linux-kernel - Re: [PATCH v4 3/4] iommufd: Add IOMMU_GET_HW

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Message-ID: <ZL65z0i8d42Try7a@nvidia.com>
Date:   Mon, 24 Jul 2023 14:50:07 -0300
From:   Jason Gunthorpe <jgg@...dia.com>
To:     Yi Liu <yi.l.liu@...el.com>
Cc:     joro@...tes.org, alex.williamson@...hat.com, kevin.tian@...el.com,
        robin.murphy@....com, baolu.lu@...ux.intel.com, cohuck@...hat.com,
        eric.auger@...hat.com, nicolinc@...dia.com, kvm@...r.kernel.org,
        mjrosato@...ux.ibm.com, chao.p.peng@...ux.intel.com,
        yi.y.sun@...ux.intel.com, peterx@...hat.com, jasowang@...hat.com,
        shameerali.kolothum.thodi@...wei.com, lulu@...hat.com,
        suravee.suthikulpanit@....com, iommu@...ts.linux.dev,
        linux-kernel@...r.kernel.org, linux-kselftest@...r.kernel.org,
        zhenzhong.duan@...el.com
Subject: Re: [PATCH v4 3/4] iommufd: Add IOMMU_GET_HW_INFO

On Mon, Jul 24, 2023 at 03:59:35AM -0700, Yi Liu wrote:
> diff --git a/drivers/iommu/iommufd/main.c b/drivers/iommu/iommufd/main.c
> index 94c498b8fdf6..bd3efc1d8509 100644
> --- a/drivers/iommu/iommufd/main.c
> +++ b/drivers/iommu/iommufd/main.c
> @@ -17,6 +17,7 @@
>  #include <linux/bug.h>
>  #include <uapi/linux/iommufd.h>
>  #include <linux/iommufd.h>
> +#include "../iommu-priv.h"
>  
>  #include "io_pagetable.h"
>  #include "iommufd_private.h"
> @@ -177,6 +178,78 @@ static int iommufd_destroy(struct iommufd_ucmd *ucmd)
>  	return 0;
>  }
>  
> +static int iommufd_zero_fill_user(u64 ptr, int bytes)

(void __user * ptr, size_t bytes)

> +{
> +	int index = 0;
> +
> +	for (; index < bytes; index++) {
> +		if (put_user(0, (uint8_t __user *)u64_to_user_ptr(ptr + index)))
> +			return -EFAULT;
> +	}
> +	return 0;
> +}
> +
> +static int iommufd_get_hw_info(struct iommufd_ucmd *ucmd)
> +{
> +	struct iommu_hw_info *cmd = ucmd->cmd;
> +	unsigned int length = 0, data_len;
> +	struct iommufd_device *idev;
> +	const struct iommu_ops *ops;
> +	void *data = NULL;
> +	int rc = 0;
> +
> +	if (cmd->flags || cmd->__reserved || !cmd->data_len)
> +		return -EOPNOTSUPP;
> +
> +	idev = iommufd_get_device(ucmd, cmd->dev_id);
> +	if (IS_ERR(idev))
> +		return PTR_ERR(idev);
> +
> +	ops = dev_iommu_ops(idev->dev);
> +	if (!ops->hw_info)
> +		goto done;
> +
> +	/* driver has hw_info callback should have a unique hw_info_type */
> +	if (WARN_ON_ONCE(ops->hw_info_type == IOMMU_HW_INFO_TYPE_NONE)) {
> +		pr_warn_ratelimited("iommu driver set an invalid type\n");

Don't really need both a WARN and pr_warn(), just keep the WARN_ON

Jason