From mboxrd@z Thu Jan 1 00:00:00 1970 From: Alexey Kardashevskiy Date: Tue, 28 May 2013 23:30:40 +0000 Subject: Re: [PATCH 3/4] KVM: PPC: Add support for IOMMU in-kernel handling Message-Id: <51A53E20.3020205@ozlabs.ru> List-Id: References: <1369763138.18630.3@snotra> In-Reply-To: <1369763138.18630.3@snotra> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Scott Wood 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 05/29/2013 03:45 AM, Scott Wood wrote: > 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. Yes, would be nice. There is just no quick way to know if this real system supports IOMMU groups. I could add another helper to generic IOMMU code which would return the number of registered IOMMU groups but it is a bit too much :) >> >>> @@ -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? Yes. -- Alexey From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pd0-f182.google.com (mail-pd0-f182.google.com [209.85.192.182]) (using TLSv1 with cipher ECDHE-RSA-RC4-SHA (128/128 bits)) (Client CN "smtp.gmail.com", Issuer "Google Internet Authority" (not verified)) by ozlabs.org (Postfix) with ESMTPS id 0E0EE2C0336 for ; Wed, 29 May 2013 09:30:49 +1000 (EST) Received: by mail-pd0-f182.google.com with SMTP id g10so8205278pdj.13 for ; Tue, 28 May 2013 16:30:47 -0700 (PDT) Message-ID: <51A53E20.3020205@ozlabs.ru> Date: Wed, 29 May 2013 09:30:40 +1000 From: Alexey Kardashevskiy MIME-Version: 1.0 To: Scott Wood Subject: Re: [PATCH 3/4] KVM: PPC: Add support for IOMMU in-kernel handling References: <1369763138.18630.3@snotra> In-Reply-To: <1369763138.18630.3@snotra> Content-Type: text/plain; charset=KOI8-R 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 05/29/2013 03:45 AM, Scott Wood wrote: > 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. Yes, would be nice. There is just no quick way to know if this real system supports IOMMU groups. I could add another helper to generic IOMMU code which would return the number of registered IOMMU groups but it is a bit too much :) >> >>> @@ -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? Yes. -- Alexey From mboxrd@z Thu Jan 1 00:00:00 1970 From: Alexey Kardashevskiy Subject: Re: [PATCH 3/4] KVM: PPC: Add support for IOMMU in-kernel handling Date: Wed, 29 May 2013 09:30:40 +1000 Message-ID: <51A53E20.3020205@ozlabs.ru> References: <1369763138.18630.3@snotra> Mime-Version: 1.0 Content-Type: text/plain; charset=KOI8-R Content-Transfer-Encoding: 7bit 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 To: Scott Wood Return-path: In-Reply-To: <1369763138.18630.3@snotra> Sender: linux-kernel-owner@vger.kernel.org List-Id: kvm.vger.kernel.org On 05/29/2013 03:45 AM, Scott Wood wrote: > 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. Yes, would be nice. There is just no quick way to know if this real system supports IOMMU groups. I could add another helper to generic IOMMU code which would return the number of registered IOMMU groups but it is a bit too much :) >> >>> @@ -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? Yes. -- Alexey