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 023372D73A3 for ; Fri, 5 Dec 2025 07:15:58 +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=1764918959; cv=none; b=JGhDvzx62XjdRndf3sqt9KRKnVzq8NSpg4CcenKcY5Y5JEvWljrUStrm24E1eizwWLRpTVQ5jstwvSPlPudOomN1BtMVA/MtYena2ljRtYnByJFsEtOxkeAyBlANH33R97K8opm2uo8c3pD3sk5sRBYjGQUfAYrFKPIPvl/TgtM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1764918959; c=relaxed/simple; bh=a+g5PqYgQ2xiTh3oOMNBb7FVVBwxlJcpvj/PQQU5xpA=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=elto5c5lQWhxsr8UK5/fTGj8OT9u05iUR3s0P8D3d95urM+Ys2Bs1XspcPsmLKM5jOZJLYoJm6AnSDVTP1vvdURQEE+opgjBBNRn0q7+Tkvglk2f1uTPvSLkR++IGfsBvIqBqDnxJgehPP+F8cdZw2aLDvDPMVYut/JO5Yo3Up0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=H6KJ8KRk; 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="H6KJ8KRk" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 97277C4CEF1; Fri, 5 Dec 2025 07:15:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1764918958; bh=a+g5PqYgQ2xiTh3oOMNBb7FVVBwxlJcpvj/PQQU5xpA=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=H6KJ8KRkWUWqEVHPFyLg9y5J16i2rKuaGcdwtjoht61A7MOSLVdVYIWNF/kBlipmI XFzxA4gLWm0bSzAVjyUAgOFMv8c+wM0hd3dg0CeVk3OsSve00jMIWIloHWwMMAUC8X yKImQG5+2OIOkiYIHTnufDaKAWclX+nXI5hxC1TxzOC4y9Nwu4TfJZTsNCxBbs28j9 R8pDMkTD/o4Fy8+kO9BLZa7qzQraqPktg+gPv9Z8S+XwLowunARiRiUUu8ftMcGUKc aGwN7gVDgfufA2/RaG9uH1FNYLQldNbd8friiVLv/sRogJOCOybxCcaeWAi25Lz8iK 6DnEKkbx2w9MQ== Message-ID: Date: Fri, 5 Dec 2025 08:15:51 +0100 Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [RFC PATCH 0/2] KVM: pfncache: Support guest_memfd without direct map To: David Woodhouse , Brendan Jackman , Takahiro Itazuri , kvm@vger.kernel.org, Paolo Bonzini Cc: Sean Christopherson , Vitaly Kuznetsov , Fuad Tabba , Paul Durrant , Nikita Kalyazin , Patrick Roy , Takahiro Itazuri References: <20251203144159.6131-1-itazur@amazon.com> From: "David Hildenbrand (Red Hat)" Content-Language: en-US In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 12/4/25 23:31, David Woodhouse wrote: > On Wed, 2025-12-03 at 17:06 +0000, Brendan Jackman wrote: >> Makes sense. I didn't properly explore if there are any challenges with >> making vmalloc aware of it, but assuming there are no issues there I >> don't think setting up an mm-local region is very challinging [1]. I >> have the impression the main reason there isn't already an mm-local >> region is just that the right usecase hasn't come along yet? > > I'm fairly sure we have a *usecase* for mm-local. Haha, I just skimmed over this patch and wondered "is mm-local a new mm branch we want to have" :) > > And since researchers dusted off our XSA-289 advisory from 2019, > rediscovered it and called it 'L1TF reloaded' and then expressed > surprise that environments which have been using mm-local ever since > those days don't actually leak secrets from one guest to another... I'd > kind of hope that everyone else has come round to our way of thinking > that we have a usecase for mm-local too? :) Yeah, I would assume that we have such use cases indeed. -- Cheers David