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 AEE0021765B; Mon, 1 Dec 2025 09:18:45 +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=1764580725; cv=none; b=Ci7UNPBGRfX3ZmpUDMkEth3XW0SIMXDFe7rq0grdr8rMrPLbkVcQjxZTX0ampw1ySmAYC1CYJwCjjTNCtchDUZEf2M0tqg7tu8uMkffA/mdpr7NFLO64uby1f/vxP7lg9qZfrJQTa9iU+k/MtQUHLgmHSlR5crdLftJ/O3G8lcY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1764580725; c=relaxed/simple; bh=qWp6QKEfPfpxLUmqgtn55SeILlnnhx0o/0HpFCZjylY=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=FFVGtRb8ptsT4QcO6frkvFPxiyhzbvUJX948+CRIGc48d5v0yiE7dySwT9LwVgRLnpxNYnx8V6/YIA0O6qYP3AT66DFA9BntLNIKbdDjPRR5WStxCaVGRQF9EEWhsMLLazb8yv4bCIj/arfDqGQiLmW3VLa046CavI+uPqt3+Wg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=LCLEM5LO; 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="LCLEM5LO" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 91652C4CEF1; Mon, 1 Dec 2025 09:18:40 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1764580725; bh=qWp6QKEfPfpxLUmqgtn55SeILlnnhx0o/0HpFCZjylY=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=LCLEM5LOdK4VTSpDstiX63Jcdt88wt0TLg17IBcCaa43907suA29aPg/LYKHG0q9y 70BPoZAyi/0h0BWg9phe/Wx4nxITfIF+JH8jTzpmijHYnh7kZRMkXc5QmS+XrTY1Fp SERtNsiEKqfUMDjpm90ZWmnJaja9csucNVSgviYi4L5UEipYBzxCU9GL1oeOmIRmbb eK9j+iC7NmO3a8Ru205q3gCmqa1prsC9bd31ydK9UBwGwxr9tt+BnIYE6tnhRHi4Ik 97YkhkH06XH62JmMxo2htRq3qaWecptFQrE+Fdxi630V3F0kSCokiDvVYJlNhutqEM EyuylCUql/yDA== Message-ID: <47927c25-a317-488a-823f-ac0588f4eee4@kernel.org> Date: Mon, 1 Dec 2025 10:18:37 +0100 Precedence: bulk X-Mailing-List: linux-efi@vger.kernel.org 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> From: "David Hildenbrand (Red Hat)" Content-Language: en-US In-Reply-To: <20251128113411.GAaSmIs0kSWGhCYkaA@fat_crate.local> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 11/28/25 12:34, Borislav Petkov wrote: > On Fri, Nov 28, 2025 at 10:30:15AM +0100, David Hildenbrand (Red Hat) wrote: >> kexecing the same kernel is typically used for kdump purposes. >> >> kexecing different kernels is used for all sorts of things (live-upgrade, >> grub-emu come to mind). It's quite common to kexec different kernels, or >> maybe I misunderstood the question here? > > And my question is: since when do we enforce no-ABI-changes between kernels so > that we can kexec any kernel into any kernel? > > By that logic I should be able to kexec 5.x into 6.x. I'll bet some money that > it won't work. I *think* ordinary kexec would likely work, as I recall that it doesn't need a lot of that special kexec ABI sauce like unaccepted memory uses. Within confidential VMs (kexec ...) I am pretty sure that it's a different discussion. > > So unless it is written down somewhere, I think we should probably talk first > what we want to support and why... > > Makes sense? Makes sense to me, especially for confidential VMs where we pass such kernel-managed data from the old to the new kernel. -- Cheers David