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 AA958351C30; Tue, 19 May 2026 11:11:50 +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=1779189110; cv=none; b=Ux8nbI/iNiVL8uSesMUlR4c0NtA5/h3grcayptzO3NG1QTzPnHLMmoxyRVSvxRIhaK4LZvEDXeVDd8dkRW0/DLLC1ki/UZc28uGzTpZx6K9cXy3PxvR4hghSFfZ8+q/Of2etzaNt3uMFP+seoMNqQWyOCAgfv8N0HSvwJSEK3hA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779189110; c=relaxed/simple; bh=yho1oY7rUwGUBK6N3ReIa8imE1mEl4Xep1Oe5MlRzKg=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=u5BfenvvUZQz4mWK+fVHpt6LDz1lXwAXpjofb4glXMn9mhV/iJGsCUCG71ckRje5ie4v/AAd9Mgk9UI/7gZ0j+8eaB8r5VFSA+tnl/69YpIkl5b8h/G1ose4Vg0pGRfbdT+HaNZmBYU5IpUfV7vs7RO79tYVIrMjndTRLg/LYMw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=ZIA+Mx51; 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="ZIA+Mx51" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 1EB23C2BCB3; Tue, 19 May 2026 11:11:45 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1779189110; bh=yho1oY7rUwGUBK6N3ReIa8imE1mEl4Xep1Oe5MlRzKg=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=ZIA+Mx511B2Utvn8fqrlK5XwSL8vqCOwjgfy/t0ERyQP2GgjcHBvxaBcaz/+rZ18J 0CrpDV+n1qekubCKlZWpnJmE82yshPea4TnybMcHaE+QYIMwkljLEFlxIVTqMbq5dx p+bEZdKaRfP4JF3HO5II7EeaBytLydOBoJQe+Zs35ZNoMdXWzyeknmt3ZRISzIfQr2 HPDKmcPWvg8kQiiPLq+VWUmTdcdgiXAsO6V2VXBl84LLkcAqZwz6qN9ws8wvRkwzMl aeqM9OuflbaGHxAGN6ds3muEW0LgDxQKUUbyaYUZxPKXW/BMGOIMin/d5MRp7xsP3r BRSjZhUoU2/xA== Date: Tue, 19 May 2026 12:11:42 +0100 From: Will Deacon To: David Woodhouse Cc: Paolo Bonzini , Marc Zyngier , Jonathan Corbet , Shuah Khan , kvm , Linux Doc Mailing List , "Kernel Mailing List, Linux" , Sean Christopherson , Jim Mattson , Oliver Upton , Joey Gouly , Suzuki K Poulose , Zenghui Yu , Catalin Marinas , Raghavendra Rao Ananta , Eric Auger , Kees Cook , Arnd Bergmann , Nathan Chancellor , linux-arm-kernel , kvmarm@lists.linux.dev, linux-kselftest Subject: Re: [PATCH] Documentation: KVM: Document guest-visible compatibility expectations Message-ID: References: <6856b269d2af706eae397e0cf9c1231f89d9a932.camel@infradead.org> <6afc4b95-3c15-4d71-877d-19b84e91ce05@redhat.com> <57bc082f4824d6114d3156744c25986effc29aca.camel@infradead.org> <86h5obya2r.wl-maz@kernel.org> <48b06e5655d56ff6eda30e563b34894fa0eb2f07.camel@infradead.org> <3f9d731c3d26b0367600f1069e6425099bc34eac.camel@infradead.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <3f9d731c3d26b0367600f1069e6425099bc34eac.camel@infradead.org> On Tue, May 19, 2026 at 11:41:26AM +0100, David Woodhouse wrote: > On Wed, 2026-05-13 at 18:24 +0200, Paolo Bonzini wrote: > > > > > See commit https://git.kernel.org/torvalds/c/49a1a2c70a7f which adds a > > > new guest-visible feature in revision 3, but allowed userspace to > > > restore the old behaviour by setting it to revision 2. All my patch > > > above does, is make it possible to set it to revision 1 as > > > well. Because https://git.kernel.org/torvalds/c/d53c2c29ae0d previously > > > changed the behaviour and bumped the default to 2 *without* allowing > > > userspace to restore the prior behaviour, and we've been carrying a > > > *revert* of that patch. > > > > > > Why would we *not* accept such a patch? > > > > Agreed. Even ignoring your revert, there's no reason why any upgrade > > past 49a1a2c70a7f has to be from after d53c2c29ae0d. > > So where do we go from here? > > I assume you'll be taking this Documentation patch via the KVM tree? > > But what about the actual fix at > https://lore.kernel.org/all/20260511113558.3325004-2-dwmw2@infradead.org/ > > This is a simple and unintrusive bug fix to make KVM/arm64 follow the > "common sense" requirement that the doc patch codifies, apparently > being rejected with the rather bizarre claim that KVM has no *need* to > maintain guest-visible compatibility across host kernel changes. > > So... what next? Is one of the other KVM/arm64 maintainers going to > speak up? Paolo would you consider taking the fixes through your tree > directly? > > Does Arm not actually *care* whether AArch64 is considered a stable and > mature platform for KVM hosting? Hey, come on. Marc cares more about this stuff than anybody else on the planet. He's been single-handedly maintaining the tree for the past couple of releases while Oliver was out and he's on the end of a _lot_ of patches. I'm only cc'd on a fraction of the KVM/arm64 changes and it's bedlam. Will