From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754799AbdERGIP (ORCPT ); Thu, 18 May 2017 02:08:15 -0400 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:36287 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1752354AbdERGIO (ORCPT ); Thu, 18 May 2017 02:08:14 -0400 Subject: Re: [PATCH v3 2/2] powerpc/mm/hugetlb: Add support for 1G huge pages To: Michael Ellerman , akpm@linux-foundation.org, Anshuman Khandual Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org References: <1494995292-4443-1-git-send-email-aneesh.kumar@linux.vnet.ibm.com> <1494995292-4443-2-git-send-email-aneesh.kumar@linux.vnet.ibm.com> <87fug2loze.fsf@concordia.ellerman.id.au> From: "Aneesh Kumar K.V" Date: Thu, 18 May 2017 11:37:59 +0530 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.1.1 MIME-Version: 1.0 In-Reply-To: <87fug2loze.fsf@concordia.ellerman.id.au> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 x-cbid: 17051806-0040-0000-0000-000003415D79 X-IBM-SpamModules-Scores: X-IBM-SpamModules-Versions: BY=3.00007080; HX=3.00000241; KW=3.00000007; PH=3.00000004; SC=3.00000212; SDB=6.00862087; UDB=6.00427648; IPR=6.00641745; BA=6.00005356; NDR=6.00000001; ZLA=6.00000005; ZF=6.00000009; ZB=6.00000000; ZP=6.00000000; ZH=6.00000000; ZU=6.00000002; MB=3.00015498; XFM=3.00000015; UTC=2017-05-18 06:08:11 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 17051806-0041-0000-0000-000007358CAA Message-Id: <852b601c-a044-0445-e97d-d17d76ec1154@linux.vnet.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:,, definitions=2017-05-18_01:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 suspectscore=0 malwarescore=0 phishscore=0 adultscore=0 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1703280000 definitions=main-1705180042 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thursday 18 May 2017 10:51 AM, Michael Ellerman wrote: > "Aneesh Kumar K.V" writes: > >> POWER9 supports hugepages of size 2M and 1G in radix MMU mode. This patch >> enables the usage of 1G page size for hugetlbfs. This also update the helper >> such we can do 1G page allocation at runtime. >> >> We still don't enable 1G page size on DD1 version. This is to avoid doing >> workaround mentioned in commit: 6d3a0379ebdc8 (powerpc/mm: Add >> radix__tlb_flush_pte_p9_dd1() >> >> Signed-off-by: Aneesh Kumar K.V >> --- >> arch/powerpc/include/asm/book3s/64/hugetlb.h | 10 ++++++++++ >> arch/powerpc/mm/hugetlbpage.c | 7 +++++-- >> arch/powerpc/platforms/Kconfig.cputype | 1 + >> 3 files changed, 16 insertions(+), 2 deletions(-) > > I think this patch is OK, but it's very confusing because it doesn't > mention that it's only talking about *generic* gigantic page support. What you mean by generic gigantic page ? what is supported here is the gigantic page with size 1G alone ? > > We have existing support for gigantic pages on powerpc, on several > platforms. This patch appears to break that, but I think doesn't in > practice? > What is broken ? > So can you make it a bit clearer in the commit message, and the code, > that this is only about enabling the generic gigantic page support, and > is unrelated to the arch-specific gigantic page support. > > cheers > >> diff --git a/arch/powerpc/include/asm/book3s/64/hugetlb.h b/arch/powerpc/include/asm/book3s/64/hugetlb.h >> index 6666cd366596..5c28bd6f2ae1 100644 >> --- a/arch/powerpc/include/asm/book3s/64/hugetlb.h >> +++ b/arch/powerpc/include/asm/book3s/64/hugetlb.h >> @@ -50,4 +50,14 @@ static inline pte_t arch_make_huge_pte(pte_t entry, struct vm_area_struct *vma, >> else >> return entry; >> } >> + >> +#ifdef CONFIG_ARCH_HAS_GIGANTIC_PAGE >> +static inline bool gigantic_page_supported(void) >> +{ >> + if (radix_enabled()) >> + return true; >> + return false; >> +} >> +#endif >> + >> #endif >> diff --git a/arch/powerpc/mm/hugetlbpage.c b/arch/powerpc/mm/hugetlbpage.c >> index a4f33de4008e..80f6d2ed551a 100644 >> --- a/arch/powerpc/mm/hugetlbpage.c >> +++ b/arch/powerpc/mm/hugetlbpage.c >> @@ -763,8 +763,11 @@ static int __init add_huge_page_size(unsigned long long size) >> * Hash: 16M and 16G >> */ >> if (radix_enabled()) { >> - if (mmu_psize != MMU_PAGE_2M) >> - return -EINVAL; >> + if (mmu_psize != MMU_PAGE_2M) { >> + if (cpu_has_feature(CPU_FTR_POWER9_DD1) || >> + (mmu_psize != MMU_PAGE_1G)) >> + return -EINVAL; >> + } >> } else { >> if (mmu_psize != MMU_PAGE_16M && mmu_psize != MMU_PAGE_16G) >> return -EINVAL; >> diff --git a/arch/powerpc/platforms/Kconfig.cputype b/arch/powerpc/platforms/Kconfig.cputype >> index 684e886eaae4..b76ef6637016 100644 >> --- a/arch/powerpc/platforms/Kconfig.cputype >> +++ b/arch/powerpc/platforms/Kconfig.cputype >> @@ -344,6 +344,7 @@ config PPC_STD_MMU_64 >> config PPC_RADIX_MMU >> bool "Radix MMU Support" >> depends on PPC_BOOK3S_64 >> + select ARCH_HAS_GIGANTIC_PAGE if (MEMORY_ISOLATION && COMPACTION) || CMA >> default y >> help >> Enable support for the Power ISA 3.0 Radix style MMU. Currently this >> -- >> 2.7.4 >