linux-kernel - Re: [PATCH 1/3] powerpc/mm: Initialize the HPTE encoding values

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Date:   Thu, 12 Sep 2019 19:07:12 +0530
From:   "Aneesh Kumar K.V" <aneesh.kumar@...ux.ibm.com>
To:     Laurent Dufour <ldufour@...ux.ibm.com>, mpe@...erman.id.au,
        benh@...nel.crashing.org, paulus@...ba.org, npiggin@...il.com
Cc:     linuxppc-dev@...ts.ozlabs.org, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/3] powerpc/mm: Initialize the HPTE encoding values

On 8/30/19 5:37 PM, Laurent Dufour wrote:
> Before reading the HPTE encoding values we initialize all of them to -1 (an
> invalid value) to later being able to detect the initialized ones.
> 
> Signed-off-by: Laurent Dufour <ldufour@...ux.ibm.com>
> ---
>   arch/powerpc/mm/book3s64/hash_utils.c | 8 ++++++--
>   1 file changed, 6 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/powerpc/mm/book3s64/hash_utils.c b/arch/powerpc/mm/book3s64/hash_utils.c
> index c3bfef08dcf8..2039bc315459 100644
> --- a/arch/powerpc/mm/book3s64/hash_utils.c
> +++ b/arch/powerpc/mm/book3s64/hash_utils.c
> @@ -408,7 +408,7 @@ static int __init htab_dt_scan_page_sizes(unsigned long node,
>   {
>   	const char *type = of_get_flat_dt_prop(node, "device_type", NULL);
>   	const __be32 *prop;
> -	int size = 0;
> +	int size = 0, idx, base_idx;
>   
>   	/* We are scanning "cpu" nodes only */
>   	if (type == NULL || strcmp(type, "cpu") != 0)
> @@ -418,6 +418,11 @@ static int __init htab_dt_scan_page_sizes(unsigned long node,
>   	if (!prop)
>   		return 0;
>   
> +	/* Set all the penc values to invalid */
> +	for (base_idx = 0; base_idx < MMU_PAGE_COUNT; base_idx++)
> +		for (idx = 0; idx < MMU_PAGE_COUNT; idx++)
> +			mmu_psize_defs[base_idx].penc[idx] = -1;
> +
>   	pr_info("Page sizes from device-tree:\n");
>   	size /= 4;
>   	cur_cpu_spec->mmu_features &= ~(MMU_FTR_16M_PAGE);
> @@ -426,7 +431,6 @@ static int __init htab_dt_scan_page_sizes(unsigned long node,
>   		unsigned int slbenc = be32_to_cpu(prop[1]);
>   		unsigned int lpnum = be32_to_cpu(prop[2]);
>   		struct mmu_psize_def *def;
> -		int idx, base_idx;
>   
>   		size -= 3; prop += 3;
>   		base_idx = get_idx_from_shift(base_shift);
> 

We already do this in mmu_psize_set_default_penc() ?

-aneesh