ioctl section? > > > The KVM_CREATE_SPAPR_TCE_IOMMU ioctl (the version for emulated > devices) is > in this section so I decided to keep them together. Wrong? You decided to keep KVM_CREATE_SPAPR_TCE_IOMMU together with KVM_CREATE_SPAPR_TCE_IOMMU? -Scott From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from db8outboundpool.messaging.microsoft.com (mail-db8lp0186.outbound.messaging.microsoft.com [213.199.154.186]) (using TLSv1 with cipher AES128-SHA (128/128 bits)) (Client CN "mail.global.frontbridge.com", Issuer "MSIT Machine Auth CA 2" (not verified)) by ozlabs.org (Postfix) with ESMTPS id 862902C032C for ; Wed, 29 May 2013 03:46:08 +1000 (EST) Date: Tue, 28 May 2013 12:45:38 -0500 From: Scott Wood Subject: Re: [PATCH 3/4] KVM: PPC: Add support for IOMMU in-kernel handling To: Alexey Kardashevskiy In-Reply-To: <51A2C888.4050704@ozlabs.ru> (from aik@ozlabs.ru on Sun May 26 21:44:24 2013) Message-ID: <1369763138.18630.3@snotra> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; delsp=Yes; format=Flowed Cc: kvm@vger.kernel.org, Alexander Graf , kvm-ppc@vger.kernel.org, linux-kernel@vger.kernel.org, Paul Mackerras , linuxppc-dev@lists.ozlabs.org, David Gibson List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On 05/26/2013 09:44:24 PM, Alexey Kardashevskiy wrote: > On 05/25/2013 12:45 PM, David Gibson wrote: > > On Wed, May 22, 2013 at 04:06:57PM -0500, Scott Wood wrote: > >> On 05/20/2013 10:06:46 PM, Alexey Kardashevskiy wrote: > >>> diff --git a/arch/powerpc/kvm/powerpc.c =20 > b/arch/powerpc/kvm/powerpc.c > >>> index 8465c2a..da6bf61 100644 > >>> --- a/arch/powerpc/kvm/powerpc.c > >>> @@ -396,6 +396,7 @@ int kvm_dev_ioctl_check_extension(long ext) > >>> +++ b/arch/powerpc/kvm/powerpc.c > >>> break; > >>> #endif > >>> case KVM_CAP_SPAPR_MULTITCE: > >>> + case KVM_CAP_SPAPR_TCE_IOMMU: > >>> r =3D 1; > >>> break; > >>> default: > >> > >> Don't advertise SPAPR capabilities if it's not book3s -- and > >> probably there's some additional limitation that would be > >> appropriate. > > > > So, in the case of MULTITCE, that's not quite right. PR KVM can > > emulate a PAPR system on a BookE machine, and there's no reason not =20 > to > > allow TCE acceleration as well. We can't make it dependent on PAPR > > mode being selected, because that's enabled per-vcpu, whereas these > > capabilities are queried on the VM before the vcpus are created. > > > > CAP_SPAPR_TCE_IOMMU should be dependent on the presence of suitable > > host side hardware (i.e. a PAPR style IOMMU), though. >=20 >=20 > The capability says that the ioctl is supported. If there is no IOMMU =20 > group > registered, than it will fail with a reasonable error and nobody gets =20 > hurt. > What is the problem? You could say that about a lot of the capabilities that just advertise =20 the existence of new ioctls. :-) Sometimes it's nice to know in advance whether it's supported, before =20 actually requesting that something happen. > >>> @@ -939,6 +940,9 @@ struct kvm_s390_ucas_mapping { > >>> #define KVM_GET_DEVICE_ATTR _IOW(KVMIO, 0xe2, struct > >>> kvm_device_attr) > >>> #define KVM_HAS_DEVICE_ATTR _IOW(KVMIO, 0xe3, struct > >>> kvm_device_attr) > >>> > >>> +/* ioctl for SPAPR TCE IOMMU */ > >>> +#define KVM_CREATE_SPAPR_TCE_IOMMU _IOW(KVMIO, 0xe4, struct > >>> kvm_create_spapr_tce_iommu) > >> > >> Shouldn't this go under the vm ioctl section? >=20 >=20 > The KVM_CREATE_SPAPR_TCE_IOMMU ioctl (the version for emulated =20 > devices) is > in this section so I decided to keep them together. Wrong? You decided to keep KVM_CREATE_SPAPR_TCE_IOMMU together with =20 KVM_CREATE_SPAPR_TCE_IOMMU? -Scott= From mboxrd@z Thu Jan 1 00:00:00 1970 From: Scott Wood Subject: Re: [PATCH 3/4] KVM: PPC: Add support for IOMMU in-kernel handling Date: Tue, 28 May 2013 12:45:38 -0500 Message-ID: <1369763138.18630.3@snotra> References: <51A2C888.4050704@ozlabs.ru> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; delsp=Yes; format=Flowed Content-Transfer-Encoding: 8BIT Cc: David Gibson , , , , Alexander Graf , Paul Mackerras , To: Alexey Kardashevskiy Return-path: In-Reply-To: <51A2C888.4050704@ozlabs.ru> (from aik@ozlabs.ru on Sun May 26 21:44:24 2013) Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org List-Id: kvm.vger.kernel.org On 05/26/2013 09:44:24 PM, Alexey Kardashevskiy wrote: > On 05/25/2013 12:45 PM, David Gibson wrote: > > On Wed, May 22, 2013 at 04:06:57PM -0500, Scott Wood wrote: > >> On 05/20/2013 10:06:46 PM, Alexey Kardashevskiy wrote: > >>> diff --git a/arch/powerpc/kvm/powerpc.c > b/arch/powerpc/kvm/powerpc.c > >>> index 8465c2a..da6bf61 100644 > >>> --- a/arch/powerpc/kvm/powerpc.c > >>> @@ -396,6 +396,7 @@ int kvm_dev_ioctl_check_extension(long ext) > >>> +++ b/arch/powerpc/kvm/powerpc.c > >>> break; > >>> #endif > >>> case KVM_CAP_SPAPR_MULTITCE: > >>> + case KVM_CAP_SPAPR_TCE_IOMMU: > >>> r = 1; > >>> break; > >>> default: > >> > >> Don't advertise SPAPR capabilities if it's not book3s -- and > >> probably there's some additional limitation that would be > >> appropriate. > > > > So, in the case of MULTITCE, that's not quite right. PR KVM can > > emulate a PAPR system on a BookE machine, and there's no reason not > to > > allow TCE acceleration as well. We can't make it dependent on PAPR > > mode being selected, because that's enabled per-vcpu, whereas these > > capabilities are queried on the VM before the vcpus are created. > > > > CAP_SPAPR_TCE_IOMMU should be dependent on the presence of suitable > > host side hardware (i.e. a PAPR style IOMMU), though. > > > The capability says that the ioctl is supported. If there is no IOMMU > group > registered, than it will fail with a reasonable error and nobody gets > hurt. > What is the problem? You could say that about a lot of the capabilities that just advertise the existence of new ioctls. :-) Sometimes it's nice to know in advance whether it's supported, before actually requesting that something happen. > >>> @@ -939,6 +940,9 @@ struct kvm_s390_ucas_mapping { > >>> #define KVM_GET_DEVICE_ATTR _IOW(KVMIO, 0xe2, struct > >>> kvm_device_attr) > >>> #define KVM_HAS_DEVICE_ATTR _IOW(KVMIO, 0xe3, struct > >>> kvm_device_attr) > >>> > >>> +/* ioctl for SPAPR TCE IOMMU */ > >>> +#define KVM_CREATE_SPAPR_TCE_IOMMU _IOW(KVMIO, 0xe4, struct > >>> kvm_create_spapr_tce_iommu) > >> > >> Shouldn't this go under the vm ioctl section? > > > The KVM_CREATE_SPAPR_TCE_IOMMU ioctl (the version for emulated > devices) is > in this section so I decided to keep them together. Wrong? You decided to keep KVM_CREATE_SPAPR_TCE_IOMMU together with KVM_CREATE_SPAPR_TCE_IOMMU? -Scott