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Date: Mon, 26 Nov 2018 10:04:30 +0800
From: Lu Baolu <baolu.lu@...ux.intel.com>
To: Auger Eric <eric.auger@...hat.com>, Joerg Roedel <joro@...tes.org>,
David Woodhouse <dwmw2@...radead.org>,
Alex Williamson <alex.williamson@...hat.com>,
Kirti Wankhede <kwankhede@...dia.com>
Cc: baolu.lu@...ux.intel.com, kevin.tian@...el.com,
ashok.raj@...el.com, tiwei.bie@...el.com,
Jean-Philippe Brucker <jean-philippe.brucker@....com>,
sanjay.k.kumar@...el.com, iommu@...ts.linux-foundation.org,
linux-kernel@...r.kernel.org, yi.y.sun@...el.com,
jacob.jun.pan@...el.com, kvm@...r.kernel.org
Subject: Re: [PATCH v4 1/8] iommu: Add APIs for multiple domains per device
Hi Eric,
On 11/23/18 6:50 PM, Auger Eric wrote:
> Hi Lu,
>
> On 11/5/18 8:34 AM, 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. 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 includes:
>>
>> * iommu_get_dev_attr(dev, IOMMU_DEV_ATTR_AUXD_CAPABILITY)
>> - Represents the ability of supporting multiple domains
>> per device.
>>
>> * iommu_get_dev_attr(dev, IOMMU_DEV_ATTR_AUXD_ENABLED)
>> - Checks whether the device identified by @dev is working
>> in auxiliary mode.
>>
>> * iommu_set_dev_attr(dev, IOMMU_DEV_ATTR_AUXD_ENABLE)
>> - Enables the multiple domains capability for the device
>> referenced by @dev.
>>
>> * iommu_set_dev_attr(dev, IOMMU_DEV_ATTR_AUXD_DISABLE)
>> - Disables the multiple domains capability for the device
>> referenced by @dev.
>>
>> * iommu_attach_device_aux(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_detach_device_aux(domain, dev)
>> - Detach @domain which has been attached to @dev in the
>> auxiliary mode.
>>
>> * iommu_domain_get_attr(domain, DOMAIN_ATTR_AUXD_ID)
>> - Return ID used for finer-granularity DMA translation.
>> For the Intel Scalable IOV usage model, this will be
>> a PASID. The device which supports Scalalbe IOV needs
> s/Scalalbe/Scalable
>> to writes this ID to the device register so that DMA
> s/writes/write
Yes and thanks.
>> requests could be tagged with a right PASID prefix.
> This is not crystal clear to me as the intel implementation returns the
> default PASID and not the PASID of the aux domain.
The PASID of the aux domain is called default PASID.
>>
>> Many people involved in discussions of this design.
>>
>> Kevin Tian <kevin.tian@...el.com>
>> Liu Yi L <yi.l.liu@...el.com>
>> Ashok Raj <ashok.raj@...el.com>
>> Sanjay Kumar <sanjay.k.kumar@...el.com>
>> Jacob Pan <jacob.jun.pan@...ux.intel.com>
>> Alex Williamson <alex.williamson@...hat.com>
>> Jean-Philippe Brucker <jean-philippe.brucker@....com>
>>
>> and some discussions can be found here [4].
>>
>> [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
>>
>> Cc: Ashok Raj <ashok.raj@...el.com>
>> Cc: Jacob Pan <jacob.jun.pan@...ux.intel.com>
>> Cc: Kevin Tian <kevin.tian@...el.com>
>> Cc: Liu Yi L <yi.l.liu@...el.com>
>> Suggested-by: Kevin Tian <kevin.tian@...el.com>
>> Suggested-by: Jean-Philippe Brucker <jean-philippe.brucker@....com>
>> Signed-off-by: Lu Baolu <baolu.lu@...ux.intel.com>
>> ---
>> drivers/iommu/iommu.c | 52 +++++++++++++++++++++++++++++++++++++++++++
>> include/linux/iommu.h | 52 +++++++++++++++++++++++++++++++++++++++++++
>> 2 files changed, 104 insertions(+)
>>
>> diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
>> index edbdf5d6962c..0b7c96d1425e 100644
>> --- a/drivers/iommu/iommu.c
>> +++ b/drivers/iommu/iommu.c
>> @@ -2030,3 +2030,55 @@ int iommu_fwspec_add_ids(struct device *dev, u32 *ids, int num_ids)
>> return 0;
>> }
>> EXPORT_SYMBOL_GPL(iommu_fwspec_add_ids);
>> +
>> +/*
>> + * Generic interfaces to get or set per device IOMMU attributions.
>> + */
>> +int iommu_get_dev_attr(struct device *dev, enum iommu_dev_attr attr, void *data)
>> +{
>> + const struct iommu_ops *ops = dev->bus->iommu_ops;
>> +
>> + if (ops && ops->get_dev_attr)
>> + return ops->get_dev_attr(dev, attr, data);
>> +
>> + return -EINVAL;
>> +}
>> +EXPORT_SYMBOL_GPL(iommu_get_dev_attr);
>> +
>> +int iommu_set_dev_attr(struct device *dev, enum iommu_dev_attr attr, void *data)
>> +{
>> + const struct iommu_ops *ops = dev->bus->iommu_ops;
>> +
>> + if (ops && ops->set_dev_attr)
>> + return ops->set_dev_attr(dev, attr, data);
>> +
>> + return -EINVAL;
>> +}
>> +EXPORT_SYMBOL_GPL(iommu_set_dev_attr);
>> +
>> +/*
>> + * APIs to attach/detach a domain to/from a device in the
>> + * auxiliary mode.
>> + */
>> +int iommu_attach_device_aux(struct iommu_domain *domain, struct device *dev)
>> +{
>> + int ret = -ENODEV;
>> +
>> + if (domain->ops->attach_dev_aux)
>> + ret = domain->ops->attach_dev_aux(domain, dev);
>> +
>> + if (!ret)
>> + trace_attach_device_to_domain(dev);
>> +
>> + return ret;
>> +}
>> +EXPORT_SYMBOL_GPL(iommu_attach_device_aux);
>> +
>> +void iommu_detach_device_aux(struct iommu_domain *domain, struct device *dev)
>> +{
>> + if (domain->ops->detach_dev_aux) {
>> + domain->ops->detach_dev_aux(domain, dev);
>> + trace_detach_device_from_domain(dev);
>> + }
>> +}
>> +EXPORT_SYMBOL_GPL(iommu_detach_device_aux);
>> diff --git a/include/linux/iommu.h b/include/linux/iommu.h
>> index a1d28f42cb77..9bf1b3f2457a 100644
>> --- a/include/linux/iommu.h
>> +++ b/include/linux/iommu.h
>> @@ -126,6 +126,7 @@ enum iommu_attr {
>> DOMAIN_ATTR_NESTING, /* two stages of translation */
>> DOMAIN_ATTR_DMA_USE_FLUSH_QUEUE,
>> DOMAIN_ATTR_MAX,
>> + DOMAIN_ATTR_AUXD_ID,
>> };
>>
>> /* These are the possible reserved region types */
>> @@ -156,6 +157,14 @@ struct iommu_resv_region {
>> enum iommu_resv_type type;
>> };
>>
>> +/* Per device IOMMU attributions */
>> +enum iommu_dev_attr {
>> + IOMMU_DEV_ATTR_AUXD_CAPABILITY,
>> + IOMMU_DEV_ATTR_AUXD_ENABLED,
>> + IOMMU_DEV_ATTR_AUXD_ENABLE,
>> + IOMMU_DEV_ATTR_AUXD_DISABLE,
>> +};
>> +
>> #ifdef CONFIG_IOMMU_API
>>
>> /**
>> @@ -183,6 +192,8 @@ 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
>> + * @get_dev_attr: get per device IOMMU attributions
> s/attributions/attributes here and other locations?
Yes. It should be "attributes". Thanks.
>> + * @set_dev_attr: set per device IOMMU attributions
>> * @pgsize_bitmap: bitmap of all possible supported page sizes
>> */
>> struct iommu_ops {
>> @@ -226,6 +237,15 @@ 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);
>>
>> + /* Get/set per device IOMMU attributions */
>> + int (*get_dev_attr)(struct device *dev,
>> + enum iommu_dev_attr attr, void *data);
>> + int (*set_dev_attr)(struct device *dev,
>> + enum iommu_dev_attr attr, void *data);
>> + /* Attach/detach aux domain */
>> + int (*attach_dev_aux)(struct iommu_domain *domain, struct device *dev);
>> + void (*detach_dev_aux)(struct iommu_domain *domain, struct device *dev);
>> +
>> unsigned long pgsize_bitmap;
>> };
>>
>> @@ -398,6 +418,16 @@ void iommu_fwspec_free(struct device *dev);
>> int iommu_fwspec_add_ids(struct device *dev, u32 *ids, int num_ids);
>> const struct iommu_ops *iommu_ops_from_fwnode(struct fwnode_handle *fwnode);
>>
>> +int iommu_get_dev_attr(struct device *dev,
>> + enum iommu_dev_attr attr, void *data);
>> +int iommu_set_dev_attr(struct device *dev,
>> + enum iommu_dev_attr attr, void *data);
>> +
>> +extern int iommu_attach_device_aux(struct iommu_domain *domain,
>> + struct device *dev);
>> +extern void iommu_detach_device_aux(struct iommu_domain *domain,
>> + struct device *dev);
>> +
>> #else /* CONFIG_IOMMU_API */
>>
>> struct iommu_ops {};
>> @@ -682,6 +712,28 @@ const struct iommu_ops *iommu_ops_from_fwnode(struct fwnode_handle *fwnode)
>> return NULL;
>> }
>>
>> +static inline int
>> +iommu_get_dev_attr(struct device *dev, enum iommu_dev_attr attr, void *data)
>> +{
>> + return -EINVAL;
>> +}
>> +
>> +static inline int
>> +iommu_set_dev_attr(struct device *dev, enum iommu_dev_attr attr, void *data)
>> +{
>> + return -EINVAL;
>> +}
>> +
>> +static inline int
>> +iommu_attach_device_aux(struct iommu_domain *domain, struct device *dev)
>> +{
>> + return -ENODEV;
>> +}
>> +
>> +static inline void
>> +iommu_detach_device_aux(struct iommu_domain *domain, struct device *dev)
>> +{
>> +}
>> #endif /* CONFIG_IOMMU_API */
>>
>> #ifdef CONFIG_IOMMU_DEBUGFS
>>
>
> Thanks
>
> Eric
>
Best regards,
Lu Baolu
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