netdev - Re: [PATCH 05/18] iommu/fsl_pamu: remove support for multiple windows

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Message-ID: <20210330122234.GE5908@willie-the-truck>
Date:   Tue, 30 Mar 2021 13:22:34 +0100
From:   Will Deacon <will@...nel.org>
To:     Christoph Hellwig <hch@....de>
Cc:     Joerg Roedel <joro@...tes.org>, Li Yang <leoyang.li@....com>,
        Michael Ellerman <mpe@...erman.id.au>,
        David Woodhouse <dwmw2@...radead.org>,
        Lu Baolu <baolu.lu@...ux.intel.com>,
        linuxppc-dev@...ts.ozlabs.org, linux-arm-msm@...r.kernel.org,
        dri-devel@...ts.freedesktop.org, freedreno@...ts.freedesktop.org,
        iommu@...ts.linux-foundation.org,
        linux-arm-kernel@...ts.infradead.org, kvm@...r.kernel.org,
        virtualization@...ts.linux-foundation.org, netdev@...r.kernel.org
Subject: Re: [PATCH 05/18] iommu/fsl_pamu: remove support for multiple windows

On Tue, Mar 16, 2021 at 04:38:11PM +0100, Christoph Hellwig wrote:
> The only domains allocated forces use of a single window.  Remove all
> the code related to multiple window support, as well as the need for
> qman_portal to force a single window.
> 
> Remove the now unused DOMAIN_ATTR_WINDOWS iommu_attr.
> 
> Signed-off-by: Christoph Hellwig <hch@....de>
> Acked-by: Li Yang <leoyang.li@....com>
> ---
>  drivers/iommu/fsl_pamu.c            | 264 +-------------------------
>  drivers/iommu/fsl_pamu.h            |  10 +-
>  drivers/iommu/fsl_pamu_domain.c     | 275 +++++-----------------------
>  drivers/iommu/fsl_pamu_domain.h     |  12 +-
>  drivers/soc/fsl/qbman/qman_portal.c |   7 -
>  include/linux/iommu.h               |   1 -
>  6 files changed, 59 insertions(+), 510 deletions(-)

[...]

> +	set_bf(ppaace->impl_attr, PAACE_IA_ATM, PAACE_ATM_WINDOW_XLATE);
> +	ppaace->twbah = rpn >> 20;
> +	set_bf(ppaace->win_bitfields, PAACE_WIN_TWBAL, rpn);
> +	set_bf(ppaace->addr_bitfields, PAACE_AF_AP, prot);
> +	set_bf(ppaace->impl_attr, PAACE_IA_WCE, 0);
> +	set_bf(ppaace->addr_bitfields, PPAACE_AF_MW, 0);
>  	mb();

(I wonder what on Earth that mb() is doing...)

> diff --git a/drivers/iommu/fsl_pamu_domain.h b/drivers/iommu/fsl_pamu_domain.h
> index 53d359d66fe577..b9236fb5a8f82e 100644
> --- a/drivers/iommu/fsl_pamu_domain.h
> +++ b/drivers/iommu/fsl_pamu_domain.h
> @@ -17,23 +17,13 @@ struct dma_window {
>  };
>  
>  struct fsl_dma_domain {
> -	/*
> -	 * Number of windows assocaited with this domain.
> -	 * During domain initialization, it is set to the
> -	 * the maximum number of subwindows allowed for a LIODN.
> -	 * Minimum value for this is 1 indicating a single PAMU
> -	 * window, without any sub windows. Value can be set/
> -	 * queried by set_attr/get_attr API for DOMAIN_ATTR_WINDOWS.
> -	 * Value can only be set once the geometry has been configured.
> -	 */
> -	u32				win_cnt;
>  	/*
>  	 * win_arr contains information of the configured
>  	 * windows for a domain. This is allocated only
>  	 * when the number of windows for the domain are
>  	 * set.
>  	 */

The last part of this comment is now stale ^^

> -	struct dma_window		*win_arr;
> +	struct dma_window		win_arr[1];
>  	/* list of devices associated with the domain */
>  	struct list_head		devices;
>  	/* dma_domain states:

Acked-by: Will Deacon <will@...nel.org>

Will