linux-kernel - Re: [PATCH v5 11/23] driver core: add per device iommu param

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Date:   Mon, 14 May 2018 13:27:13 +0800
From:   Lu Baolu <baolu.lu@...ux.intel.com>
To:     Jacob Pan <jacob.jun.pan@...ux.intel.com>,
        iommu@...ts.linux-foundation.org,
        LKML <linux-kernel@...r.kernel.org>,
        Joerg Roedel <joro@...tes.org>,
        David Woodhouse <dwmw2@...radead.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Alex Williamson <alex.williamson@...hat.com>,
        Jean-Philippe Brucker <jean-philippe.brucker@....com>
Cc:     Rafael Wysocki <rafael.j.wysocki@...el.com>,
        "Liu, Yi L" <yi.l.liu@...el.com>,
        "Tian, Kevin" <kevin.tian@...el.com>,
        Raj Ashok <ashok.raj@...el.com>,
        Jean Delvare <khali@...ux-fr.org>,
        Christoph Hellwig <hch@...radead.org>
Subject: Re: [PATCH v5 11/23] driver core: add per device iommu param

Hi,

On 05/12/2018 04:54 AM, Jacob Pan wrote:
> DMA faults can be detected by IOMMU at device level. Adding a pointer
> to struct device allows IOMMU subsystem to report relevant faults
> back to the device driver for further handling.
> For direct assigned device (or user space drivers), guest OS holds
> responsibility to handle and respond per device IOMMU fault.
> Therefore we need fault reporting mechanism to propagate faults beyond
> IOMMU subsystem.
>
> There are two other IOMMU data pointers under struct device today, here
> we introduce iommu_param as a parent pointer such that all device IOMMU
> data can be consolidated here. The idea was suggested here by Greg KH
> and Joerg. The name iommu_param is chosen here since iommu_data has been used.

This doesn't match what you've done in the patch. Maybe you
forgot to cleanup? :-)

The idea is to create a parent pointer under device struct and
move previous iommu_group and iommu_fwspec together with
the iommu fault related data into it.

Best regards,
Lu Baolu

>
> Suggested-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
> Reviewed-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
> Signed-off-by: Jacob Pan <jacob.jun.pan@...ux.intel.com>
> Link: https://lkml.org/lkml/2017/10/6/81
> ---
>  include/linux/device.h | 3 +++
>  1 file changed, 3 insertions(+)
>
> diff --git a/include/linux/device.h b/include/linux/device.h
> index 4779569..c1b1796 100644
> --- a/include/linux/device.h
> +++ b/include/linux/device.h
> @@ -41,6 +41,7 @@ struct iommu_ops;
>  struct iommu_group;
>  struct iommu_fwspec;
>  struct dev_pin_info;
> +struct iommu_param;
>  
>  struct bus_attribute {
>  	struct attribute	attr;
> @@ -899,6 +900,7 @@ struct dev_links_info {
>   * 		device (i.e. the bus driver that discovered the device).
>   * @iommu_group: IOMMU group the device belongs to.
>   * @iommu_fwspec: IOMMU-specific properties supplied by firmware.
> + * @iommu_param: Per device generic IOMMU runtime data
>   *
>   * @offline_disabled: If set, the device is permanently online.
>   * @offline:	Set after successful invocation of bus type's .offline().
> @@ -988,6 +990,7 @@ struct device {
>  	void	(*release)(struct device *dev);
>  	struct iommu_group	*iommu_group;
>  	struct iommu_fwspec	*iommu_fwspec;
> +	struct iommu_param	*iommu_param;
>  
>  	bool			offline_disabled:1;
>  	bool			offline:1;