From patchwork Wed Mar 2 17:38:09 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Vijay Balakrishna X-Patchwork-Id: 12766470 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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 43FB7C433EF for ; Wed, 2 Mar 2022 17:58:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:MIME-Version:List-Subscribe:List-Help: List-Post:List-Archive:List-Unsubscribe:List-Id:Message-Id:Date:Subject:Cc:To :From:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:In-Reply-To:References: List-Owner; bh=v6n8wjnO7uuCySKbE2dV37U/iZ52CrA9eqUu6Tj2AHI=; b=Ez4j/sjV/g2WFs F/y2C9abnLQ+2t7e6QLqGK9z8y5rgqFEHFSZ3zC2k/DYTs3BnZhjsTbncAc5tr7sw0Fy7109O3CAh TyFQowjeowTagOUQU2hkKNfJ+ZMVcD6A4K1mMHo1XEdl45eim0/n9NJKcYhTL7tI3bpT3k2zXhb8C RKpbzrjJ0Eci3Z/Yimr0HP6ryj15lNykfK7RN5BQKE2gga/WM/1k48zTSLDDyFX189Nz55TKlnxYb rXWp8uHSLVQzCeacCUxuNtLSWkVWqvR3cgHe1KBowl9RauU+lJ65r743YO081DdTTFs99q4dCTeZl 42Bags6NP/9/895iopwQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1nPTDX-003gZm-Hs; Wed, 02 Mar 2022 17:56:52 +0000 Received: from linux.microsoft.com ([13.77.154.182]) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1nPSvc-003bZx-2g for linux-arm-kernel@lists.infradead.org; Wed, 02 Mar 2022 17:38:22 +0000 Received: from linuxonhyperv3.guj3yctzbm1etfxqx2vob5hsef.xx.internal.cloudapp.net (linux.microsoft.com [13.77.154.182]) by linux.microsoft.com (Postfix) with ESMTPSA id 555FA20B7188; Wed, 2 Mar 2022 09:38:18 -0800 (PST) DKIM-Filter: OpenDKIM Filter v2.11.0 linux.microsoft.com 555FA20B7188 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.microsoft.com; s=default; t=1646242698; bh=jpCEDjngC2/bz2eHcjwmhvqFaAXZYiFJDv7qBbO+CPk=; h=From:To:Cc:Subject:Date:From; b=G0fHnBHGETbVCzxilIXbUXihTO7jymeHOBP1A6zZmWHlK4RabGp9QyvFds7yKi6Pp YWufvs4tlY8soRKqVsz+LVbzCfmc4XMYtiYZsohDoY0byGG5jZ1B0LIfMbu2Q5RxuT 8SarOjn3AgxJj3JSZIz+QABCdi+RmEgHfNHtkwOA= From: Vijay Balakrishna To: Catalin Marinas , Will Deacon Cc: Nicolas Saenz Julienne , Anshuman Khandual , Mike Rapoport , Ard Biesheuvel , Pavel Tatashin , Vijay Balakrishna , linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org Subject: [PATCH v3] arm64: Do not defer reserve_crashkernel() for platforms with no DMA memory zones Date: Wed, 2 Mar 2022 09:38:09 -0800 Message-Id: <1646242689-20744-1-git-send-email-vijayb@linux.microsoft.com> X-Mailer: git-send-email 1.8.3.1 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20220302_093820_294570_D3DED98A X-CRM114-Status: GOOD ( 21.87 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org The following patches resulted in deferring crash kernel reservation to mem_init(), mainly aimed at platforms with DMA memory zones (no IOMMU), in particular Raspberry Pi 4. commit 1a8e1cef7603 ("arm64: use both ZONE_DMA and ZONE_DMA32") commit 8424ecdde7df ("arm64: mm: Set ZONE_DMA size based on devicetree's dma-ranges") commit 0a30c53573b0 ("arm64: mm: Move reserve_crashkernel() into mem_init()") commit 2687275a5843 ("arm64: Force NO_BLOCK_MAPPINGS if crashkernel reservation is required") Above changes introduced boot slowdown due to linear map creation for all the memory banks with NO_BLOCK_MAPPINGS, see discussion[1]. The proposed changes restore crash kernel reservation to earlier behavior thus avoids slow boot, particularly for platforms with IOMMU (no DMA memory zones). Tested changes to confirm no ~150ms boot slowdown on our SoC with IOMMU and 8GB memory. Also tested with ZONE_DMA and/or ZONE_DMA32 configs to confirm no regression to deferring scheme of crash kernel memory reservation. In both cases successfully collected kernel crash dump. [1] https://lore.kernel.org/all/9436d033-579b-55fa-9b00-6f4b661c2dd7@linux.microsoft.com/ Signed-off-by: Vijay Balakrishna Cc: stable@vger.kernel.org Reviewed-by: Pasha Tatashin --- Changes from v2 -> v3 --------------------- - IS_ENABLED() does not need to be an #ifdef (Mike's comment) [v2] https://lore.kernel.org/all/1645646253-16072-1-git-send-email-vijayb@linux.microsoft.com/ Changes from v1 -> v2 --------------------- - replaced '!crashk_res.end' with IS_ENABLED(ZONE_DMA/DMA32) (Nicolas's comment) - minor change to make it uniform -- replaced #if defined(..) -> #if IS_ENABLED(..) - added new comment in arch/arm64/mm/init.c to ease future maintenance (Nicolas's comment) - test performed comment moved to commit message [v1] https://lore.kernel.org/all/1645056294-6509-1-git-send-email-vijayb@linux.microsoft.com/ --- arch/arm64/mm/init.c | 36 ++++++++++++++++++++++++++++++++---- arch/arm64/mm/mmu.c | 28 +++++++++++++++++++++++++++- 2 files changed, 59 insertions(+), 5 deletions(-) diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c index db63cc885771..9e26ec80d317 100644 --- a/arch/arm64/mm/init.c +++ b/arch/arm64/mm/init.c @@ -61,8 +61,34 @@ EXPORT_SYMBOL(memstart_addr); * unless restricted on specific platforms (e.g. 30-bit on Raspberry Pi 4). * In such case, ZONE_DMA32 covers the rest of the 32-bit addressable memory, * otherwise it is empty. + * + * Memory reservation for crash kernel either done early or deferred + * depending on DMA memory zones configs (ZONE_DMA) -- + * + * In absence of ZONE_DMA configs arm64_dma_phys_limit initialized + * here instead of max_zone_phys(). This lets early reservation of + * crash kernel memory which has a dependency on arm64_dma_phys_limit. + * Reserving memory early for crash kernel allows linear creation of block + * mappings (greater than page-granularity) for all the memory bank rangs. + * In this scheme a comparatively quicker boot is observed. + * + * If ZONE_DMA configs are defined, crash kernel memory reservation + * is delayed until DMA zone memory range size initilazation performed in + * zone_sizes_init(). The defer is necessary to steer clear of DMA zone + * memory range to avoid overlap allocation. So crash kernel memory boundaries + * are not known when mapping all bank memory ranges, which otherwise means + * not possible to exclude crash kernel range from creating block mappings + * so page-granularity mappings are created for the entire memory range. + * Hence a slightly slower boot is observed. + * + * Note: Page-granularity mapppings are necessary for crash kernel memory + * range for shrinking its size via /sys/kernel/kexec_crash_size interface. */ -phys_addr_t arm64_dma_phys_limit __ro_after_init; +#if IS_ENABLED(CONFIG_ZONE_DMA) || IS_ENABLED(CONFIG_ZONE_DMA32) +phys_addr_t __ro_after_init arm64_dma_phys_limit; +#else +phys_addr_t __ro_after_init arm64_dma_phys_limit = PHYS_MASK + 1; +#endif #ifdef CONFIG_KEXEC_CORE /* @@ -153,8 +179,6 @@ static void __init zone_sizes_init(unsigned long min, unsigned long max) if (!arm64_dma_phys_limit) arm64_dma_phys_limit = dma32_phys_limit; #endif - if (!arm64_dma_phys_limit) - arm64_dma_phys_limit = PHYS_MASK + 1; max_zone_pfns[ZONE_NORMAL] = max; free_area_init(max_zone_pfns); @@ -315,6 +339,9 @@ void __init arm64_memblock_init(void) early_init_fdt_scan_reserved_mem(); + if (!IS_ENABLED(CONFIG_ZONE_DMA) && !IS_ENABLED(CONFIG_ZONE_DMA32)) + reserve_crashkernel(); + high_memory = __va(memblock_end_of_DRAM() - 1) + 1; } @@ -361,7 +388,8 @@ void __init bootmem_init(void) * request_standard_resources() depends on crashkernel's memory being * reserved, so do it here. */ - reserve_crashkernel(); + if (IS_ENABLED(CONFIG_ZONE_DMA) || IS_ENABLED(CONFIG_ZONE_DMA32)) + reserve_crashkernel(); memblock_dump_all(); } diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c index acfae9b41cc8..b32c0fb40ef7 100644 --- a/arch/arm64/mm/mmu.c +++ b/arch/arm64/mm/mmu.c @@ -517,7 +517,7 @@ static void __init map_mem(pgd_t *pgdp) */ BUILD_BUG_ON(pgd_index(direct_map_end - 1) == pgd_index(direct_map_end)); - if (can_set_direct_map() || crash_mem_map || IS_ENABLED(CONFIG_KFENCE)) + if (can_set_direct_map() || IS_ENABLED(CONFIG_KFENCE)) flags |= NO_BLOCK_MAPPINGS | NO_CONT_MAPPINGS; /* @@ -528,6 +528,15 @@ static void __init map_mem(pgd_t *pgdp) */ memblock_mark_nomap(kernel_start, kernel_end - kernel_start); + if (IS_ENABLED(CONFIG_KEXEC_CORE) && crash_mem_map) { + if (IS_ENABLED(CONFIG_ZONE_DMA) || + IS_ENABLED(CONFIG_ZONE_DMA32)) + flags |= NO_BLOCK_MAPPINGS | NO_CONT_MAPPINGS; + else if (crashk_res.end) + memblock_mark_nomap(crashk_res.start, + resource_size(&crashk_res)); + } + /* map all the memory banks */ for_each_mem_range(i, &start, &end) { if (start >= end) @@ -554,6 +563,23 @@ static void __init map_mem(pgd_t *pgdp) __map_memblock(pgdp, kernel_start, kernel_end, PAGE_KERNEL, NO_CONT_MAPPINGS); memblock_clear_nomap(kernel_start, kernel_end - kernel_start); + + /* + * Use page-level mappings here so that we can shrink the region + * in page granularity and put back unused memory to buddy system + * through /sys/kernel/kexec_crash_size interface. + */ + if (IS_ENABLED(CONFIG_KEXEC_CORE) && crash_mem_map && + !IS_ENABLED(CONFIG_ZONE_DMA) && !IS_ENABLED(CONFIG_ZONE_DMA32)) { + if (crashk_res.end) { + __map_memblock(pgdp, crashk_res.start, + crashk_res.end + 1, + PAGE_KERNEL, + NO_BLOCK_MAPPINGS | NO_CONT_MAPPINGS); + memblock_clear_nomap(crashk_res.start, + resource_size(&crashk_res)); + } + } } void mark_rodata_ro(void)