linux-kernel - Re: [PATCH v10 01/12] iommu: Add max_pasids field in struct iommu

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Message-ID: <a837d035-1897-99f1-03e5-0d02ab9f2b4f@intel.com>
Date:   Sun, 31 Jul 2022 19:54:13 +0800
From:   Yi Liu <yi.l.liu@...el.com>
To:     Lu Baolu <baolu.lu@...ux.intel.com>,
        Joerg Roedel <joro@...tes.org>,
        Jason Gunthorpe <jgg@...dia.com>,
        Christoph Hellwig <hch@...radead.org>,
        Kevin Tian <kevin.tian@...el.com>,
        Ashok Raj <ashok.raj@...el.com>,
        "Will Deacon" <will@...nel.org>,
        Robin Murphy <robin.murphy@....com>,
        "Jean-Philippe Brucker" <jean-philippe@...aro.com>,
        Dave Jiang <dave.jiang@...el.com>,
        "Vinod Koul" <vkoul@...nel.org>
CC:     Eric Auger <eric.auger@...hat.com>,
        Jacob jun Pan <jacob.jun.pan@...el.com>,
        Zhangfei Gao <zhangfei.gao@...aro.org>,
        Zhu Tony <tony.zhu@...el.com>, <iommu@...ts.linux.dev>,
        <linux-kernel@...r.kernel.org>,
        Jean-Philippe Brucker <jean-philippe@...aro.org>
Subject: Re: [PATCH v10 01/12] iommu: Add max_pasids field in struct
 iommu_device

On 2022/7/5 13:06, Lu Baolu wrote:
> Use this field to keep the number of supported PASIDs that an IOMMU
> hardware is able to support. This is a generic attribute of an IOMMU

a nit. it should be the max pasid value an IOMMU hardware can support
instead of number of PASIDs. right?

Reviewed-by: Yi Liu <yi.l.liu@...el.com>

> and lifting it into the per-IOMMU device structure makes it possible
> to allocate a PASID for device without calls into the IOMMU drivers.
> Any iommu driver that supports PASID related features should set this
> field before enabling them on the devices.
> 
> In the Intel IOMMU driver, intel_iommu_sm is moved to CONFIG_INTEL_IOMMU
> enclave so that the pasid_supported() helper could be used in dmar.c
> without compilation errors.
> 
> Signed-off-by: Lu Baolu <baolu.lu@...ux.intel.com>
> Reviewed-by: Jean-Philippe Brucker <jean-philippe@...aro.org>
> Reviewed-by: Kevin Tian <kevin.tian@...el.com>
> Tested-by: Zhangfei Gao <zhangfei.gao@...aro.org>
> Tested-by: Tony Zhu <tony.zhu@...el.com>
> ---
>   include/linux/intel-iommu.h                 | 3 ++-
>   include/linux/iommu.h                       | 2 ++
>   drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 1 +
>   drivers/iommu/intel/dmar.c                  | 7 +++++++
>   4 files changed, 12 insertions(+), 1 deletion(-)
> 
> diff --git a/include/linux/intel-iommu.h b/include/linux/intel-iommu.h
> index 4f29139bbfc3..e065cbe3c857 100644
> --- a/include/linux/intel-iommu.h
> +++ b/include/linux/intel-iommu.h
> @@ -479,7 +479,6 @@ enum {
>   #define VTD_FLAG_IRQ_REMAP_PRE_ENABLED	(1 << 1)
>   #define VTD_FLAG_SVM_CAPABLE		(1 << 2)
>   
> -extern int intel_iommu_sm;
>   extern spinlock_t device_domain_lock;
>   
>   #define sm_supported(iommu)	(intel_iommu_sm && ecap_smts((iommu)->ecap))
> @@ -786,6 +785,7 @@ struct context_entry *iommu_context_addr(struct intel_iommu *iommu, u8 bus,
>   extern const struct iommu_ops intel_iommu_ops;
>   
>   #ifdef CONFIG_INTEL_IOMMU
> +extern int intel_iommu_sm;
>   extern int iommu_calculate_agaw(struct intel_iommu *iommu);
>   extern int iommu_calculate_max_sagaw(struct intel_iommu *iommu);
>   extern int dmar_disabled;
> @@ -802,6 +802,7 @@ static inline int iommu_calculate_max_sagaw(struct intel_iommu *iommu)
>   }
>   #define dmar_disabled	(1)
>   #define intel_iommu_enabled (0)
> +#define intel_iommu_sm (0)
>   #endif
>   
>   static inline const char *decode_prq_descriptor(char *str, size_t size,
> diff --git a/include/linux/iommu.h b/include/linux/iommu.h
> index 5e1afe169549..03fbb1b71536 100644
> --- a/include/linux/iommu.h
> +++ b/include/linux/iommu.h
> @@ -318,12 +318,14 @@ struct iommu_domain_ops {
>    * @list: Used by the iommu-core to keep a list of registered iommus
>    * @ops: iommu-ops for talking to this iommu
>    * @dev: struct device for sysfs handling
> + * @max_pasids: number of supported PASIDs
>    */
>   struct iommu_device {
>   	struct list_head list;
>   	const struct iommu_ops *ops;
>   	struct fwnode_handle *fwnode;
>   	struct device *dev;
> +	u32 max_pasids;
>   };
>   
>   /**
> diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
> index 88817a3376ef..ae8ec8df47c1 100644
> --- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
> +++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
> @@ -3546,6 +3546,7 @@ static int arm_smmu_device_hw_probe(struct arm_smmu_device *smmu)
>   	/* SID/SSID sizes */
>   	smmu->ssid_bits = FIELD_GET(IDR1_SSIDSIZE, reg);
>   	smmu->sid_bits = FIELD_GET(IDR1_SIDSIZE, reg);
> +	smmu->iommu.max_pasids = 1UL << smmu->ssid_bits;
>   
>   	/*
>   	 * If the SMMU supports fewer bits than would fill a single L2 stream
> diff --git a/drivers/iommu/intel/dmar.c b/drivers/iommu/intel/dmar.c
> index 592c1e1a5d4b..6c338888061a 100644
> --- a/drivers/iommu/intel/dmar.c
> +++ b/drivers/iommu/intel/dmar.c
> @@ -1123,6 +1123,13 @@ static int alloc_iommu(struct dmar_drhd_unit *drhd)
>   
>   	raw_spin_lock_init(&iommu->register_lock);
>   
> +	/*
> +	 * A value of N in PSS field of eCap register indicates hardware
> +	 * supports PASID field of N+1 bits.
> +	 */
> +	if (pasid_supported(iommu))
> +		iommu->iommu.max_pasids = 2UL << ecap_pss(iommu->ecap);
> +
>   	/*
>   	 * This is only for hotplug; at boot time intel_iommu_enabled won't
>   	 * be set yet. When intel_iommu_init() runs, it registers the units

-- 
Regards,
Yi Liu