From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 76FFFC761AF for ; Thu, 30 Mar 2023 13:40:48 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231951AbjC3Nkr (ORCPT ); Thu, 30 Mar 2023 09:40:47 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51834 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231922AbjC3Nkp (ORCPT ); Thu, 30 Mar 2023 09:40:45 -0400 Received: from szxga02-in.huawei.com (szxga02-in.huawei.com [45.249.212.188]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1FD281FFC; Thu, 30 Mar 2023 06:40:38 -0700 (PDT) Received: from dggpemm500016.china.huawei.com (unknown [172.30.72.54]) by szxga02-in.huawei.com (SkyGuard) with ESMTP id 4PnPbZ2rqwzSqBR; Thu, 30 Mar 2023 21:36:58 +0800 (CST) Received: from [10.67.108.26] (10.67.108.26) by dggpemm500016.china.huawei.com (7.185.36.25) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2507.21; Thu, 30 Mar 2023 21:40:35 +0800 Message-ID: Date: Thu, 30 Mar 2023 21:40:35 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:102.0) Gecko/20100101 Thunderbird/102.9.0 Subject: Re: [PATCH -next v2 1/2] riscv: kdump: Implement crashkernel=X,[high,low] Content-Language: en-US To: Baoquan He CC: , , , , , , , , , , , , , , References: <20230328115150.2700016-1-chenjiahao16@huawei.com> <20230328115150.2700016-2-chenjiahao16@huawei.com> From: "chenjiahao (C)" In-Reply-To: Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 7bit X-Originating-IP: [10.67.108.26] X-ClientProxiedBy: dggems706-chm.china.huawei.com (10.3.19.183) To dggpemm500016.china.huawei.com (7.185.36.25) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2023/3/29 19:19, Baoquan He wrote: > On 03/28/23 at 07:51pm, Chen Jiahao wrote: Thanks for reviewing. >> On riscv, the current crash kernel allocation logic is trying to >> allocate within 32bit addressible memory region by default, if >> failed, try to allocate without 4G restriction. >> >> In need of saving DMA zone memory while allocating a relatively large >> crash kernel region, allocating the reserved memory top down in >> high memory, without overlapping the DMA zone, is a mature solution. >> Here introduce the parameter option crashkernel=X,[high,low]. >> >> One can reserve the crash kernel from high memory above DMA zone range >> by explicitly passing "crashkernel=X,high"; or reserve a memory range >> below 4G with "crashkernel=X,low". >> >> Signed-off-by: Chen Jiahao >> --- >> arch/riscv/kernel/setup.c | 5 ++++ >> arch/riscv/mm/init.c | 63 ++++++++++++++++++++++++++++++++++++--- >> 2 files changed, 64 insertions(+), 4 deletions(-) >> >> diff --git a/arch/riscv/kernel/setup.c b/arch/riscv/kernel/setup.c >> index 5d3184cbf518..ea84e5047c23 100644 >> --- a/arch/riscv/kernel/setup.c >> +++ b/arch/riscv/kernel/setup.c >> @@ -176,6 +176,11 @@ static void __init init_resources(void) >> if (ret < 0) >> goto error; >> } >> + if (crashk_low_res.start != crashk_low_res.end) { >> + ret = add_resource(&iomem_resource, &crashk_low_res); >> + if (ret < 0) >> + goto error; >> + } >> #endif >> >> #ifdef CONFIG_CRASH_DUMP >> diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c >> index 478d6763a01a..b7708cc467fa 100644 >> --- a/arch/riscv/mm/init.c >> +++ b/arch/riscv/mm/init.c >> @@ -1152,6 +1152,28 @@ static inline void setup_vm_final(void) >> } >> #endif /* CONFIG_MMU */ >> >> +/* Reserve 128M low memory by default for swiotlb buffer */ >> +#define DEFAULT_CRASH_KERNEL_LOW_SIZE (128UL << 20) >> + >> +static int __init reserve_crashkernel_low(unsigned long long low_size) >> +{ >> + unsigned long long low_base; >> + >> + low_base = memblock_phys_alloc_range(low_size, PMD_SIZE, 0, dma32_phys_limit); >> + if (!low_base) { >> + pr_err("cannot allocate crashkernel low memory (size:0x%llx).\n", low_size); >> + return -ENOMEM; >> + } >> + >> + pr_info("crashkernel low memory reserved: 0x%016llx - 0x%016llx (%lld MB)\n", >> + low_base, low_base + low_size, low_size >> 20); >> + >> + crashk_low_res.start = low_base; >> + crashk_low_res.end = low_base + low_size - 1; >> + >> + return 0; >> +} >> + >> /* >> * reserve_crashkernel() - reserves memory for crash kernel >> * >> @@ -1163,6 +1185,7 @@ static void __init reserve_crashkernel(void) >> { >> unsigned long long crash_base = 0; >> unsigned long long crash_size = 0; >> + unsigned long long crash_low_size = 0; >> unsigned long search_start = memblock_start_of_DRAM(); >> unsigned long search_end = memblock_end_of_DRAM(); >> >> @@ -1182,8 +1205,30 @@ static void __init reserve_crashkernel(void) >> >> ret = parse_crashkernel(boot_command_line, memblock_phys_mem_size(), >> &crash_size, &crash_base); >> - if (ret || !crash_size) >> + if (ret == -ENOENT) { >> + /* >> + * crashkernel=X,[high,low] can be specified or not, but >> + * invalid value is not allowed. >> + */ >> + ret = parse_crashkernel_high(boot_command_line, 0, &crash_size, &crash_base); > I would add a local variable to assign boot_command_line to it just like > arm64 does. Then these lines could be shorter. > > char *cmdline = boot_command_line; Agreed, I will clean this up later in next version. >> + if (ret || !crash_size) >> + return; >> + >> + /* >> + * crashkernel=Y,low is valid only when crashkernel=X,high >> + * is passed and high memory is reserved successful. >> + */ >> + ret = parse_crashkernel_low(boot_command_line, 0, &crash_low_size, &crash_base); >> + if (ret == -ENOENT) >> + crash_low_size = DEFAULT_CRASH_KERNEL_LOW_SIZE; >> + else if (ret) >> + return; >> + >> + search_start = dma32_phys_limit; >> + } else if (ret || !crash_size) { >> + /* Invalid argument value specified */ >> return; >> + } >> >> crash_size = PAGE_ALIGN(crash_size); >> >> @@ -1201,16 +1246,26 @@ static void __init reserve_crashkernel(void) >> */ >> crash_base = memblock_phys_alloc_range(crash_size, PMD_SIZE, >> search_start, >> - min(search_end, (unsigned long) SZ_4G)); >> + min(search_end, (unsigned long)dma32_phys_limit)); >> if (crash_base == 0) { > The above conditional check isn't right. If crashkernel=size@offset > specified, the reservation failure won't trigger retry. This seems to be > originally introduced by old commit, while this need be fixed firstly. Just a little curious about the rule to cope with this specific case. If "crashkernel=size@offset" was passed but reserve failed, should try again to allocate in high memory, regardless the specified size@offset, or just throw a warning and return? Since I noticed the current logic here on Arm64 is to check if !fixed_base first before retrying. Or have I missed anything else? >> - /* Try again without restricting region to 32bit addressible memory */ >> + /* Try again above the region of 32bit addressible memory */ >> crash_base = memblock_phys_alloc_range(crash_size, PMD_SIZE, >> - search_start, search_end); >> + max(search_start, (unsigned long)dma32_phys_limit), >> + search_end); >> if (crash_base == 0) { >> pr_warn("crashkernel: couldn't allocate %lldKB\n", >> crash_size >> 10); >> return; >> } >> + >> + if (!crash_low_size) >> + crash_low_size = DEFAULT_CRASH_KERNEL_LOW_SIZE; >> + } >> + >> + if ((crash_base > dma32_phys_limit - crash_low_size) && >> + crash_low_size && reserve_crashkernel_low(crash_low_size)) { >> + memblock_phys_free(crash_base, crash_size); >> + return; >> } >> >> pr_info("crashkernel: reserved 0x%016llx - 0x%016llx (%lld MB)\n", >> -- >> 2.31.1 >> BR, Jiahao