From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 A0BCA432BE7; Fri, 10 Jul 2026 15:37:08 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783697835; cv=none; b=DsPSITtkj4ti+aOpO46bcsal+mE9Rq5YtWwvDyXzjQku4P4uooOyjqY0uSQHo92YpbjZzfU6mpWPpmWiPgWVEMgTmrnFeFPYtzb6NH5xoFXm2U9vToxZWhufWIMMjoMSnKIhQy1eabGqyFQc2IB6hs0UoiwOjcT9Ef5n0a40F+A= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783697835; c=relaxed/simple; bh=EmQ7+h+prGU3DRftvDRQKfPZOGXZR1nWcv4czpwxaQo=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=KAEO5PTQsLYU0dDxxEmo7yc0K9M/WSTUYPnhHI9/zJproUHu7FBm1PyaHcjRqy+Ao/S1znqt564X85KwfWumxwC+5R1+INJsVBEX3p2FmTfPoXD2eGdb+TnMRr45eymlzO4sme34nHHmOrElwkiTPEmnyMzw2BSLWUvOny7hJkc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=ivf4m5vv; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="ivf4m5vv" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 2BB691F000E9; Fri, 10 Jul 2026 15:37:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1783697826; bh=uHMOBRio+zwcgdJ4h+lXgOEUz1Hkz0fl7vBNq5yda0Y=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=ivf4m5vv7igvZZhV83qetmzKvie37bG2aC+7ICtpeZaZQHxZM6w+qKGFxJd4VTjVW Gh5IkcoRr8GUXHR5gZGUN0DyejNdEZ2Y9qQ3qJXaNgHi0hED6hVrDGW5cGiK2SEp7q xf8/7nbfjchfNWxVyoB/JhwRcvxw3m3N+kdq54zdF5eqJM4aOalwJJKPHcgYNNif5S 0Vu/ZICwNB8F0qXM9dU1STcPfaZatvJQ8tx4DtpJ8BiKU9BhZpL0zpAhO/3jGi96pp mlIrgIPahHd8PDoWFhv9ABagje/WnwznFWvt1TeG33k5z+u/jUNZ95qnDJQ3nVc1sT AtwKqRgzpX0Qg== Message-ID: <62ccb0f7-a619-41b8-944e-11ae2d0ce70c@kernel.org> Date: Fri, 10 Jul 2026 17:37:01 +0200 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] KVM: SEV: drop FOLL_LONGTERM for encrypted region registration To: Lorenzo Stoakes Cc: "Gupta, Pankaj" , seanjc@google.com, pbonzini@redhat.com, tglx@kernel.org, mingo@redhat.com, dave.hansen@linux.intel.com, bp@alien8.de, x86@kernel.org, thomas.lendacky@amd.com, hpa@zytor.com, yangge1116@126.com, kvm@vger.kernel.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org References: <20260701144543.39582-1-pankaj.gupta@amd.com> <1cc159b9-5f94-4524-8e03-efe91601ccfc@kernel.org> <46f19bd8-0d43-4b0e-a8ab-0ef9d3b8bd1a@kernel.org> <2bd89e95-9c15-4a3a-916d-0d71a92d8b02@amd.com> <27ebe8f0-78b6-402a-a2e7-4e807251d20a@kernel.org> <58c4326d-b10d-42dc-af5d-3a5ff16c7e3e@amd.com> From: "David Hildenbrand (Arm)" Content-Language: en-US Autocrypt: addr=david@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 7bit On 7/10/26 15:05, Lorenzo Stoakes wrote: > On Fri, Jul 10, 2026 at 02:57:55PM +0200, David Hildenbrand (Arm) wrote: >> On 7/9/26 17:44, Lorenzo Stoakes wrote: >>> >>> OK as long as that's made clear in the patch, commit message, comments etc. :) >>> >>> >>> Ack yeah I assumed it was a quick proof of concept and just overlooked it :P >>> >>> >>> Thanks! >>> >>> >>> hmm but we have FOLL_LONGTERM as an adjunct to FOLL_PIN (doesn't make sense >>> without - any checks that exist for that btw should be extended to this noew >>> flag). >>> >>> Also don't we want to encode the legacy aspect here? >>> >>> Maybe FOLL_LONGTERM_LEGACY_READONLY? Naming is hard :) >> >> I'm confused about the _READONLY, well. and the FOLL_PIN_NO_GUP_WRITE. >> >> We want to longterm write-pin. >> >> @Pankaj, how come you would call this "FOLL_PIN_NO_GUP_WRITE" -- why "no GUP >> write" ? >> >> I agree that someting like FOLL_LONGTERM_LEGACY_* is the right thing to do, but >> I don't see where this is "no write" or "readonly" ? > > I based it on Gupta saying 'without kernel GUP writes, and therefore not > impacting dirty tracking' > > I mean I think we definitely need some clarification here yes :) > > Not really got the bandwidth to dig deep into GUP again :P I think the KVM gueest *will* write to these pages. By disallowing writable LONGTERM pins on FSes we broke one existing use case that was relying on that to work. -- Cheers, David