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 B0A80EB64D9 for ; Tue, 4 Jul 2023 08:12:48 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231356AbjGDIMp (ORCPT ); Tue, 4 Jul 2023 04:12:45 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43684 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230374AbjGDIMk (ORCPT ); Tue, 4 Jul 2023 04:12:40 -0400 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 32978BD for ; Tue, 4 Jul 2023 01:11:55 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1688458314; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; 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charset=us-ascii Content-Disposition: inline In-Reply-To: <6f4c80ba-ec61-2ce8-3034-08162f0ee9fd@huawei.com> X-Scanned-By: MIMEDefang 3.1 on 10.11.54.9 Precedence: bulk List-ID: X-Mailing-List: linux-doc@vger.kernel.org On 07/04/23 at 10:18am, chenjiahao (C) wrote: > > On 2023/7/2 12:12, Baoquan He wrote: > > On 07/01/23 at 05:11pm, Chen Jiahao wrote: > > > 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 > > > Acked-by: Guo Ren > > > --- > > > arch/riscv/kernel/setup.c | 5 +++ > > > arch/riscv/mm/init.c | 84 +++++++++++++++++++++++++++++++++++---- > > > 2 files changed, 82 insertions(+), 7 deletions(-) > > > > > > diff --git a/arch/riscv/kernel/setup.c b/arch/riscv/kernel/setup.c > > > index 971fe776e2f8..376f5d49ce85 100644 > > > --- a/arch/riscv/kernel/setup.c > > > +++ b/arch/riscv/kernel/setup.c > > > @@ -178,6 +178,11 @@ 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 4b95d8999120..eeb31c2cc843 100644 > > > --- a/arch/riscv/mm/init.c > > > +++ b/arch/riscv/mm/init.c > > > @@ -1298,6 +1298,28 @@ 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 > > > * > > > @@ -1309,8 +1331,12 @@ 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(); > > > + unsigned long search_end = (unsigned long)dma32_phys_limit; > > > + char *cmdline = boot_command_line; > > > + bool fixed_base = false; > > > + bool high = false; > > > int ret = 0; > > > @@ -1326,14 +1352,36 @@ static void __init reserve_crashkernel(void) > > > return; > > > } > > > - ret = parse_crashkernel(boot_command_line, memblock_phys_mem_size(), > > > + ret = parse_crashkernel(cmdline, memblock_phys_mem_size(), > > > &crash_size, &crash_base); > > > - if (ret || !crash_size) > > > + if (ret == -ENOENT) { > > > + /* Fallback to crashkernel=X,[high,low] */ > > > + ret = parse_crashkernel_high(cmdline, 0, &crash_size, &crash_base); > > > + if (ret || !crash_size) > > > + return; > > > + > > > + /* > > > + * crashkernel=Y,low is valid only when crashkernel=X,high > > > + * is passed. > > > + */ > > > + ret = parse_crashkernel_low(cmdline, 0, &crash_low_size, &crash_base); > > > + if (ret == -ENOENT) > > > + crash_low_size = DEFAULT_CRASH_KERNEL_LOW_SIZE; > > > + else if (ret) > > > + return; > > > + > > > + search_start = (unsigned long)dma32_phys_limit; > > > + search_end = memblock_end_of_DRAM(); > > > + high = true; > > > + } else if (ret || !crash_size) { > > > + /* Invalid argument value specified */ > > > return; > > > + } > > > crash_size = PAGE_ALIGN(crash_size); > > > if (crash_base) { > > > + fixed_base = true; > > > search_start = crash_base; > > > search_end = crash_base + crash_size; > > > } > > > @@ -1346,17 +1394,39 @@ static void __init reserve_crashkernel(void) > > > * swiotlb can work on the crash kernel. > > > */ > > > crash_base = memblock_phys_alloc_range(crash_size, PMD_SIZE, > > > - search_start, > > > - min(search_end, (unsigned long) SZ_4G)); > > > + search_start, search_end); > > > if (crash_base == 0) { > > > - /* Try again without restricting region to 32bit addressible memory */ > > > + if (fixed_base) { > > > + pr_warn("crashkernel: allocating failed with given size@offset\n"); > > > + return; > > > + } > > > + > > > + if (high) { > > > + /* Fall back to lower 32G reservation */ > > > + search_start = memblock_start_of_DRAM(); > > > + search_end = (unsigned long)dma32_phys_limit; > > > + } else { > > > + /* Try again above the region of 32bit addressible memory */ > > > + search_start = (unsigned long)dma32_phys_limit; > > > + search_end = memblock_end_of_DRAM(); > > > + } > > > + > > > crash_base = memblock_phys_alloc_range(crash_size, PMD_SIZE, > > > - search_start, search_end); > > > + search_start, 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; > > How do you differentiate the case user specifies crashkernel=0M,low > > explicitly with the case that user doesn't specify crashkernel=,low, but > > only specify crsahkernel=xM,high? I saw you don't have the test case > > crashkernel=xM,high crashkernel=0M,low listed in your cover letter. > > Yes, here is indeed a point not exactly aligned with Arm64 code. > But testcases below seem to have the same result with Arm64: > > crashkernel=512M,high //high=512M, low=128M (default) > crashkernel=512M,high crashkernel=0M,low //high=512M, low=0M > crashkernel=512M,high crashkernel=256M,low //high=512M, low=256M > > > When the first allocation succeed, it will not fallback into > the if (crash_base == 0) case, the allocation result is the same > as Arm64, both for explicitly given "crashkernel=0M,low" or not. > > The problem you mentioned might occurs when the first allocation > failed. > > My logic here is when crashkernel=xM,high is specified, no matter > crashkernel=0M,low is explicitly given or not, "high" flag is set. > It will fallback to lower 4G allocation, additional lower 4G region > with "crash_low_size" will never get reserved. Ah, you are right. I was mistaken. crashkernel=xM,high crashkernel=0,low works correctly with your v6 patch. I am fine if you want to take a different code flow to implement, as long as the actual result is the same. I personally would make the code logic the same as arm64. So this patches looks good to me. > > So the results between Arm64 and riscv when crashkernel=,low is > specified or not are the same. Is there any problem with my logic, > or have I misunderstood your comment above? > > > > > > + } > > > + > > > + if ((crash_base >= dma32_phys_limit) && crash_low_size && > > > + reserve_crashkernel_low(crash_low_size)) { > > Here, additional lower memory region will not reserve when > crashkernel=xM,high is given > > > > + memblock_phys_free(crash_base, crash_size); > > > + return; > > > } > > > pr_info("crashkernel: reserved 0x%016llx - 0x%016llx (%lld MB)\n", > > > -- > > > 2.34.1 > > > > Thanks, > > Jiahao > >