linux-kernel - Re: [PATCH V2] powerpc/pseries/svm: Drop unused align argument in alloc_shared

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Date:   Tue, 16 Jun 2020 10:24:10 +0200
From:   Laurent Dufour <ldufour@...ux.ibm.com>
To:     Satheesh Rajendran <sathnaga@...ux.vnet.ibm.com>,
        linuxppc-dev@...ts.ozlabs.org
Cc:     linux-kernel@...r.kernel.org,
        Thiago Jung Bauermann <bauerman@...ux.ibm.com>,
        Ram Pai <linuxram@...ibm.com>,
        Sukadev Bhattiprolu <sukadev@...ux.vnet.ibm.com>,
        Michael Ellerman <mpe@...erman.id.au>
Subject: Re: [PATCH V2] powerpc/pseries/svm: Drop unused align argument in
 alloc_shared_lppaca() function

Le 12/06/2020 à 16:29, Satheesh Rajendran a écrit :
> Argument "align" in alloc_shared_lppaca() was unused inside the
> function. Let's drop it and update code comment for page alignment.
> 
> Cc: linux-kernel@...r.kernel.org
> Cc: Thiago Jung Bauermann <bauerman@...ux.ibm.com>
> Cc: Ram Pai <linuxram@...ibm.com>
> Cc: Sukadev Bhattiprolu <sukadev@...ux.vnet.ibm.com>
> Cc: Laurent Dufour <ldufour@...ux.ibm.com>
> Cc: Michael Ellerman <mpe@...erman.id.au>
> Reviewed-by: Thiago Jung Bauermann <bauerman@...ux.ibm.com>

Reviewed-by: Laurent Dufour <ldufour@...ux.ibm.com>

> Signed-off-by: Satheesh Rajendran <sathnaga@...ux.vnet.ibm.com>
> ---
> 
> V2:
> Added reviewed by Thiago.
> Dropped align argument as per Michael suggest.
> Modified commit msg.
> 
> V1: http://patchwork.ozlabs.org/project/linuxppc-dev/patch/20200609113909.17236-1-sathnaga@linux.vnet.ibm.com/
> ---
>   arch/powerpc/kernel/paca.c | 12 +++++++++---
>   1 file changed, 9 insertions(+), 3 deletions(-)
> 
> diff --git a/arch/powerpc/kernel/paca.c b/arch/powerpc/kernel/paca.c
> index 8d96169c597e..a174d64d9b4d 100644
> --- a/arch/powerpc/kernel/paca.c
> +++ b/arch/powerpc/kernel/paca.c
> @@ -57,8 +57,8 @@ static void *__init alloc_paca_data(unsigned long size, unsigned long align,
>   
>   #define LPPACA_SIZE 0x400
>   
> -static void *__init alloc_shared_lppaca(unsigned long size, unsigned long align,
> -					unsigned long limit, int cpu)
> +static void *__init alloc_shared_lppaca(unsigned long size, unsigned long limit,
> +					int cpu)
>   {
>   	size_t shared_lppaca_total_size = PAGE_ALIGN(nr_cpu_ids * LPPACA_SIZE);
>   	static unsigned long shared_lppaca_size;
> @@ -68,6 +68,12 @@ static void *__init alloc_shared_lppaca(unsigned long size, unsigned long align,
>   	if (!shared_lppaca) {
>   		memblock_set_bottom_up(true);
>   
> +		/* See Documentation/powerpc/ultravisor.rst for mode details
> +		 *
> +		 * UV/HV data share is in PAGE granularity, In order to
> +		 * minimize the number of pages shared and maximize the
> +		 * use of a page, let's use page align.
> +		 */
>   		shared_lppaca =
>   			memblock_alloc_try_nid(shared_lppaca_total_size,
>   					       PAGE_SIZE, MEMBLOCK_LOW_LIMIT,
> @@ -122,7 +128,7 @@ static struct lppaca * __init new_lppaca(int cpu, unsigned long limit)
>   		return NULL;
>   
>   	if (is_secure_guest())
> -		lp = alloc_shared_lppaca(LPPACA_SIZE, 0x400, limit, cpu);
> +		lp = alloc_shared_lppaca(LPPACA_SIZE, limit, cpu);
>   	else
>   		lp = alloc_paca_data(LPPACA_SIZE, 0x400, limit, cpu);
>   
>