Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758584AbcJ1HhR (ORCPT ); Fri, 28 Oct 2016 03:37:17 -0400 Received: from mga01.intel.com ([192.55.52.88]:52252 "EHLO mga01.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752802AbcJ1HhP (ORCPT ); Fri, 28 Oct 2016 03:37:15 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.31,556,1473145200"; d="scan'208";a="184877127" Message-ID: <5812FF66.6020801@intel.com> Date: Fri, 28 Oct 2016 15:33:58 +0800 From: Jike Song User-Agent: Mozilla/5.0 (X11; Linux i686 on x86_64; rv:17.0) Gecko/20130801 Thunderbird/17.0.8 MIME-Version: 1.0 To: Kirti Wankhede CC: alex.williamson@redhat.com, pbonzini@redhat.com, kraxel@redhat.com, cjia@nvidia.com, qemu-devel@nongnu.org, kvm@vger.kernel.org, kevin.tian@intel.com, bjsdjshi@linux.vnet.ibm.com, linux-kernel@vger.kernel.org Subject: Re: [PATCH v10 10/19] vfio iommu: Add blocking notifier to notify DMA_UNMAP References: <1477517366-27871-1-git-send-email-kwankhede@nvidia.com> <1477517366-27871-11-git-send-email-kwankhede@nvidia.com> In-Reply-To: <1477517366-27871-11-git-send-email-kwankhede@nvidia.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 9640 Lines: 298 On 10/27/2016 05:29 AM, Kirti Wankhede wrote: > Added blocking notifier to IOMMU TYPE1 driver to notify vendor drivers > about DMA_UNMAP. > Exported two APIs vfio_register_notifier() and vfio_unregister_notifier(). > Vendor driver should register notifer using these APIs. > Vendor driver should use VFIO_IOMMU_NOTIFY_DMA_UNMAP action to invalidate > mappings. > > Signed-off-by: Kirti Wankhede > Signed-off-by: Neo Jia > Change-Id: I5910d0024d6be87f3e8d3e0ca0eaeaaa0b17f271 > --- > drivers/vfio/vfio.c | 73 +++++++++++++++++++++++++++++++++ > drivers/vfio/vfio_iommu_type1.c | 89 ++++++++++++++++++++++++++++++++++++----- > include/linux/vfio.h | 11 +++++ > 3 files changed, 163 insertions(+), 10 deletions(-) > > diff --git a/drivers/vfio/vfio.c b/drivers/vfio/vfio.c > index 28b50ca14c52..ff05ac6b1e90 100644 > --- a/drivers/vfio/vfio.c > +++ b/drivers/vfio/vfio.c > @@ -1891,6 +1891,79 @@ err_unpin_pages: > } > EXPORT_SYMBOL(vfio_unpin_pages); > > +int vfio_register_notifier(struct device *dev, struct notifier_block *nb) > +{ > + struct vfio_container *container; > + struct vfio_group *group; > + struct vfio_iommu_driver *driver; > + ssize_t ret; > + > + if (!dev || !nb) > + return -EINVAL; > + > + group = vfio_group_get_from_dev(dev); > + if (IS_ERR(group)) > + return PTR_ERR(group); > + > + ret = vfio_group_add_container_user(group); > + if (ret) > + goto err_register_nb; > + > + container = group->container; > + down_read(&container->group_lock); > + > + driver = container->iommu_driver; > + if (likely(driver && driver->ops->register_notifier)) > + ret = driver->ops->register_notifier(container->iommu_data, nb); > + else > + ret = -EINVAL; > + > + up_read(&container->group_lock); > + vfio_group_try_dissolve_container(group); > + > +err_register_nb: > + vfio_group_put(group); > + return ret; > +} > +EXPORT_SYMBOL(vfio_register_notifier); > + > +int vfio_unregister_notifier(struct device *dev, struct notifier_block *nb) > +{ > + struct vfio_container *container; > + struct vfio_group *group; > + struct vfio_iommu_driver *driver; > + ssize_t ret; > + > + if (!dev || !nb) > + return -EINVAL; > + > + group = vfio_group_get_from_dev(dev); > + if (IS_ERR(group)) > + return PTR_ERR(group); > + > + ret = vfio_group_add_container_user(group); > + if (ret) > + goto err_unregister_nb; > + > + container = group->container; > + down_read(&container->group_lock); > + > + driver = container->iommu_driver; > + if (likely(driver && driver->ops->unregister_notifier)) > + ret = driver->ops->unregister_notifier(container->iommu_data, > + nb); > + else > + ret = -EINVAL; > + > + up_read(&container->group_lock); > + vfio_group_try_dissolve_container(group); > + > +err_unregister_nb: > + vfio_group_put(group); > + return ret; > +} > +EXPORT_SYMBOL(vfio_unregister_notifier); > + > /** > * Module/class support > */ > diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c > index 5add11a147e1..a4bd331ac0fd 100644 > --- a/drivers/vfio/vfio_iommu_type1.c > +++ b/drivers/vfio/vfio_iommu_type1.c > @@ -37,6 +37,7 @@ > #include > #include > #include > +#include > > #define DRIVER_VERSION "0.2" > #define DRIVER_AUTHOR "Alex Williamson " > @@ -59,6 +60,7 @@ struct vfio_iommu { > struct vfio_domain *external_domain; /* domain for external user */ > struct mutex lock; > struct rb_root dma_list; > + struct blocking_notifier_head notifier; > bool v2; > bool nesting; > }; > @@ -549,7 +551,8 @@ static long vfio_iommu_type1_pin_pages(void *iommu_data, > > mutex_lock(&iommu->lock); > > - if (!iommu->external_domain) { > + /* Fail if notifier list is empty */ > + if ((!iommu->external_domain) || (!iommu->notifier.head)) { > ret = -EINVAL; > goto pin_done; > } > @@ -768,6 +771,50 @@ static unsigned long vfio_pgsize_bitmap(struct vfio_iommu *iommu) > return bitmap; > } > > +/* > + * This function finds pfn in domain->external_addr_space->pfn_list for given > + * iova range. If pfn exist, notify pfn to registered notifier list. On > + * receiving notifier callback, vendor driver should invalidate the mapping and > + * call vfio_unpin_pages() to unpin this pfn. With that vfio_pfn for this pfn > + * gets removed from rb tree of pfn_list. That re-arranges rb tree, so while > + * searching for next vfio_pfn in rb tree, start search from first node again. > + * If any vendor driver doesn't unpin that pfn, vfio_pfn would not get removed > + * from rb tree and so in next search vfio_pfn would be same as previous > + * vfio_pfn. In that case, exit from loop. > + */ > +static void vfio_notifier_call_chain(struct vfio_iommu *iommu, > + struct vfio_iommu_type1_dma_unmap *unmap) > +{ > + struct vfio_domain *domain = iommu->external_domain; > + struct rb_node *n; > + struct vfio_pfn *vpfn = NULL, *prev_vpfn; > + > + do { > + prev_vpfn = vpfn; > + mutex_lock(&domain->external_addr_space->pfn_list_lock); > + > + n = rb_first(&domain->external_addr_space->pfn_list); > + > + for (; n; n = rb_next(n), vpfn = NULL) { > + vpfn = rb_entry(n, struct vfio_pfn, node); > + > + if ((vpfn->iova >= unmap->iova) && > + (vpfn->iova < unmap->iova + unmap->size)) > + break; > + } > + > + mutex_unlock(&domain->external_addr_space->pfn_list_lock); > + > + /* Notify any listeners about DMA_UNMAP */ > + if (vpfn) > + blocking_notifier_call_chain(&iommu->notifier, > + VFIO_IOMMU_NOTIFY_DMA_UNMAP, > + &vpfn->pfn); Hi Kirti, The information carried by notifier is only a pfn. Since your pin/unpin interfaces design, it's the vendor driver who should guarantee pin/unpin same times. To achieve that, the vendor driver must cache it's iova->pfn mapping on its side, to avoid pinning a same page for multiple times. With the notifier carrying only a pfn, to find the iova by this pfn, the vendor driver must *also* keep a reverse-mapping. That's a bit too much. Since the vendor could also suffer from IOMMU-compatible problem, which means a local cache is always helpful, so I'd like to have the iova carried to the notifier. What'd you say? -- Thanks, Jike > + } while (vpfn && (prev_vpfn != vpfn)); > + > + WARN_ON(vpfn); > +} > + > static int vfio_dma_do_unmap(struct vfio_iommu *iommu, > struct vfio_iommu_type1_dma_unmap *unmap) > { > @@ -844,6 +891,9 @@ unlock: > /* Report how much was unmapped */ > unmap->size = unmapped; > > + if (unmapped && iommu->external_domain) > + vfio_notifier_call_chain(iommu, unmap); > + > return ret; > } > > @@ -1418,6 +1468,7 @@ static void *vfio_iommu_type1_open(unsigned long arg) > INIT_LIST_HEAD(&iommu->domain_list); > iommu->dma_list = RB_ROOT; > mutex_init(&iommu->lock); > + BLOCKING_INIT_NOTIFIER_HEAD(&iommu->notifier); > > return iommu; > } > @@ -1555,16 +1606,34 @@ static long vfio_iommu_type1_ioctl(void *iommu_data, > return -ENOTTY; > } > > +static int vfio_iommu_type1_register_notifier(void *iommu_data, > + struct notifier_block *nb) > +{ > + struct vfio_iommu *iommu = iommu_data; > + > + return blocking_notifier_chain_register(&iommu->notifier, nb); > +} > + > +static int vfio_iommu_type1_unregister_notifier(void *iommu_data, > + struct notifier_block *nb) > +{ > + struct vfio_iommu *iommu = iommu_data; > + > + return blocking_notifier_chain_unregister(&iommu->notifier, nb); > +} > + > static const struct vfio_iommu_driver_ops vfio_iommu_driver_ops_type1 = { > - .name = "vfio-iommu-type1", > - .owner = THIS_MODULE, > - .open = vfio_iommu_type1_open, > - .release = vfio_iommu_type1_release, > - .ioctl = vfio_iommu_type1_ioctl, > - .attach_group = vfio_iommu_type1_attach_group, > - .detach_group = vfio_iommu_type1_detach_group, > - .pin_pages = vfio_iommu_type1_pin_pages, > - .unpin_pages = vfio_iommu_type1_unpin_pages, > + .name = "vfio-iommu-type1", > + .owner = THIS_MODULE, > + .open = vfio_iommu_type1_open, > + .release = vfio_iommu_type1_release, > + .ioctl = vfio_iommu_type1_ioctl, > + .attach_group = vfio_iommu_type1_attach_group, > + .detach_group = vfio_iommu_type1_detach_group, > + .pin_pages = vfio_iommu_type1_pin_pages, > + .unpin_pages = vfio_iommu_type1_unpin_pages, > + .register_notifier = vfio_iommu_type1_register_notifier, > + .unregister_notifier = vfio_iommu_type1_unregister_notifier, > }; > > static int __init vfio_iommu_type1_init(void) > diff --git a/include/linux/vfio.h b/include/linux/vfio.h > index 0609a2052846..4c91ce8bfaeb 100644 > --- a/include/linux/vfio.h > +++ b/include/linux/vfio.h > @@ -80,6 +80,10 @@ struct vfio_iommu_driver_ops { > unsigned long *phys_pfn); > long (*unpin_pages)(void *iommu_data, unsigned long *pfn, > long npage); > + int (*register_notifier)(void *iommu_data, > + struct notifier_block *nb); > + int (*unregister_notifier)(void *iommu_data, > + struct notifier_block *nb); > }; > > extern int vfio_register_iommu_driver(const struct vfio_iommu_driver_ops *ops); > @@ -137,6 +141,13 @@ extern long vfio_pin_pages(struct device *dev, unsigned long *user_pfn, > extern long vfio_unpin_pages(struct device *dev, unsigned long *pfn, > long npage); > > +#define VFIO_IOMMU_NOTIFY_DMA_UNMAP 1 > + > +extern int vfio_register_notifier(struct device *dev, > + struct notifier_block *nb); > + > +extern int vfio_unregister_notifier(struct device *dev, > + struct notifier_block *nb); > /* > * IRQfd - generic > */ >