From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752563AbcLRXqx (ORCPT ); Sun, 18 Dec 2016 18:46:53 -0500 Received: from userp1040.oracle.com ([156.151.31.81]:26027 "EHLO userp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750914AbcLRXqv (ORCPT ); Sun, 18 Dec 2016 18:46:51 -0500 Subject: Re: [RFC PATCH 02/14] sparc64: add new fields to mmu context for shared context support To: Sam Ravnborg References: <1481913337-9331-1-git-send-email-mike.kravetz@oracle.com> <1481913337-9331-3-git-send-email-mike.kravetz@oracle.com> <20161217073813.GB23567@ravnborg.org> Cc: sparclinux@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, "David S . Miller" , Bob Picco , Nitin Gupta , Vijay Kumar , Julian Calaby , Adam Buchbinder , "Kirill A . Shutemov" , Michal Hocko , Andrew Morton From: Mike Kravetz Message-ID: Date: Sun, 18 Dec 2016 15:45:31 -0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.5.1 MIME-Version: 1.0 In-Reply-To: <20161217073813.GB23567@ravnborg.org> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit X-Source-IP: aserv0021.oracle.com [141.146.126.233] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 12/16/2016 11:38 PM, Sam Ravnborg wrote: > Hi Mike > >> diff --git a/arch/sparc/include/asm/mmu_context_64.h b/arch/sparc/include/asm/mmu_context_64.h >> index b84be67..d031799 100644 >> --- a/arch/sparc/include/asm/mmu_context_64.h >> +++ b/arch/sparc/include/asm/mmu_context_64.h >> @@ -35,15 +35,15 @@ void __tsb_context_switch(unsigned long pgd_pa, >> static inline void tsb_context_switch(struct mm_struct *mm) >> { >> __tsb_context_switch(__pa(mm->pgd), >> - &mm->context.tsb_block[0], >> + &mm->context.tsb_block[MM_TSB_BASE], >> #if defined(CONFIG_HUGETLB_PAGE) || defined(CONFIG_TRANSPARENT_HUGEPAGE) >> - (mm->context.tsb_block[1].tsb ? >> - &mm->context.tsb_block[1] : >> + (mm->context.tsb_block[MM_TSB_HUGE].tsb ? >> + &mm->context.tsb_block[MM_TSB_HUGE] : >> NULL) >> #else >> NULL >> #endif >> - , __pa(&mm->context.tsb_descr[0])); >> + , __pa(&mm->context.tsb_descr[MM_TSB_BASE])); >> } >> > This is a nice cleanup that has nothing to do with your series. > Could you submit this as a separate patch so we can get it applied. > > This is the only place left where the array index for tsb_block > and tsb_descr uses hardcoded values. And it would be good to get > rid of these. Sure, I will submit a separate cleanup patch for this. However, do note that in my series if CONFIG_SHARED_MMU_CTX is defined, then MM_TSB_HUGE_SHARED is index 0, instead of MM_TSB_BASE being 0 in the case where CONFIG_SHARED_MMU_CTX is not defined. This may seem 'strange' and the obvious question would be 'why not put CONFIG_SHARED_MMU_CTX at the end of the existing array (index 2)?'. The reason is that tsb_descr array can not have any 'holes' when passed to the hypervisor. Since there will always be a MM_TSB_BASE tsb, with MM_TSB_HUGE_SHARED before and MM_TSB_HUGE after MM_TSB_BASE, few tricks are necessary to ensure no holes are in the array passed to the hypervisor. -- Mike Kravetz