[PATCH 1/2] [Zesty] UBUNTU: SAUCE: powerpc/mm/radix: Don't do page walk cache flush when doing full mm flush

[Colin Ian King]

On 10/04/17 14:23, Breno Leitao wrote:
> From: "Aneesh Kumar K.V" <aneesh.kumar at linux.vnet.ibm.com>
> 
> BugLink: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1681429
> 
> For fullmm tlb flush, we do a flush with RIC_FLUSH_ALL which will invalidate all
> related caches (radix__tlb_flush()). Hence the pwc flush is not needed.
> 
> Signed-off-by: Aneesh Kumar K.V <aneesh.kumar at linux.vnet.ibm.com>
> Acked-by: Anton Blanchard <anton at samba.org>
> Signed-off-by: Breno Leitao <breno.leitao at gmail.com>
> ---
>  arch/powerpc/mm/tlb-radix.c | 12 ++++++++++++
>  1 file changed, 12 insertions(+)
> 
> diff --git a/arch/powerpc/mm/tlb-radix.c b/arch/powerpc/mm/tlb-radix.c
> index 952713d6cf04..74f17e3c7cbe 100644
> --- a/arch/powerpc/mm/tlb-radix.c
> +++ b/arch/powerpc/mm/tlb-radix.c
> @@ -129,6 +129,12 @@ void radix__local_flush_tlb_pwc(struct mmu_gather *tlb, unsigned long addr)
>  {
>  	unsigned long pid;
>  	struct mm_struct *mm = tlb->mm;
> +	/*
> +	 * If we are doing a full mm flush, we will do a tlb flush
> +	 * with RIC_FLUSH_ALL later.
> +	 */
> +	if (tlb->fullmm)
> +		return;
>  
>  	preempt_disable();
>  
> @@ -195,6 +201,12 @@ void radix__flush_tlb_pwc(struct mmu_gather *tlb, unsigned long addr)
>  	unsigned long pid;
>  	struct mm_struct *mm = tlb->mm;
>  
> +	/*
> +	 * If we are doing a full mm flush, we will do a tlb flush
> +	 * with RIC_FLUSH_ALL later.
> +	 */
> +	if (tlb->fullmm)
> +		return;
>  	preempt_disable();
>  
>  	pid = mm->context.id;
> 

Patches 1 and 2 are clear optimizations and are arch-specific. Both
appear OK to me.

Acked-by: Colin Ian King <colin.king at canonical.com>