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 800753128A2; Wed, 27 Aug 2025 13:08:12 +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=1756300093; cv=none; b=otIbaPzLvTm5l08o87RUzDxI+PAwaMdVlrg8jKjkLEpkYuuQyW50K/zSrN7y4Rc6O/TmmDHuJ8joYfYm3olayIsg6xP/1ZzYAve1ooMVwSoqyKN5cgPnWvjO+L2fRg2Sl9Msb5MVTUsMFhM4jYWkPu4JJRGd3BjNl8z5NmX0tFg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1756300093; c=relaxed/simple; bh=IpEGFEEfU545ej3QeF5+hs5SmtlfBlWhDI8ZhRwmlgs=; h=Date:Message-ID:From:To:Cc:Subject:In-Reply-To:References: MIME-Version:Content-Type; b=KUqNBi0tmBsF6Cr6phR9xYpDPct0CBwXs5R8bwqIUEbTDa4opY1kFL0y6fAx4Zf9BZ28LtRFjDQIORkT6ZUC8xK1tNIB0NOshmTBOG0zE6jaG1Ou/43xn6uJhEPhwbs6fJiiVuU5rvgdiNb9uNvZc7/pmQMx7+A9d3R5DaqsIw0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=snBJ2WlH; 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="snBJ2WlH" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 187D9C4CEEB; Wed, 27 Aug 2025 13:08:12 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1756300092; bh=IpEGFEEfU545ej3QeF5+hs5SmtlfBlWhDI8ZhRwmlgs=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=snBJ2WlHLIctRupH0IhLfUosaWzE7Cju4kyy0lsniZeIChbOLef9dHdVmypF8wmtx GTxBQaL2ur3CWyPzoUipmCJMQb5gql+q8rE140bjVEJaa1tHLJt0AhkE6g7BE+i+Fp IFBTiLevWOnfXr4ryw1r6Fq0G9Tmg2MIXHrq4TzdAxIRx+bUNbOvPbVMDgoGTxRfQC Ujl7kQdI4Tq1m801f4hO7W3HBcGpBaSf8vs7/3xfY9aTEeZGHpkztdLOIPIjuvkyZT 08+FQmvxN7zOdv2ybOlfSzRuL19cKPM9ZicK2Mw71lZyPcfpZqaSqcHTbe5XGoY422 FSmkjaloeEqqw== Received: from sofa.misterjones.org ([185.219.108.64] helo=goblin-girl.misterjones.org) by disco-boy.misterjones.org with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.98.2) (envelope-from ) id 1urFsn-00000000vBX-20Bc; Wed, 27 Aug 2025 13:08:09 +0000 Date: Wed, 27 Aug 2025 14:08:09 +0100 Message-ID: <86frdcewue.wl-maz@kernel.org> From: Marc Zyngier To: Paolo Bonzini Cc: Sean Christopherson , Oliver Upton , kvm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev, linux-kernel@vger.kernel.org, Ira Weiny , Gavin Shan , Shivank Garg , Vlastimil Babka , Xiaoyao Li , David Hildenbrand , Fuad Tabba , Ackerley Tng , Tao Chan , James Houghton Subject: Re: [PATCH v17 00/24] KVM: Enable mmap() for guest_memfd In-Reply-To: <87b10d94-dca2-4ecb-a86f-b38c5c90e0cf@redhat.com> References: <20250729225455.670324-1-seanjc@google.com> <87b10d94-dca2-4ecb-a86f-b38c5c90e0cf@redhat.com> User-Agent: Wanderlust/2.15.9 (Almost Unreal) SEMI-EPG/1.14.7 (Harue) FLIM-LB/1.14.9 (=?UTF-8?B?R29qxY0=?=) APEL-LB/10.8 EasyPG/1.0.0 Emacs/30.1 (aarch64-unknown-linux-gnu) MULE/6.0 (HANACHIRUSATO) Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 (generated by SEMI-EPG 1.14.7 - "Harue") Content-Type: text/plain; charset=US-ASCII X-SA-Exim-Connect-IP: 185.219.108.64 X-SA-Exim-Rcpt-To: pbonzini@redhat.com, seanjc@google.com, oliver.upton@linux.dev, kvm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev, linux-kernel@vger.kernel.org, ira.weiny@intel.com, gshan@redhat.com, shivankg@amd.com, vbabka@suse.cz, xiaoyao.li@intel.com, david@redhat.com, tabba@google.com, ackerleytng@google.com, chentao@kylinos.cn, jthoughton@google.com X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on disco-boy.misterjones.org); SAEximRunCond expanded to false On Wed, 27 Aug 2025 09:43:54 +0100, Paolo Bonzini wrote: > > On 7/30/25 00:54, Sean Christopherson wrote: > > Paolo, > > > > The arm64 patches have been Reviewed-by Marc, and AFAICT the x86 side of > > things is a go. Barring a screwup on my end, this just needs your approval. > > > > Assuming everything looks good, it'd be helpful to get this into kvm/next > > shortly after rc1. The x86 Kconfig changes in particular create semantic > > conflicts with in-flight series. > > > > > > Add support for host userspace mapping of guest_memfd-backed memory for VM > > types that do NOT use support KVM_MEMORY_ATTRIBUTE_PRIVATE (which isn't > > precisely the same thing as CoCo VMs, since x86's SEV-MEM and SEV-ES have > > no way to detect private vs. shared). > > > > mmap() support paves the way for several evolving KVM use cases: > > > > * Allows VMMs like Firecracker to run guests entirely backed by > > guest_memfd [1]. This provides a unified memory management model for > > both confidential and non-confidential guests, simplifying VMM design. > > > > * Enhanced Security via direct map removal: When combined with Patrick's > > series for direct map removal [2], this provides additional hardening > > against Spectre-like transient execution attacks by eliminating the > > need for host kernel direct maps of guest memory. > > > > * Lays the groundwork for *restricted* mmap() support for guest_memfd-backed > > memory on CoCo platforms [3] that permit in-place > > sharing of guest memory with the host. > > > > Based on kvm/queue. > > Applied to kvm/next, thanks! Can you please create a stable branch for these patches? It is quite likely that whatever I queue for 6.18 will conflict with that, and I'd like to be able to resolve the conflicts myself. Thanks, M. -- Without deviation from the norm, progress is not possible.