linux-kernel - Re: [PATCH v5 04/12] iommu/vt-d: Add 256-bit invalidation descriptor support

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Message-ID: <20181203134856.lui4us4ejm4d5avz@8bytes.org>
Date:   Mon, 3 Dec 2018 14:48:56 +0100
From:   Joerg Roedel <joro@...tes.org>
To:     Lu Baolu <baolu.lu@...ux.intel.com>
Cc:     David Woodhouse <dwmw2@...radead.org>, ashok.raj@...el.com,
        sanjay.k.kumar@...el.com, jacob.jun.pan@...el.com,
        kevin.tian@...el.com, yi.l.liu@...el.com, yi.y.sun@...el.com,
        peterx@...hat.com,
        Jean-Philippe Brucker <jean-philippe.brucker@....com>,
        iommu@...ts.linux-foundation.org, linux-kernel@...r.kernel.org,
        Jacob Pan <jacob.jun.pan@...ux.intel.com>
Subject: Re: [PATCH v5 04/12] iommu/vt-d: Add 256-bit invalidation descriptor
 support

On Wed, Nov 28, 2018 at 11:54:41AM +0800, Lu Baolu wrote:
> -
> -	desc_page = alloc_pages_node(iommu->node, GFP_ATOMIC | __GFP_ZERO, 0);
> +	/*
> +	 * Need two pages to accommodate 256 descriptors of 256 bits each
> +	 * if the remapping hardware supports scalable mode translation.
> +	 */
> +	desc_page = alloc_pages_node(iommu->node, GFP_ATOMIC | __GFP_ZERO,
> +				     !!ecap_smts(iommu->ecap));


Same here, does the allocation really need GFP_ATOMIC?

>  struct q_inval {
>  	raw_spinlock_t  q_lock;
> -	struct qi_desc  *desc;          /* invalidation queue */
> +	void		*desc;          /* invalidation queue */
>  	int             *desc_status;   /* desc status */
>  	int             free_head;      /* first free entry */
>  	int             free_tail;      /* last free entry */

Why do you switch the pointer to void* ?


	Joerg