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[159.2.239.150]) by smtp.gmail.com with ESMTPSA id 6a1803df08f44-91c7f6ef1b7sm45505406d6.7.2026.10.29.07.16.29 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 29 Oct 2026 07:16:29 -0700 (PDT) Received: from jgg by wakko with local (Exim 4.97) (envelope-from ) id 1xMQvb-0000000FihF-2QML; Thu, 29 Oct 2026 11:16:27 -0300 Date: Thu, 29 Oct 2026 11:16:27 -0300 From: Jason Gunthorpe To: Nikolay Borisov Cc: Jiri Pirko , linux-coco@lists.linux.dev, linux-kernel@vger.kernel.org, linux-api@vger.kernel.org, x86@kernel.org, kvm@vger.kernel.org, linux-doc@vger.kernel.org, david.quigley@intel.com, lukas@wunner.de, ksinyuk@kernel.org, rodrigo.vivi@intel.com, cedric.xing@intel.com, sameo@meta.com, drdeeglaze@gmail.com, James.Bottomley@hansenpartnership.com, aik@amd.com, jpiotrowski@nvidia.com, qinkun@google.com, pgonda@google.com, jic23@kernel.org, alistair.francis@wdc.com, ankita@nvidia.com, suzuki.poulose@arm.com, kas@kernel.org, rick.p.edgecombe@intel.com, elena.reshetova@intel.com, dave.hansen@linux.intel.com, sathyanarayanan.kuppuswamy@linux.intel.com, peter.fang@intel.com Subject: Re: [PATCH RFC 00/20] attestation: Add a common subsystem and TDX support Message-ID: <20261029141627.GP1685504@ziepe.ca> References: <20261015145053.3664509-1-jiri@resnulli.us> <2a2a5d93-1c10-4533-8709-437ceb6a3f94@suse.com> X-Mailing-List: kvm@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <2a2a5d93-1c10-4533-8709-437ceb6a3f94@suse.com> On Thu, Oct 29, 2026 at 09:37:20AM +0200, Nikolay Borisov wrote: > > > On 15.10.26 г. 17:50 ч., Jiri Pirko wrote: > > From: Jiri Pirko > > > > Linux has several attestation interfaces tied to individual technologies. > > That makes evidence retrieval, measurement registers, device state and > > kernel consumers provider-specific. > > > > This series introduces a common attestation subsystem. Its goal is to > > support platform, TEE and device providers through one model, including > > TPM2, TDX, SEV-SNP, Arm CCA, FIRME, Caliptra and PCI/TSM-backed devices. > > This first series implements the common subsystem and a TDX provider. > > Existing native TDX tsm_mr and tsm_report interfaces remain independent. > > Wasn't config-tsm supposed to be this common attestation subsystem? Was this > discussed when the initial config-tsm was proposed? Why is this coming now? Maybe but it was far too narrowly scoped to do that. config-tsm doesn't even include MRs, they were awkwardly pushed off into another different spot. It just doesn't seem to meet the need, and it can't sanely fit SPDM. > > Attestation devices use CTLV, a schema-driven character-device TLV UAPI. > > Compared with sysfs or configfs, CTLV executes one validated request > > atomically instead of assembling a transaction through several files. > > Compared with netlink, an opened device fd directly identifies authority > > and lifetime, can be delegated normally, and owns its event queue. CTLV > > also provides: > > Assuming we want to go through the route of CTLV, do we really want an > attestation-specific interface, or most of this functionality can > simply be CTLV is not attestation specific.. > implemented as a specific genetlink protocol, utilising all the existing > hardening that has gone into netlink's infrastructure to marshal messages > from userspace to kernel space? Been there, seems like a hard no: https://lore.kernel.org/all/20260721182046.16219426@kernel.org/ And then later this: https://lore.kernel.org/all/20260921131911.532d81f4@kernel.org/ Plus netlink being based around sockets and net namespaces is a very poor fit for something that has nothing to do with net namespaces and really wants a DAC security model. > > 83 files changed, 18084 insertions(+), 28 deletions(-) > > That's an awful lot of code to just move certain binary blobs around > (Judging by what config-tsm is doing ATM). Yeah, netlink is alot of code. ctlv is trying to solve a bigger more general problem than just config-tsm. Attestation is simply the first user as it has some complicated data structure that suits it well. Jason