linux-kernel - Re: [PATCH 3/4] powerpc/pseries/iommu: Move window-removing part of remove_ddw into remove_dma

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Message-ID: <51201582-efe5-85df-7e65-a998e91ab63f@ozlabs.ru>
Date:   Mon, 22 Jun 2020 20:02:39 +1000
From:   Alexey Kardashevskiy <aik@...abs.ru>
To:     Leonardo Bras <leobras.c@...il.com>,
        Michael Ellerman <mpe@...erman.id.au>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>,
        Thiago Jung Bauermann <bauerman@...ux.ibm.com>,
        Ram Pai <linuxram@...ibm.com>
Cc:     linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 3/4] powerpc/pseries/iommu: Move window-removing part of
 remove_ddw into remove_dma_window



On 19/06/2020 15:06, Leonardo Bras wrote:
> Move the window-removing part of remove_ddw into a new function
> (remove_dma_window), so it can be used to remove other DMA windows.
> 
> It's useful for removing DMA windows that don't create DIRECT64_PROPNAME
> property, like the default DMA window from the device, which uses
> "ibm,dma-window".
> 
> Signed-off-by: Leonardo Bras <leobras.c@...il.com>
> ---
>  arch/powerpc/platforms/pseries/iommu.c | 53 +++++++++++++++-----------
>  1 file changed, 31 insertions(+), 22 deletions(-)
> 
> diff --git a/arch/powerpc/platforms/pseries/iommu.c b/arch/powerpc/platforms/pseries/iommu.c
> index 5e1fbc176a37..de633f6ae093 100644
> --- a/arch/powerpc/platforms/pseries/iommu.c
> +++ b/arch/powerpc/platforms/pseries/iommu.c
> @@ -767,25 +767,14 @@ static int __init disable_ddw_setup(char *str)
>  
>  early_param("disable_ddw", disable_ddw_setup);
>  
> -static void remove_ddw(struct device_node *np, bool remove_prop)
> +static void remove_dma_window(struct device_node *pdn, u32 *ddw_avail,

You do not need the entire ddw_avail here, pass just the token you need.

Also, despite this particular file, the "pdn" name is usually used for
struct pci_dn (not device_node), let's keep it that way.


> +			      struct property *win)
>  {
>  	struct dynamic_dma_window_prop *dwp;
> -	struct property *win64;
> -	u32 ddw_avail[3];
>  	u64 liobn;
> -	int ret = 0;
> -
> -	ret = of_property_read_u32_array(np, "ibm,ddw-applicable",
> -					 &ddw_avail[0], 3);
> -
> -	win64 = of_find_property(np, DIRECT64_PROPNAME, NULL);
> -	if (!win64)
> -		return;
> -
> -	if (ret || win64->length < sizeof(*dwp))
> -		goto delprop;
> +	int ret;
>  
> -	dwp = win64->value;
> +	dwp = win->value;
>  	liobn = (u64)be32_to_cpu(dwp->liobn);
>  
>  	/* clear the whole window, note the arg is in kernel pages */
> @@ -793,24 +782,44 @@ static void remove_ddw(struct device_node *np, bool remove_prop)
>  		1ULL << (be32_to_cpu(dwp->window_shift) - PAGE_SHIFT), dwp);
>  	if (ret)
>  		pr_warn("%pOF failed to clear tces in window.\n",
> -			np);
> +			pdn);
>  	else
>  		pr_debug("%pOF successfully cleared tces in window.\n",
> -			 np);
> +			 pdn);
>  
>  	ret = rtas_call(ddw_avail[2], 1, 1, NULL, liobn);
>  	if (ret)
>  		pr_warn("%pOF: failed to remove direct window: rtas returned "
>  			"%d to ibm,remove-pe-dma-window(%x) %llx\n",
> -			np, ret, ddw_avail[2], liobn);
> +			pdn, ret, ddw_avail[2], liobn);
>  	else
>  		pr_debug("%pOF: successfully removed direct window: rtas returned "
>  			"%d to ibm,remove-pe-dma-window(%x) %llx\n",
> -			np, ret, ddw_avail[2], liobn);
> +			pdn, ret, ddw_avail[2], liobn);
> +}
> +
> +static void remove_ddw(struct device_node *np, bool remove_prop)
> +{
> +	struct property *win;
> +	u32 ddw_avail[3];
> +	int ret = 0;
> +
> +	ret = of_property_read_u32_array(np, "ibm,ddw-applicable",
> +					 &ddw_avail[0], 3);
> +	if (ret)
> +		return;
> +
> +	win = of_find_property(np, DIRECT64_PROPNAME, NULL);
> +	if (!win)
> +		return;
> +
> +	if (win->length >= sizeof(struct dynamic_dma_window_prop))


Any good reason not to make it "=="? Is there something optional or we
expect extension (which may not grow from the end but may add cells in
between). Thanks,


> +		remove_dma_window(np, ddw_avail, win);
> +
> +	if (!remove_prop)
> +		return;
>  
> -delprop:
> -	if (remove_prop)
> -		ret = of_remove_property(np, win64);
> +	ret = of_remove_property(np, win);
>  	if (ret)
>  		pr_warn("%pOF: failed to remove direct window property: %d\n",
>  			np, ret);
> 

-- 
Alexey