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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 79B80CA0EED for ; Wed, 20 Aug 2025 08:10:05 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id BA2578E0011; Wed, 20 Aug 2025 04:10:04 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id B790F8E0007; Wed, 20 Aug 2025 04:10:04 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id A8E338E0011; Wed, 20 Aug 2025 04:10:04 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0011.hostedemail.com [216.40.44.11]) by kanga.kvack.org (Postfix) with ESMTP id 95EAC8E0007 for ; Wed, 20 Aug 2025 04:10:04 -0400 (EDT) Received: from smtpin18.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay09.hostedemail.com (Postfix) with ESMTP id 442A58349F for ; Wed, 20 Aug 2025 08:10:04 +0000 (UTC) X-FDA: 83796412728.18.67CD7D0 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by imf21.hostedemail.com (Postfix) with ESMTP id 99D6D1C0003 for ; Wed, 20 Aug 2025 08:10:02 +0000 (UTC) Authentication-Results: imf21.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=nTvKw6Iu; spf=pass (imf21.hostedemail.com: domain of rppt@kernel.org designates 139.178.84.217 as permitted sender) smtp.mailfrom=rppt@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1755677402; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=2kU53JEnSe0Nw++617VLP4wrlRSYwLUGWBZDBSJ3y4E=; b=Vc9FabcZUDTOJ5lgW+XQIFkOv5MH58dCTqFxJuBMC7MN5K9BIXD3W5Z2RCyjLN+tltxYx2 zL9As31lPs/rM3fdRKQmIxQc6otL50aGnV5H3fGGjUxwW2pqnvli3SPAA6E4eQg5kAuV+5 GATdJnmvKcUZz6rFXnSIWAnbeO7cyGE= ARC-Authentication-Results: i=1; imf21.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=nTvKw6Iu; spf=pass (imf21.hostedemail.com: domain of rppt@kernel.org designates 139.178.84.217 as permitted sender) smtp.mailfrom=rppt@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1755677402; a=rsa-sha256; cv=none; b=E0Ny5c3xevylz57NpVbWPwyZuj8KetZHnVHM1lkxaVv+x/5ecBdoO+X1eWZBzdGlwlTeo5 BBZP4IsZ+JzsNi7Q54K/XTSrmBeC2+PClnCiI/3YCXBdHwfsgOCVq7WTFgudMPDgBIu5fO UbyyzJnwCIKZRKV6t5Ehlh0ft0jDp6E= Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by dfw.source.kernel.org (Postfix) with ESMTP id 7D8A15C5FDE; Wed, 20 Aug 2025 08:10:01 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 762BDC113D0; Wed, 20 Aug 2025 08:09:57 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1755677401; bh=ZwBIaVwfHe/T7WlfARZdRvpXDhB+IehKv0D+1cs2k44=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=nTvKw6IuGKUCM074ZO6HCTXEBhK8E5DzlI1NkU+TKjtyZQ9NfmN5Jc00uTv6/kKXa hWwxb3f4bADolcJPjWJGnr7BlVGitV9WGRgHoVDov0n0e81rrltgT7ztXG6CCOadAR A/9LHOmnMv4XoTm46Wi6wryYMO+yr1ndcmZ7Z4+cM94l/e5t+Tfq4j7t3XSGLaYVJe hdsr2Cqlnz6j/nkCAU/SqzZhmd/08f79LP5yPzmavyUjM0kJD/Dz7lE6I9jr9jrSuU BqR8XE6QJRoOvke2raPIVYoNu93YDKztyJOOABw4QkrKbpYxFS6kv6Yy/F9OwC7Q8C AdL744Lg9k08Q== Date: Wed, 20 Aug 2025 11:09:53 +0300 From: Mike Rapoport To: Evangelos Petrongonas Cc: Ard Biesheuvel , Alexander Graf , Changyuan Lyu , Andrew Morton , Baoquan He , kexec@lists.infradead.org, linux-mm@kvack.org, linux-efi@vger.kernel.org, linux-kernel@vger.kernel.org, nh-open-source@amazon.com Subject: Re: [PATCH v2 2/2] efi: Support booting with kexec handover (KHO) Message-ID: References: <9e80381d4fafc71d6e0c64d69a8b3ac9c8949865.1755643201.git.epetron@amazon.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <9e80381d4fafc71d6e0c64d69a8b3ac9c8949865.1755643201.git.epetron@amazon.de> X-Stat-Signature: n4nntmep39dbc6tjpa7m1coc9ocry3ay X-Rspam-User: X-Rspamd-Queue-Id: 99D6D1C0003 X-Rspamd-Server: rspam05 X-HE-Tag: 1755677402-329238 X-HE-Meta: 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 09WmWpMZ S8Lb9T2JeReQNUZEhOonrkZG4i8WGh0dRTw4uYdL13f2Hrob91jTUG4taP1RNiw1V657C+YV+aJrUfK5XYhbVON/TtOZc1SgN4+GKIszEJnzjcxDVtmhUo2mbSR8zBbJjV42Fn5mn2c2J5SyLdS9YzUj8dAmAb4Mn4oaqIfUNbHYK8rb9MKLoWyq38QMmKHwhiTof1C937S+VnpleTbh/fj321yatOpy24lVxEMbGH2fqu3+sSI3Zt69m5+GRHZJ664O2P+gSfv+tvLAqJ6IqRlime9MLh8lQi+CJFUtUEN2Fryt+FLHDLR6Zrg== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Tue, Aug 19, 2025 at 11:22:46PM +0000, Evangelos Petrongonas wrote: > When KHO (Kexec HandOver) is enabled, it sets up scratch memory regions > early during device tree scanning. After kexec, the new kernel > exclusively uses this region for memory allocations during boot up to > the initialization of the page allocator > > However, when booting with EFI, EFI's reserve_regions() uses > memblock_remove(0, PHYS_ADDR_MAX) to clear all memory regions before > rebuilding them from EFI data. This destroys KHO scratch regions and > their flags, thus causing a kernel panic, as there are no scratch > memory regions. > > Instead of wholesale removal, iterate through memory regions and only > remove non-KHO ones. This preserves KHO scratch regions, which are > good known memory, while still allowing EFI to rebuild its memory map. > > Signed-off-by: Evangelos Petrongonas > --- > Changes in v2: > - Replaced the for loop with for_each_mem_region > - Fixed comment indentation > - Amended commit message to specify that scratch regions > are known good regions > > drivers/firmware/efi/efi-init.c | 28 ++++++++++++++++++++++++---- > 1 file changed, 24 insertions(+), 4 deletions(-) > > diff --git a/drivers/firmware/efi/efi-init.c b/drivers/firmware/efi/efi-init.c > index a00e07b853f2..99f7eecc320f 100644 > --- a/drivers/firmware/efi/efi-init.c > +++ b/drivers/firmware/efi/efi-init.c > @@ -12,6 +12,7 @@ > #include > #include > #include > +#include > #include > #include > #include > @@ -164,12 +165,31 @@ static __init void reserve_regions(void) > pr_info("Processing EFI memory map:\n"); > > /* > - * Discard memblocks discovered so far: if there are any at this > - * point, they originate from memory nodes in the DT, and UEFI > - * uses its own memory map instead. > + * Discard memblocks discovered so far except for KHO scratch > + * regions. Most memblocks at this point originate from memory nodes > + * in the DT and UEFI uses its own memory map instead. However, if > + * KHO is enabled, scratch regions must be preserved. I'd add that KHO scratch regions are good know memory here as well. With that Acked-by: Mike Rapoport (Microsoft) > */ > memblock_dump_all(); > - memblock_remove(0, PHYS_ADDR_MAX); > + > + if (is_kho_boot()) { > + struct memblock_region *r; > + > + /* Remove all non-KHO regions */ > + for_each_mem_region(r) { > + if (!memblock_is_kho_scratch(r)) { > + memblock_remove(r->base, r->size); > + r--; > + } > + } > + } else { > + /* > + * KHO is disabled. Discard memblocks discovered so far: > + * if there are any at this point, they originate from memory > + * nodes in the DT, and UEFI uses its own memory map instead. > + */ > + memblock_remove(0, PHYS_ADDR_MAX); > + } > > for_each_efi_memory_desc(md) { > paddr = md->phys_addr; > -- > 2.47.3 -- Sincerely yours, Mike.