linux-kernel - Re: [PATCH v10 02/12] iommu: Add max_pasids field in struct dev

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Message-ID: <17aefaaa-ef95-016e-e028-f8091829a508@intel.com>
Date:   Sun, 31 Jul 2022 19:55:15 +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>
Subject: Re: [PATCH v10 02/12] iommu: Add max_pasids field in struct dev_iommu

On 2022/7/5 13:07, Lu Baolu wrote:
> Use this field to save the number of PASIDs that a device is able to
> consume. It is a generic attribute of a device and lifting it into the
> per-device dev_iommu struct could help to avoid the boilerplate code
> in various IOMMU drivers.
> 
> Signed-off-by: Lu Baolu <baolu.lu@...ux.intel.com>
> 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/iommu.h |  2 ++
>   drivers/iommu/iommu.c | 20 ++++++++++++++++++++
>   2 files changed, 22 insertions(+)

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

> diff --git a/include/linux/iommu.h b/include/linux/iommu.h
> index 03fbb1b71536..418a1914a041 100644
> --- a/include/linux/iommu.h
> +++ b/include/linux/iommu.h
> @@ -364,6 +364,7 @@ struct iommu_fault_param {
>    * @fwspec:	 IOMMU fwspec data
>    * @iommu_dev:	 IOMMU device this device is linked to
>    * @priv:	 IOMMU Driver private data
> + * @max_pasids:  number of PASIDs this device can consume
>    *
>    * TODO: migrate other per device data pointers under iommu_dev_data, e.g.
>    *	struct iommu_group	*iommu_group;
> @@ -375,6 +376,7 @@ struct dev_iommu {
>   	struct iommu_fwspec		*fwspec;
>   	struct iommu_device		*iommu_dev;
>   	void				*priv;
> +	u32				max_pasids;
>   };
>   
>   int iommu_device_register(struct iommu_device *iommu,
> diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
> index cdc86c39954e..0cb0750f61e8 100644
> --- a/drivers/iommu/iommu.c
> +++ b/drivers/iommu/iommu.c
> @@ -20,6 +20,7 @@
>   #include <linux/idr.h>
>   #include <linux/err.h>
>   #include <linux/pci.h>
> +#include <linux/pci-ats.h>
>   #include <linux/bitops.h>
>   #include <linux/property.h>
>   #include <linux/fsl/mc.h>
> @@ -218,6 +219,24 @@ static void dev_iommu_free(struct device *dev)
>   	kfree(param);
>   }
>   
> +static u32 dev_iommu_get_max_pasids(struct device *dev)
> +{
> +	u32 max_pasids = 0, bits = 0;
> +	int ret;
> +
> +	if (dev_is_pci(dev)) {
> +		ret = pci_max_pasids(to_pci_dev(dev));
> +		if (ret > 0)
> +			max_pasids = ret;
> +	} else {
> +		ret = device_property_read_u32(dev, "pasid-num-bits", &bits);
> +		if (!ret)
> +			max_pasids = 1UL << bits;
> +	}
> +
> +	return min_t(u32, max_pasids, dev->iommu->iommu_dev->max_pasids);
> +}
> +
>   static int __iommu_probe_device(struct device *dev, struct list_head *group_list)
>   {
>   	const struct iommu_ops *ops = dev->bus->iommu_ops;
> @@ -243,6 +262,7 @@ static int __iommu_probe_device(struct device *dev, struct list_head *group_list
>   	}
>   
>   	dev->iommu->iommu_dev = iommu_dev;
> +	dev->iommu->max_pasids = dev_iommu_get_max_pasids(dev);
>   
>   	group = iommu_group_get_for_dev(dev);
>   	if (IS_ERR(group)) {

-- 
Regards,
Yi Liu