Message-ID: <e4f28607-8235-7a66-15ec-379bb559b0fd@redhat.com>
Date:   Wed, 15 Apr 2020 18:02:34 +0200
From:   Auger Eric <eric.auger@...hat.com>
To:     Jacob Pan <jacob.jun.pan@...ux.intel.com>
Cc:     eric.auger.pro@...il.com, iommu@...ts.linux-foundation.org,
        linux-kernel@...r.kernel.org, kvm@...r.kernel.org,
        kvmarm@...ts.cs.columbia.edu, will@...nel.org, joro@...tes.org,
        maz@...nel.org, robin.murphy@....com, jean-philippe@...aro.org,
        zhangfei.gao@...aro.org, shameerali.kolothum.thodi@...wei.com,
        alex.williamson@...hat.com, yi.l.liu@...el.com,
        peter.maydell@...aro.org, zhangfei.gao@...il.com, tn@...ihalf.com,
        zhangfei.gao@...mail.com, bbhushan2@...vell.com
Subject: Re: [PATCH v11 01/13] iommu: Introduce attach/detach_pasid_table API

Hi Jacob,

On 4/15/20 5:59 PM, Jacob Pan wrote:
> On Wed, 15 Apr 2020 16:52:10 +0200
> Auger Eric <eric.auger@...hat.com> wrote:
> 
>> Hi Jacob,
>> On 4/15/20 12:15 AM, Jacob Pan wrote:
>>> Hi Eric,
>>>
>>> There are some discussions about how to size the uAPI data.
>>> https://lkml.org/lkml/2020/4/14/939
>>>
>>> I think the problem with the current scheme is that when uAPI data
>>> gets extended, if VFIO continue to use:
>>>
>>> minsz = offsetofend(struct vfio_iommu_type1_set_pasid_table,
>>> config); if (copy_from_user(&spt, (void __user *)arg, minsz))
>>>
>>> It may copy more data from user than what was setup by the user.
>>>
>>> So, as suggested by Alex, we could add argsz to the IOMMU uAPI
>>> struct. So if argsz > minsz, then fail the attach_table since
>>> kernel might be old, doesn't know about the extra data.
>>> If argsz <= minsz, kernel can support the attach_table but must
>>> process the data based on flags or config.  
>>
>> So I guess we would need both an argsz _u32 + a new flag _u32 right?
>>
> Yes.
>> I am ok with that idea. Besides how will you manage for existing IOMMU
>> UAPIs?
> I plan to add argsz and flags (if not already have one)
> 
>> At some point you envisionned to have a getter at iommu api
>> level to retrieve the size of a structure for a given version, right?
>>
> This idea is shot down. There is no version-size lookup.
> So the current plan is for user to fill out argsz in each IOMMU uAPI
> struct. VFIO does the copy_from_user() based on argsz (sanitized
> against the size of current kernel struct).
> 
> IOMMU vendor driver process the data based on flags which indicates
> new capability/extensions.
OK. Sounds sensible

Thanks

Eric
> 
>> Thanks
>>
>> Eric
>>>
>>> Does it make sense to you?
>>>
>>>
>>> On Tue, 14 Apr 2020 17:05:55 +0200
>>> Eric Auger <eric.auger@...hat.com> wrote:
>>>   
>>>> From: Jacob Pan <jacob.jun.pan@...ux.intel.com>
>>>>
>>>> In virtualization use case, when a guest is assigned
>>>> a PCI host device, protected by a virtual IOMMU on the guest,
>>>> the physical IOMMU must be programmed to be consistent with
>>>> the guest mappings. If the physical IOMMU supports two
>>>> translation stages it makes sense to program guest mappings
>>>> onto the first stage/level (ARM/Intel terminology) while the host
>>>> owns the stage/level 2.
>>>>
>>>> In that case, it is mandated to trap on guest configuration
>>>> settings and pass those to the physical iommu driver.
>>>>
>>>> This patch adds a new API to the iommu subsystem that allows
>>>> to set/unset the pasid table information.
>>>>
>>>> A generic iommu_pasid_table_config struct is introduced in
>>>> a new iommu.h uapi header. This is going to be used by the VFIO
>>>> user API.
>>>>
>>>> Signed-off-by: Jean-Philippe Brucker
>>>> <jean-philippe.brucker@....com> Signed-off-by: Liu, Yi L
>>>> <yi.l.liu@...ux.intel.com> Signed-off-by: Ashok Raj
>>>> <ashok.raj@...el.com> Signed-off-by: Jacob Pan
>>>> <jacob.jun.pan@...ux.intel.com> Signed-off-by: Eric Auger
>>>> <eric.auger@...hat.com> Reviewed-by: Jean-Philippe Brucker
>>>> <jean-philippe.brucker@....com> ---
>>>>  drivers/iommu/iommu.c      | 19 ++++++++++++++
>>>>  include/linux/iommu.h      | 18 ++++++++++++++
>>>>  include/uapi/linux/iommu.h | 51
>>>> ++++++++++++++++++++++++++++++++++++++ 3 files changed, 88
>>>> insertions(+)
>>>>
>>>> diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
>>>> index 2b471419e26c..b71ad56f8c99 100644
>>>> --- a/drivers/iommu/iommu.c
>>>> +++ b/drivers/iommu/iommu.c
>>>> @@ -1723,6 +1723,25 @@ int iommu_sva_unbind_gpasid(struct
>>>> iommu_domain *domain, struct device *dev, }
>>>>  EXPORT_SYMBOL_GPL(iommu_sva_unbind_gpasid);
>>>>  
>>>> +int iommu_attach_pasid_table(struct iommu_domain *domain,
>>>> +			     struct iommu_pasid_table_config *cfg)
>>>> +{
>>>> +	if (unlikely(!domain->ops->attach_pasid_table))
>>>> +		return -ENODEV;
>>>> +
>>>> +	return domain->ops->attach_pasid_table(domain, cfg);
>>>> +}
>>>> +EXPORT_SYMBOL_GPL(iommu_attach_pasid_table);
>>>> +
>>>> +void iommu_detach_pasid_table(struct iommu_domain *domain)
>>>> +{
>>>> +	if (unlikely(!domain->ops->detach_pasid_table))
>>>> +		return;
>>>> +
>>>> +	domain->ops->detach_pasid_table(domain);
>>>> +}
>>>> +EXPORT_SYMBOL_GPL(iommu_detach_pasid_table);
>>>> +
>>>>  static void __iommu_detach_device(struct iommu_domain *domain,
>>>>  				  struct device *dev)
>>>>  {
>>>> diff --git a/include/linux/iommu.h b/include/linux/iommu.h
>>>> index 7ef8b0bda695..3e1057c3585a 100644
>>>> --- a/include/linux/iommu.h
>>>> +++ b/include/linux/iommu.h
>>>> @@ -248,6 +248,8 @@ struct iommu_iotlb_gather {
>>>>   * @cache_invalidate: invalidate translation caches
>>>>   * @sva_bind_gpasid: bind guest pasid and mm
>>>>   * @sva_unbind_gpasid: unbind guest pasid and mm
>>>> + * @attach_pasid_table: attach a pasid table
>>>> + * @detach_pasid_table: detach the pasid table
>>>>   * @pgsize_bitmap: bitmap of all possible supported page sizes
>>>>   * @owner: Driver module providing these ops
>>>>   */
>>>> @@ -307,6 +309,9 @@ struct iommu_ops {
>>>>  				      void *drvdata);
>>>>  	void (*sva_unbind)(struct iommu_sva *handle);
>>>>  	int (*sva_get_pasid)(struct iommu_sva *handle);
>>>> +	int (*attach_pasid_table)(struct iommu_domain *domain,
>>>> +				  struct iommu_pasid_table_config
>>>> *cfg);
>>>> +	void (*detach_pasid_table)(struct iommu_domain *domain);
>>>>  
>>>>  	int (*page_response)(struct device *dev,
>>>>  			     struct iommu_fault_event *evt,
>>>> @@ -446,6 +451,9 @@ extern int iommu_sva_bind_gpasid(struct
>>>> iommu_domain *domain, struct device *dev, struct
>>>> iommu_gpasid_bind_data *data); extern int
>>>> iommu_sva_unbind_gpasid(struct iommu_domain *domain, struct device
>>>> *dev, ioasid_t pasid); +extern int iommu_attach_pasid_table(struct
>>>> iommu_domain *domain,
>>>> +				    struct
>>>> iommu_pasid_table_config *cfg); +extern void
>>>> iommu_detach_pasid_table(struct iommu_domain *domain); extern
>>>> struct iommu_domain *iommu_get_domain_for_dev(struct device *dev);
>>>> extern struct iommu_domain *iommu_get_dma_domain(struct device
>>>> *dev); extern int iommu_map(struct iommu_domain *domain, unsigned
>>>> long iova, @@ -1048,6 +1056,16 @@ iommu_aux_get_pasid(struct
>>>> iommu_domain *domain, struct device *dev) return -ENODEV; }
>>>>  
>>>> +static inline
>>>> +int iommu_attach_pasid_table(struct iommu_domain *domain,
>>>> +			     struct iommu_pasid_table_config *cfg)
>>>> +{
>>>> +	return -ENODEV;
>>>> +}
>>>> +
>>>> +static inline
>>>> +void iommu_detach_pasid_table(struct iommu_domain *domain) {}
>>>> +
>>>>  static inline struct iommu_sva *
>>>>  iommu_sva_bind_device(struct device *dev, struct mm_struct *mm,
>>>> void *drvdata) {
>>>> diff --git a/include/uapi/linux/iommu.h
>>>> b/include/uapi/linux/iommu.h index 4ad3496e5c43..8d00be10dc6d
>>>> 100644 --- a/include/uapi/linux/iommu.h
>>>> +++ b/include/uapi/linux/iommu.h
>>>> @@ -321,4 +321,55 @@ struct iommu_gpasid_bind_data {
>>>>  	};
>>>>  };
>>>>  
>>>> +/**
>>>> + * struct iommu_pasid_smmuv3 - ARM SMMUv3 Stream Table Entry
>>>> stage 1 related
>>>> + *     information
>>>> + * @version: API version of this structure
>>>> + * @s1fmt: STE s1fmt (format of the CD table: single CD, linear
>>>> table
>>>> + *         or 2-level table)
>>>> + * @s1dss: STE s1dss (specifies the behavior when @pasid_bits != 0
>>>> + *         and no PASID is passed along with the incoming
>>>> transaction)
>>>> + * @padding: reserved for future use (should be zero)
>>>> + *
>>>> + * The PASID table is referred to as the Context Descriptor (CD)
>>>> table on ARM
>>>> + * SMMUv3. Please refer to the ARM SMMU 3.x spec (ARM IHI 0070A)
>>>> for full
>>>> + * details.
>>>> + */
>>>> +struct iommu_pasid_smmuv3 {
>>>> +#define PASID_TABLE_SMMUV3_CFG_VERSION_1 1
>>>> +	__u32	version;
>>>> +	__u8	s1fmt;
>>>> +	__u8	s1dss;
>>>> +	__u8	padding[2];
>>>> +};
>>>> +
>>>> +/**
>>>> + * struct iommu_pasid_table_config - PASID table data used to bind
>>>> guest PASID
>>>> + *     table to the host IOMMU
>>>> + * @version: API version to prepare for future extensions
>>>> + * @format: format of the PASID table
>>>> + * @base_ptr: guest physical address of the PASID table
>>>> + * @pasid_bits: number of PASID bits used in the PASID table
>>>> + * @config: indicates whether the guest translation stage must
>>>> + *          be translated, bypassed or aborted.
>>>> + * @padding: reserved for future use (should be zero)
>>>> + * @smmuv3: table information when @format is
>>>> %IOMMU_PASID_FORMAT_SMMUV3
>>>> + */
>>>> +struct iommu_pasid_table_config {
>>>> +#define PASID_TABLE_CFG_VERSION_1 1
>>>> +	__u32	version;
>>>> +#define IOMMU_PASID_FORMAT_SMMUV3	1
>>>> +	__u32	format;
>>>> +	__u64	base_ptr;
>>>> +	__u8	pasid_bits;
>>>> +#define IOMMU_PASID_CONFIG_TRANSLATE	1
>>>> +#define IOMMU_PASID_CONFIG_BYPASS	2
>>>> +#define IOMMU_PASID_CONFIG_ABORT	3
>>>> +	__u8	config;
>>>> +	__u8    padding[6];
>>>> +	union {
>>>> +		struct iommu_pasid_smmuv3 smmuv3;
>>>> +	};
>>>> +};
>>>> +
>>>>  #endif /* _UAPI_IOMMU_H */  
>>>
>>> [Jacob Pan]
>>>   
>>
> 
> [Jacob Pan]
> 

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