From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1761789AbcLUSNw (ORCPT ); Wed, 21 Dec 2016 13:13:52 -0500 Received: from asavdk3.altibox.net ([109.247.116.14]:45097 "EHLO asavdk3.altibox.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758165AbcLUSNu (ORCPT ); Wed, 21 Dec 2016 13:13:50 -0500 Date: Wed, 21 Dec 2016 19:13:46 +0100 From: Sam Ravnborg To: Mike Kravetz 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 Subject: Re: [RFC PATCH 02/14] sparc64: add new fields to mmu context for shared context support Message-ID: <20161221181346.GC3311@ravnborg.org> 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> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.21 (2010-09-15) X-CMAE-Score: 0 X-CMAE-Analysis: v=2.2 cv=WJY9ZTkR c=1 sm=1 tr=0 a=Ij76tQDYWdb01v2+RnYW5w==:117 a=Ij76tQDYWdb01v2+RnYW5w==:17 a=kj9zAlcOel0A:10 a=nSCOcQvv3_LoQ73K1r8A:9 a=CjuIK1q_8ugA:10 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, Dec 18, 2016 at 03:45:31PM -0800, Mike Kravetz wrote: > 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. So this is the explanation for the strange changes of the constants. Add a similar explanation to the code to help the next reader. Sam