From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Return-Path: Subject: Re: [PATCH v2 01/40] iommu: Introduce Shared Virtual Addressing API To: Jean-Philippe Brucker , linux-arm-kernel@lists.infradead.org, linux-pci@vger.kernel.org, linux-acpi@vger.kernel.org, devicetree@vger.kernel.org, iommu@lists.linux-foundation.org, kvm@vger.kernel.org, linux-mm@kvack.org References: <20180511190641.23008-1-jean-philippe.brucker@arm.com> <20180511190641.23008-2-jean-philippe.brucker@arm.com> From: Auger Eric Message-ID: Date: Wed, 5 Sep 2018 13:29:10 +0200 MIME-Version: 1.0 In-Reply-To: <20180511190641.23008-2-jean-philippe.brucker@arm.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: xieyisheng1@huawei.com, ilias.apalodimas@linaro.org, xuzaibo@huawei.com, thunder.leizhen@huawei.com, will.deacon@arm.com, okaya@codeaurora.org, yi.l.liu@intel.com, ashok.raj@intel.com, tn@semihalf.com, joro@8bytes.org, bharatku@xilinx.com, liudongdong3@huawei.com, rfranz@cavium.com, kevin.tian@intel.com, jacob.jun.pan@linux.intel.com, alex.williamson@redhat.com, rgummal@xilinx.com, jonathan.cameron@huawei.com, shunyong.yang@hxt-semitech.com, dwmw2@infradead.org, liubo95@huawei.com, jcrouse@codeaurora.org, robdclark@gmail.com, robin.murphy@arm.com, christian.koenig@amd.com, nwatters@codeaurora.org, baolu.lu@linux.intel.com Content-Type: text/plain; charset="us-ascii" Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+bjorn=helgaas.com@lists.infradead.org List-ID: Hi Jean-Philippe, On 05/11/2018 09:06 PM, Jean-Philippe Brucker wrote: > Shared Virtual Addressing (SVA) provides a way for device drivers to bind > process address spaces to devices. This requires the IOMMU to support page > table format and features compatible with the CPUs, and usually requires > the system to support I/O Page Faults (IOPF) and Process Address Space ID > (PASID). When all of these are available, DMA can access virtual addresses > of a process. A PASID is allocated for each process, and the device driver > programs it into the device in an implementation-specific way. > > Add a new API for sharing process page tables with devices. Introduce two > IOMMU operations, sva_device_init() and sva_device_shutdown(), that > prepare the IOMMU driver for SVA. For example allocate PASID tables and > fault queues. Subsequent patches will implement the bind() and unbind() > operations. > > Support for I/O Page Faults will be added in a later patch using a new > feature bit (IOMMU_SVA_FEAT_IOPF). With the current API users must pin > down all shared mappings. Other feature bits that may be added in the > future are IOMMU_SVA_FEAT_PRIVATE, to support private PASID address > spaces, and IOMMU_SVA_FEAT_NO_PASID, to bind the whole device address > space to a process. > > Signed-off-by: Jean-Philippe Brucker > > --- > v1->v2: > * Add sva_param structure to iommu_param > * CONFIG option is only selectable by IOMMU drivers > --- > drivers/iommu/Kconfig | 4 ++ > drivers/iommu/Makefile | 1 + > drivers/iommu/iommu-sva.c | 110 ++++++++++++++++++++++++++++++++++++++ > include/linux/iommu.h | 32 +++++++++++ > 4 files changed, 147 insertions(+) > create mode 100644 drivers/iommu/iommu-sva.c > > diff --git a/drivers/iommu/Kconfig b/drivers/iommu/Kconfig > index 7564237f788d..cca8e06903c7 100644 > --- a/drivers/iommu/Kconfig > +++ b/drivers/iommu/Kconfig > @@ -74,6 +74,10 @@ config IOMMU_DMA > select IOMMU_IOVA > select NEED_SG_DMA_LENGTH > > +config IOMMU_SVA > + bool > + select IOMMU_API > + > config FSL_PAMU > bool "Freescale IOMMU support" > depends on PCI > diff --git a/drivers/iommu/Makefile b/drivers/iommu/Makefile > index 1fb695854809..1dbcc89ebe4c 100644 > --- a/drivers/iommu/Makefile > +++ b/drivers/iommu/Makefile > @@ -3,6 +3,7 @@ obj-$(CONFIG_IOMMU_API) += iommu.o > obj-$(CONFIG_IOMMU_API) += iommu-traces.o > obj-$(CONFIG_IOMMU_API) += iommu-sysfs.o > obj-$(CONFIG_IOMMU_DMA) += dma-iommu.o > +obj-$(CONFIG_IOMMU_SVA) += iommu-sva.o > obj-$(CONFIG_IOMMU_IO_PGTABLE) += io-pgtable.o > obj-$(CONFIG_IOMMU_IO_PGTABLE_ARMV7S) += io-pgtable-arm-v7s.o > obj-$(CONFIG_IOMMU_IO_PGTABLE_LPAE) += io-pgtable-arm.o > diff --git a/drivers/iommu/iommu-sva.c b/drivers/iommu/iommu-sva.c > new file mode 100644 > index 000000000000..8b4afb7c63ae > --- /dev/null > +++ b/drivers/iommu/iommu-sva.c > @@ -0,0 +1,110 @@ > +// SPDX-License-Identifier: GPL-2.0 > +/* > + * Manage PASIDs and bind process address spaces to devices. > + * > + * Copyright (C) 2018 ARM Ltd. > + */ > + > +#include > +#include > + > +/** > + * iommu_sva_device_init() - Initialize Shared Virtual Addressing for a device > + * @dev: the device > + * @features: bitmask of features that need to be initialized > + * @max_pasid: max PASID value supported by the device > + * > + * Users of the bind()/unbind() API must call this function to initialize all > + * features required for SVA. > + * > + * The device must support multiple address spaces (e.g. PCI PASID). By default > + * the PASID allocated during bind() is limited by the IOMMU capacity, and by > + * the device PASID width defined in the PCI capability or in the firmware > + * description. Setting @max_pasid to a non-zero value smaller than this limit > + * overrides it. > + * > + * The device should not be performing any DMA while this function is running, > + * otherwise the behavior is undefined. > + * > + * Return 0 if initialization succeeded, or an error. > + */ > +int iommu_sva_device_init(struct device *dev, unsigned long features, > + unsigned int max_pasid) what about min_pasid? > +{ > + int ret; > + struct iommu_sva_param *param; > + struct iommu_domain *domain = iommu_get_domain_for_dev(dev); > + > + if (!domain || !domain->ops->sva_device_init) > + return -ENODEV; > + > + if (features) > + return -EINVAL; > + > + param = kzalloc(sizeof(*param), GFP_KERNEL); > + if (!param) > + return -ENOMEM; > + > + param->features = features; > + param->max_pasid = max_pasid; > + > + /* > + * IOMMU driver updates the limits depending on the IOMMU and device > + * capabilities. > + */ > + ret = domain->ops->sva_device_init(dev, param); > + if (ret) > + goto err_free_param; So you are likely to call sva_device_init even if it was already called (ie. dev->iommu_param->sva_param is already set). Can't you test whether dev->iommu_param->sva_param is already set first? > + > + mutex_lock(&dev->iommu_param->lock); > + if (dev->iommu_param->sva_param) > + ret = -EEXIST; > + else > + dev->iommu_param->sva_param = param; > + mutex_unlock(&dev->iommu_param->lock); > + if (ret) > + goto err_device_shutdown; > + > + return 0; > + > +err_device_shutdown: > + if (domain->ops->sva_device_shutdown) > + domain->ops->sva_device_shutdown(dev, param); > + > +err_free_param: > + kfree(param); > + > + return ret; > +} > +EXPORT_SYMBOL_GPL(iommu_sva_device_init); > + > +/** > + * iommu_sva_device_shutdown() - Shutdown Shared Virtual Addressing for a device > + * @dev: the device > + * > + * Disable SVA. Device driver should ensure that the device isn't performing any > + * DMA while this function is running. > + */ > +int iommu_sva_device_shutdown(struct device *dev) Not sure the returned value is required for a shutdown operation. > +{ > + struct iommu_sva_param *param; > + struct iommu_domain *domain = iommu_get_domain_for_dev(dev); > + > + if (!domain) > + return -ENODEV; > + > + mutex_lock(&dev->iommu_param->lock); > + param = dev->iommu_param->sva_param; > + dev->iommu_param->sva_param = NULL; > + mutex_unlock(&dev->iommu_param->lock); > + if (!param) > + return -ENODEV; > + > + if (domain->ops->sva_device_shutdown) > + domain->ops->sva_device_shutdown(dev, param); > + > + kfree(param); > + > + return 0; > +} > +EXPORT_SYMBOL_GPL(iommu_sva_device_shutdown); > diff --git a/include/linux/iommu.h b/include/linux/iommu.h > index 0933f726d2e6..2efe7738bedb 100644 > --- a/include/linux/iommu.h > +++ b/include/linux/iommu.h > @@ -212,6 +212,12 @@ struct page_response_msg { > u64 private_data; > }; > > +struct iommu_sva_param { What are the feature values? > + unsigned long features; > + unsigned int min_pasid; > + unsigned int max_pasid; > +}; > + > /** > * struct iommu_ops - iommu ops and capabilities > * @capable: check capability > @@ -219,6 +225,8 @@ struct page_response_msg { > * @domain_free: free iommu domain > * @attach_dev: attach device to an iommu domain > * @detach_dev: detach device from an iommu domain > + * @sva_device_init: initialize Shared Virtual Adressing for a device Addressing > + * @sva_device_shutdown: shutdown Shared Virtual Adressing for a device Addressing > * @map: map a physically contiguous memory region to an iommu domain > * @unmap: unmap a physically contiguous memory region from an iommu domain > * @map_sg: map a scatter-gather list of physically contiguous memory chunks > @@ -256,6 +264,10 @@ struct iommu_ops { > > int (*attach_dev)(struct iommu_domain *domain, struct device *dev); > void (*detach_dev)(struct iommu_domain *domain, struct device *dev); > + int (*sva_device_init)(struct device *dev, > + struct iommu_sva_param *param); > + void (*sva_device_shutdown)(struct device *dev, > + struct iommu_sva_param *param); > int (*map)(struct iommu_domain *domain, unsigned long iova, > phys_addr_t paddr, size_t size, int prot); > size_t (*unmap)(struct iommu_domain *domain, unsigned long iova, > @@ -413,6 +425,7 @@ struct iommu_fault_param { > * struct iommu_param - collection of per-device IOMMU data > * > * @fault_param: IOMMU detected device fault reporting data > + * @sva_param: SVA parameters > * > * TODO: migrate other per device data pointers under iommu_dev_data, e.g. > * struct iommu_group *iommu_group; > @@ -421,6 +434,7 @@ struct iommu_fault_param { > struct iommu_param { > struct mutex lock; > struct iommu_fault_param *fault_param; > + struct iommu_sva_param *sva_param; > }; > > int iommu_device_register(struct iommu_device *iommu); > @@ -920,4 +934,22 @@ static inline int iommu_sva_invalidate(struct iommu_domain *domain, > > #endif /* CONFIG_IOMMU_API */ > > +#ifdef CONFIG_IOMMU_SVA > +extern int iommu_sva_device_init(struct device *dev, unsigned long features, > + unsigned int max_pasid); > +extern int iommu_sva_device_shutdown(struct device *dev); > +#else /* CONFIG_IOMMU_SVA */ > +static inline int iommu_sva_device_init(struct device *dev, > + unsigned long features, > + unsigned int max_pasid) > +{ > + return -ENODEV; > +} > + > +static inline int iommu_sva_device_shutdown(struct device *dev) > +{ > + return -ENODEV; > +} > +#endif /* CONFIG_IOMMU_SVA */ > + > #endif /* __LINUX_IOMMU_H */ > Thanks Eric _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel