From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 1EE45C282C2 for ; Wed, 13 Feb 2019 11:55:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D7EF1222B2 for ; Wed, 13 Feb 2019 11:55:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2392034AbfBMLzw (ORCPT ); Wed, 13 Feb 2019 06:55:52 -0500 Received: from foss.arm.com ([217.140.101.70]:52552 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1733126AbfBMLzw (ORCPT ); Wed, 13 Feb 2019 06:55:52 -0500 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.72.51.249]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 51A9CA78; Wed, 13 Feb 2019 03:55:51 -0800 (PST) Received: from [10.1.197.2] (ostrya.cambridge.arm.com [10.1.197.2]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 419D43F557; Wed, 13 Feb 2019 03:55:48 -0800 (PST) Subject: Re: [PATCH v6 1/9] iommu: Add APIs for multiple domains per device To: Lu Baolu , Joerg Roedel , David Woodhouse , Alex Williamson , Kirti Wankhede Cc: "ashok.raj@intel.com" , "sanjay.k.kumar@intel.com" , "jacob.jun.pan@intel.com" , "kevin.tian@intel.com" , "yi.l.liu@intel.com" , "yi.y.sun@intel.com" , "peterx@redhat.com" , "tiwei.bie@intel.com" , "xin.zeng@intel.com" , "iommu@lists.linux-foundation.org" , "kvm@vger.kernel.org" , "linux-kernel@vger.kernel.org" , Jacob Pan References: <20190213040301.23021-1-baolu.lu@linux.intel.com> <20190213040301.23021-2-baolu.lu@linux.intel.com> From: Jean-Philippe Brucker Message-ID: <1735d302-8fab-68b5-d016-01731546fd36@arm.com> Date: Wed, 13 Feb 2019 11:55:31 +0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.4.0 MIME-Version: 1.0 In-Reply-To: <20190213040301.23021-2-baolu.lu@linux.intel.com> Content-Type: text/plain; charset=windows-1252 Content-Language: en-US Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi, I have a few boring nits and one question below On 13/02/2019 04:02, Lu Baolu wrote: > Sharing a physical PCI device in a finer-granularity way > is becoming a consensus in the industry. IOMMU vendors > are also engaging efforts to support such sharing as well > as possible. Among the efforts, the capability of support > finer-granularity DMA isolation is a common requirement > due to the security consideration. With finer-granularity > DMA isolation, all DMA requests out of or to a subset of > a physical PCI device can be protected by the IOMMU. That last sentence seems strange, how about "With finer-granularity DMA isolation, subsets of a PCI function can be isolated from each others by the IOMMU." > As a > result, there is a request in software to attach multiple > domains to a physical PCI device. One example of such use > model is the Intel Scalable IOV [1] [2]. The Intel vt-d > 3.0 spec [3] introduces the scalable mode which enables > PASID granularity DMA isolation. > > This adds the APIs to support multiple domains per device. > In order to ease the discussions, we call it 'a domain in > auxiliary mode' or simply 'auxiliary domain' when multiple > domains are attached to a physical device. > > The APIs include: > > * iommu_dev_has_feature(dev, IOMMU_DEV_FEAT_AUX) >   - Check whether both IOMMU and device support IOMMU aux >     domain feature. Below aux-domain specific interfaces >     are available only after this returns true. s/after/if/ since calling has_feature() shouldn't be a prerequisite to using the aux-domain interface (unlike calling enable_feature()). > > * iommu_dev_enable/disable_feature(dev, IOMMU_DEV_FEAT_AUX) >   - Enable/disable device specific aux-domain feature. > > * iommu_dev_feature_enabled(dev, IOMMU_DEV_FEAT_AUX) >   - Check whether the aux domain specific feature enabled or >     not. "is enabled" > > * iommu_aux_attach_device(domain, dev) >   - Attaches @domain to @dev in the auxiliary mode. Multiple >     domains could be attached to a single device in the >     auxiliary mode with each domain representing an isolated >     address space for an assignable subset of the device. > > * iommu_aux_detach_device(domain, dev) >   - Detach @domain which has been attached to @dev in the >     auxiliary mode. > > * iommu_aux_get_pasid(domain, dev) >   - Return ID used for finer-granularity DMA translation. >     For the Intel Scalable IOV usage model, this will be >     a PASID. The device which supports Scalable IOV needs >     to write this ID to the device register so that DMA >     requests could be tagged with a right PASID prefix. > > This has been updated with the latest proposal from Joerg > posted here [5]. > > Many people involved in discussions of this design. > > Kevin Tian > Liu Yi L > Ashok Raj > Sanjay Kumar > Jacob Pan > Alex Williamson > Jean-Philippe Brucker > Joerg Roedel > > and some discussions can be found here [4] [5]. > > [1] > https://software.intel.com/en-us/download/intel-scalable-io-virtualization-technical-specification > [2] https://schd.ws/hosted_files/lc32018/00/LC3-SIOV-final.pdf > [3] > https://software.intel.com/en-us/download/intel-virtualization-technology-for-directed-io-architecture-specification > [4] https://lkml.org/lkml/2018/7/26/4 > [5] https://www.spinics.net/lists/iommu/msg31874.html > > Cc: Ashok Raj > Cc: Jacob Pan > Cc: Kevin Tian > Cc: Liu Yi L > Suggested-by: Kevin Tian > Suggested-by: Jean-Philippe Brucker > Suggested-by: Joerg Roedel > Signed-off-by: Lu Baolu > --- >  drivers/iommu/iommu.c | 91 +++++++++++++++++++++++++++++++++++++++++++ >  include/linux/iommu.h | 70 +++++++++++++++++++++++++++++++++ >  2 files changed, 161 insertions(+) > > diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c > index 3ed4db334341..d0b323e8357f 100644 > --- a/drivers/iommu/iommu.c > +++ b/drivers/iommu/iommu.c > @@ -2033,3 +2033,94 @@ int iommu_fwspec_add_ids(struct device *dev, u32 > *ids, int num_ids) >          return 0; >  } >  EXPORT_SYMBOL_GPL(iommu_fwspec_add_ids); > + > +/* > + * Per device IOMMU features. > + */ > +bool iommu_dev_has_feature(struct device *dev, enum iommu_dev_features > feat) > +{ > +       const struct iommu_ops *ops = dev->bus->iommu_ops; > + > +       if (ops && ops->dev_has_feat) > +               return ops->dev_has_feat(dev, feat); > + > +       return false; > +} > +EXPORT_SYMBOL_GPL(iommu_dev_has_feature); > + > +int iommu_dev_enable_feature(struct device *dev, enum > iommu_dev_features feat) > +{ > +       const struct iommu_ops *ops = dev->bus->iommu_ops; > + > +       if (ops && ops->dev_enable_feat) > +               return ops->dev_enable_feat(dev, feat); > + > +       return -ENODEV; > +} > +EXPORT_SYMBOL_GPL(iommu_dev_enable_feature); > + > +int iommu_dev_disable_feature(struct device *dev, enum > iommu_dev_features feat) > +{ > +       const struct iommu_ops *ops = dev->bus->iommu_ops; > + > +       if (ops && ops->dev_disable_feat) > +               return ops->dev_disable_feat(dev, feat); > + > +       return -ENODEV; > +} > +EXPORT_SYMBOL_GPL(iommu_dev_disable_feature); > + > +bool iommu_dev_feature_enabled(struct device *dev, enum > iommu_dev_features feat) > +{ > +       const struct iommu_ops *ops = dev->bus->iommu_ops; > + > +       if (ops && ops->dev_feat_enabled) > +               return ops->dev_feat_enabled(dev, feat); > + > +       return false; > +} > +EXPORT_SYMBOL_GPL(iommu_dev_feature_enabled); > + > +/* > + * Aux-domain specific attach/detach. > + * > + * Only works if iommu_dev_has_feature(dev, IOMMU_DEV_FEAT_AUX) returns > true. Rather "Only works if iommu_dev_feature_enabled(dev, AUX) returns true"? > + * Also, as long as domains are attached to a device through this > interface, > + * any tries to call iommu_attach_device() should fail > (iommu_detach_device() > + * can't fail, so we fail on the tryint to re-attach). This should make "when trying to re-attach" > us safe > + * against a device being attached to a guest as a whole while there > are still > + * pasid users on it (aux and sva). A related question: is calling iommu_dev_disable_feat(dev, AUX) enough to detach all auxiliary domains? I guess device drivers will always need to tidy contexts up one by one, so maybe iommu_dev_disable_feat(dev, AUX) can return -EBUSY in this case? I think we need to specify this in a comment so device drivers know how to clean up. Thanks, Jean > + */ > +int iommu_aux_attach_device(struct iommu_domain *domain, struct device > *dev) > +{ > +       int ret = -ENODEV; > + > +       if (domain->ops->aux_attach_dev) > +               ret = domain->ops->aux_attach_dev(domain, dev); > + > +       if (!ret) > +               trace_attach_device_to_domain(dev); > + > +       return ret; > +} > +EXPORT_SYMBOL_GPL(iommu_aux_attach_device); > + > +void iommu_aux_detach_device(struct iommu_domain *domain, struct device > *dev) > +{ > +       if (domain->ops->aux_detach_dev) { > +               domain->ops->aux_detach_dev(domain, dev); > +               trace_detach_device_from_domain(dev); > +       } > +} > +EXPORT_SYMBOL_GPL(iommu_aux_detach_device); > + > +int iommu_aux_get_pasid(struct iommu_domain *domain, struct device *dev) > +{ > +       int ret = -ENODEV; > + > +       if (domain->ops->aux_get_pasid) > +               ret = domain->ops->aux_get_pasid(domain, dev); > + > +       return ret; > +} > +EXPORT_SYMBOL_GPL(iommu_aux_get_pasid); > diff --git a/include/linux/iommu.h b/include/linux/iommu.h > index e90da6b6f3d1..831eb29b35c5 100644 > --- a/include/linux/iommu.h > +++ b/include/linux/iommu.h > @@ -156,6 +156,11 @@ struct iommu_resv_region { >          enum iommu_resv_type    type; >  }; >   > +/* Per device IOMMU features */ > +enum iommu_dev_features { > +       IOMMU_DEV_FEAT_AUX,     /* Aux-domain feature */ > +}; > + >  #ifdef CONFIG_IOMMU_API >   >  /** > @@ -183,6 +188,11 @@ struct iommu_resv_region { >   * @domain_window_enable: Configure and enable a particular window for > a domain >   * @domain_window_disable: Disable a particular window for a domain >   * @of_xlate: add OF master IDs to iommu grouping > + * @dev_has/enable/disable_feat: per device entries to check/enable/disable > + *                               iommu specific features. > + * @dev_feat_enabled: check enabled feature > + * @aux_attach/detach_dev: aux-domain specific attach/detach entries. > + * @aux_get_pasid: get the pasid given an aux-domain >   * @pgsize_bitmap: bitmap of all possible supported page sizes >   */ >  struct iommu_ops { > @@ -226,6 +236,17 @@ struct iommu_ops { >          int (*of_xlate)(struct device *dev, struct of_phandle_args *args); >          bool (*is_attach_deferred)(struct iommu_domain *domain, struct > device *dev); >   > +       /* Per device IOMMU features */ > +       bool (*dev_has_feat)(struct device *dev, enum iommu_dev_features f); > +       bool (*dev_feat_enabled)(struct device *dev, enum > iommu_dev_features f); > +       int (*dev_enable_feat)(struct device *dev, enum > iommu_dev_features f); > +       int (*dev_disable_feat)(struct device *dev, enum > iommu_dev_features f); > + > +       /* Aux-domain specific attach/detach entries */ > +       int (*aux_attach_dev)(struct iommu_domain *domain, struct device > *dev); > +       void (*aux_detach_dev)(struct iommu_domain *domain, struct > device *dev); > +       int (*aux_get_pasid)(struct iommu_domain *domain, struct device > *dev); > + >          unsigned long pgsize_bitmap; >  }; >   > @@ -412,6 +433,14 @@ static inline void dev_iommu_fwspec_set(struct > device *dev, >  int iommu_probe_device(struct device *dev); >  void iommu_release_device(struct device *dev); >   > +bool iommu_dev_has_feature(struct device *dev, enum iommu_dev_features f); > +int iommu_dev_enable_feature(struct device *dev, enum > iommu_dev_features f); > +int iommu_dev_disable_feature(struct device *dev, enum > iommu_dev_features f); > +bool iommu_dev_feature_enabled(struct device *dev, enum > iommu_dev_features f); > +int iommu_aux_attach_device(struct iommu_domain *domain, struct device > *dev); > +void iommu_aux_detach_device(struct iommu_domain *domain, struct device > *dev); > +int iommu_aux_get_pasid(struct iommu_domain *domain, struct device *dev); > + >  #else /* CONFIG_IOMMU_API */ >   >  struct iommu_ops {}; > @@ -696,6 +725,47 @@ const struct iommu_ops > *iommu_ops_from_fwnode(struct fwnode_handle *fwnode) >          return NULL; >  } >   > +static inline bool > +iommu_dev_has_feature(struct device *dev, enum iommu_dev_features feat) > +{ > +       return false; > +} > + > +static inline bool > +iommu_dev_feature_enabled(struct device *dev, enum iommu_dev_features feat) > +{ > +       return false; > +} > + > +static inline int > +iommu_dev_enable_feature(struct device *dev, enum iommu_dev_features feat) > +{ > +       return -ENODEV; > +} > + > +static inline int > +iommu_dev_disable_feature(struct device *dev, enum iommu_dev_features feat) > +{ > +       return -ENODEV; > +} > + > +static inline int > +iommu_aux_attach_device(struct iommu_domain *domain, struct device *dev) > +{ > +       return -ENODEV; > +} > + > +static inline void > +iommu_aux_detach_device(struct iommu_domain *domain, struct device *dev) > +{ > +} > + > +static inline int > +iommu_aux_get_pasid(struct iommu_domain *domain, struct device *dev) > +{ > +       return -ENODEV; > +} > + >  #endif /* CONFIG_IOMMU_API */ >   >  #ifdef CONFIG_IOMMU_DEBUGFS > -- > 2.17.1 >