From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 63C9E211A09; Mon, 1 Dec 2025 18:32:45 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1764613965; cv=none; b=EVd1N8Hl6s62Szvtx727xNJ50KXzv5pXE2nRFQH+3Okf4YVOR3HQaa4tVeyg6y8LmyCyV+afaZss/QEaXZ3NBAOM9gT4JUbcFmG9R+XaUmxPeYBZ7FBRGS+hNAfVZ9qOT6yM3OF4ocz08bNsZRZjNun0OvDPmWlaAB4wYF0qt9Q= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1764613965; c=relaxed/simple; bh=2IfzNXSfzN92nTYZTzGsXr1fBjpjDfpWrXwW0YZPKmg=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=RrIUN8VQD8ebyaVAeTlOS5vOPfU2nlmJby82CYC1e0ehacBzZl0lA04PzPrEdg8etHDur0Mc5rnTWfVm4sB4aL5LxodkTjy49KgpkvIhslqRQ/YXB+ob5Xr/ymaLEXccetwf05ps1wRcdYkGdRaWV8zcWvhgeg8ZnV+vaQPvVMk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=bdEAf+gF; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="bdEAf+gF" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 95955C4CEF1; Mon, 1 Dec 2025 18:32:40 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1764613964; bh=2IfzNXSfzN92nTYZTzGsXr1fBjpjDfpWrXwW0YZPKmg=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=bdEAf+gFID+PrIxA1/+WE4DYDfDJBXtzv1cVw+nJIpuZeM4V7UDOI6jNrBiUD+JiU Do/ziqGJ20sAbyjbWPOYm7gpCJsOOaoO0oOY3Q/c/n2u2g3F3WkpuCK+tGySIpJ7/a 4bHtVR3xPkyARb5tRlMwGubNri7MqXAER1PYHxOrlxfT978nc0ysn8YYAyDp0R2UJa ylvgL0h8z4rxROQi+p/OmfAf/EI5TUidCbLe8wG4JDv0gCn34+s5WqaQzw9lbi9t+0 YB+7uvR+JnDYAJVwUa/iKVshebyq9AUbnu27D3pI2QqNfHXVsrtP4EF6cRnIBRZw1w svVlqTs6UAx3g== Message-ID: <052d7f47-edb6-4978-bc9a-c7eae469720f@kernel.org> Date: Mon, 1 Dec 2025 19:32:38 +0100 Precedence: bulk X-Mailing-List: linux-coco@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [RFC PATCH 2/4] mm: Add support for unaccepted memory hotplug To: Borislav Petkov Cc: Kiryl Shutsemau , "Pratik R. Sampat" , linux-mm@kvack.org, linux-coco@lists.linux.dev, linux-efi@vger.kernel.org, x86@kernel.org, linux-kernel@vger.kernel.org, tglx@linutronix.de, mingo@redhat.com, dave.hansen@linux.intel.com, ardb@kernel.org, akpm@linux-foundation.org, osalvador@suse.de, thomas.lendacky@amd.com, michael.roth@amd.com References: <20251125175753.1428857-1-prsampat@amd.com> <20251125175753.1428857-3-prsampat@amd.com> <66ylzwknm4ftd6utn3nqr63jmhl2ccvcdvyi5fechfnvmfxivu@37pckhjixayh> <20251126223127.GIaSd_v7juUkaW4RTA@fat_crate.local> <20251127181233.GBaSiUkaLzwANS_6WT@fat_crate.local> <20251128113411.GAaSmIs0kSWGhCYkaA@fat_crate.local> <47927c25-a317-488a-823f-ac0588f4eee4@kernel.org> <20251201111201.GAaS14AX18qeHN20xf@fat_crate.local> From: "David Hildenbrand (Red Hat)" Content-Language: en-US In-Reply-To: <20251201111201.GAaS14AX18qeHN20xf@fat_crate.local> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 12/1/25 12:12, Borislav Petkov wrote: > On Mon, Dec 01, 2025 at 10:18:37AM +0100, David Hildenbrand (Red Hat) wrote: >> Makes sense to me, especially for confidential VMs where we pass such >> kernel-managed data from the old to the new kernel. > > It shouldn't matter, right? > > I think the question is whether the kernel should agree to the software > contract (/eyeroll) to keep the kernel ABI compatible wrt kexec. > > And I don't think we have agreed to that AFAIK. I think we are in agreement: from what I recall, this software contract used to be rather simple and stable. Looking into the details, I guess it's all about $ grep "define LINUX_EFI_" include/linux/efi.h #define LINUX_EFI_CRASH_GUID EFI_GUID(0xcfc8fc79, 0xbe2e, 0x4ddc, 0x97, 0xf0, 0x9f, 0x98, 0xbf, 0xe2, 0x98, 0xa0) #define LINUX_EFI_SCREEN_INFO_TABLE_GUID EFI_GUID(0xe03fc20a, 0x85dc, 0x406e, 0xb9, 0x0e, 0x4a, 0xb5, 0x02, 0x37, 0x1d, 0x95) #define LINUX_EFI_ARM_CPU_STATE_TABLE_GUID EFI_GUID(0xef79e4aa, 0x3c3d, 0x4989, 0xb9, 0x02, 0x07, 0xa9, 0x43, 0xe5, 0x50, 0xd2) #define LINUX_EFI_LOADER_ENTRY_GUID EFI_GUID(0x4a67b082, 0x0a4c, 0x41cf, 0xb6, 0xc7, 0x44, 0x0b, 0x29, 0xbb, 0x8c, 0x4f) #define LINUX_EFI_RANDOM_SEED_TABLE_GUID EFI_GUID(0x1ce1e5bc, 0x7ceb, 0x42f2, 0x81, 0xe5, 0x8a, 0xad, 0xf1, 0x80, 0xf5, 0x7b) #define LINUX_EFI_TPM_EVENT_LOG_GUID EFI_GUID(0xb7799cb0, 0xeca2, 0x4943, 0x96, 0x67, 0x1f, 0xae, 0x07, 0xb7, 0x47, 0xfa) #define LINUX_EFI_MEMRESERVE_TABLE_GUID EFI_GUID(0x888eb0c6, 0x8ede, 0x4ff5, 0xa8, 0xf0, 0x9a, 0xee, 0x5c, 0xb9, 0x77, 0xc2) #define LINUX_EFI_INITRD_MEDIA_GUID EFI_GUID(0x5568e427, 0x68fc, 0x4f3d, 0xac, 0x74, 0xca, 0x55, 0x52, 0x31, 0xcc, 0x68) #define LINUX_EFI_MOK_VARIABLE_TABLE_GUID EFI_GUID(0xc451ed2b, 0x9694, 0x45d3, 0xba, 0xba, 0xed, 0x9f, 0x89, 0x88, 0xa3, 0x89) #define LINUX_EFI_COCO_SECRET_AREA_GUID EFI_GUID(0xadf956ad, 0xe98c, 0x484c, 0xae, 0x11, 0xb5, 0x1c, 0x7d, 0x33, 0x64, 0x47) #define LINUX_EFI_BOOT_MEMMAP_GUID EFI_GUID(0x800f683f, 0xd08b, 0x423a, 0xa2, 0x93, 0x96, 0x5c, 0x3c, 0x6f, 0xe2, 0xb4) #define LINUX_EFI_UNACCEPTED_MEM_TABLE_GUID EFI_GUID(0xd5d1de3c, 0x105c, 0x44f9, 0x9e, 0xa9, 0xbc, 0xef, 0x98, 0x12, 0x00, 0x31) #define LINUX_EFI_LOADED_IMAGE_FIXED_GUID EFI_GUID(0xf5a37b6d, 0x3344, 0x42a5, 0xb6, 0xbb, 0x97, 0x86, 0x48, 0xc1, 0x89, 0x0a) Likely the format of these section stayed unchanged over the years. -- Cheers David