Re: [PATCH v13 01/15] iommu: Introduce attach/detach_pasid_table API

From: Auger Eric
Date: Thu Nov 19 2020 - 12:03:18 EST

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In reply to: Jacob Pan: "Re: [PATCH v13 01/15] iommu: Introduce attach/detach_pasid_table API"
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Hi Jacob,
On 11/18/20 5:19 PM, Jacob Pan wrote:
> Hi Eric,
>
> On Wed, 18 Nov 2020 12:21:37 +0100, Eric Auger <eric.auger@xxxxxxxxxx>
> wrote:
>
>> 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@xxxxxxx>
>> Signed-off-by: Liu, Yi L <yi.l.liu@xxxxxxxxxxxxxxx>
>> Signed-off-by: Ashok Raj <ashok.raj@xxxxxxxxx>
>> Signed-off-by: Jacob Pan <jacob.jun.pan@xxxxxxxxxxxxxxx>
>> Signed-off-by: Eric Auger <eric.auger@xxxxxxxxxx>
>>
>> ---
>>
>> v12 -> v13:
>> - Fix config check
>>
>> v11 -> v12:
>> - add argsz, name the union
>> ---
>> drivers/iommu/iommu.c | 68 ++++++++++++++++++++++++++++++++++++++
>> include/linux/iommu.h | 21 ++++++++++++
>> include/uapi/linux/iommu.h | 54 ++++++++++++++++++++++++++++++
>> 3 files changed, 143 insertions(+)
>>
>> diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
>> index b53446bb8c6b..978fe34378fb 100644
>> --- a/drivers/iommu/iommu.c
>> +++ b/drivers/iommu/iommu.c
>> @@ -2171,6 +2171,74 @@ int iommu_uapi_sva_unbind_gpasid(struct
>> iommu_domain *domain, struct device *dev }
>> EXPORT_SYMBOL_GPL(iommu_uapi_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);
>> +}
>> +
>> +int iommu_uapi_attach_pasid_table(struct iommu_domain *domain,
>> + void __user *uinfo)
>> +{
>> + struct iommu_pasid_table_config pasid_table_data = { 0 };
>> + u32 minsz;
>> +
>> + if (unlikely(!domain->ops->attach_pasid_table))
>> + return -ENODEV;
>> +
>> + /*
>> + * No new spaces can be added before the variable sized union,
>> the
>> + * minimum size is the offset to the union.
>> + */
>> + minsz = offsetof(struct iommu_pasid_table_config, vendor_data);
>> +
>> + /* Copy minsz from user to get flags and argsz */
>> + if (copy_from_user(&pasid_table_data, uinfo, minsz))
>> + return -EFAULT;
>> +
>> + /* Fields before the variable size union are mandatory */
>> + if (pasid_table_data.argsz < minsz)
>> + return -EINVAL;
>> +
>> + /* PASID and address granu require additional info beyond minsz
>> */
>> + if (pasid_table_data.version != PASID_TABLE_CFG_VERSION_1)
>> + return -EINVAL;
>> + if (pasid_table_data.format == IOMMU_PASID_FORMAT_SMMUV3 &&
>> + pasid_table_data.argsz <
>> + offsetofend(struct iommu_pasid_table_config,
>> vendor_data.smmuv3))
>> + return -EINVAL;
>> +
>> + /*
>> + * User might be using a newer UAPI header which has a larger
>> data
>> + * size, we shall support the existing flags within the current
>> + * size. Copy the remaining user data _after_ minsz but not more
>> + * than the current kernel supported size.
>> + */
>> + if (copy_from_user((void *)&pasid_table_data + minsz, uinfo +
>> minsz,
>> + min_t(u32, pasid_table_data.argsz,
>> sizeof(pasid_table_data)) - minsz))
>> + return -EFAULT;
>> +
>> + /* Now the argsz is validated, check the content */
>> + if (pasid_table_data.config < IOMMU_PASID_CONFIG_TRANSLATE ||
>> + pasid_table_data.config > IOMMU_PASID_CONFIG_ABORT)
>> + return -EINVAL;
>> +
>> + return domain->ops->attach_pasid_table(domain,
>> &pasid_table_data); +}
>> +EXPORT_SYMBOL_GPL(iommu_uapi_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 b95a6f8db6ff..464fcbecf841 100644
>> --- a/include/linux/iommu.h
>> +++ b/include/linux/iommu.h
>> @@ -223,6 +223,8 @@ 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
>> * @def_domain_type: device default domain type, return value:
>> * - IOMMU_DOMAIN_IDENTITY: must use an identity domain
>> * - IOMMU_DOMAIN_DMA: must use a dma domain
>> @@ -287,6 +289,9 @@ struct iommu_ops {
>> void *drvdata);
>> void (*sva_unbind)(struct iommu_sva *handle);
>> u32 (*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,
>> @@ -434,6 +439,11 @@ extern int iommu_uapi_sva_unbind_gpasid(struct
>> iommu_domain *domain, struct device *dev, void __user *udata);
>> 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 int iommu_uapi_attach_pasid_table(struct iommu_domain
>> *domain,
>> + void __user *udata);
>> +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,
>> @@ -639,6 +649,7 @@ struct iommu_sva *iommu_sva_bind_device(struct device
>> *dev, void iommu_sva_unbind_device(struct iommu_sva *handle);
>> u32 iommu_sva_get_pasid(struct iommu_sva *handle);
>>
>> +
>> #else /* CONFIG_IOMMU_API */
>>
>> struct iommu_ops {};
>> @@ -1020,6 +1031,16 @@ 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 e1d9e75f2c94..082d758dd016 100644
>> --- a/include/uapi/linux/iommu.h
>> +++ b/include/uapi/linux/iommu.h
>> @@ -338,4 +338,58 @@ struct iommu_gpasid_bind_data {
>> } vendor;
>> };
>>
>> +/**
>> + * 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
>> + * @argsz: User filled size of this data
>> + * @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)
>> + * @vendor_data.smmuv3: table information when @format is
>> + * %IOMMU_PASID_FORMAT_SMMUV3
>> + */
>> +struct iommu_pasid_table_config {
>> + __u32 argsz;
>> +#define PASID_TABLE_CFG_VERSION_1 1
>> + __u32 version;
>> +#define IOMMU_PASID_FORMAT_SMMUV3 1
>> + __u32 format;
> There will be a u32 gap here, right? perhaps another padding?
Yes you're right (as per
https://lists.cs.columbia.edu/pipermail/kvmarm/2019-January/034414.html).
I will add some padding here and add some additional padding below.

Thanks

Eric
>
>> + __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[2];
>> + union {
>> + struct iommu_pasid_smmuv3 smmuv3;
>> + } vendor_data;
>> +};
>> +
>> #endif /* _UAPI_IOMMU_H */
>
>
> Thanks,
>
> Jacob
>

Next message: Marco Elver: "Re: [PATCH] kfence: Avoid stalling work queue task without allocations"
Previous message: Alexandre Chartre: "Re: [RFC][PATCH v2 12/21] x86/pti: Use PTI stack instead of trampoline stack"
In reply to: Jacob Pan: "Re: [PATCH v13 01/15] iommu: Introduce attach/detach_pasid_table API"
Next in thread: Eric Auger: "[PATCH v13 02/15] iommu: Introduce bind/unbind_guest_msi"
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