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[47.54.130.67]) by smtp.gmail.com with ESMTPSA id 6a1803df08f44-8ac84cb0474sm121526396d6.40.2026.04.14.05.29.51 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 14 Apr 2026 05:29:51 -0700 (PDT) Received: from jgg by wakko with local (Exim 4.97) (envelope-from ) id 1wCctq-0000000Afc7-2XTs; Tue, 14 Apr 2026 09:29:50 -0300 Date: Tue, 14 Apr 2026 09:29:50 -0300 From: Jason Gunthorpe To: Suzuki K Poulose Cc: Sami Mujawar , Dan Williams , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, catalin.marinas@arm.com, will@kernel.org, thuth@redhat.com, steven.price@arm.com, gshan@redhat.com, YeoReum.Yun@arm.com, cedric.xing@intel.com, Dan Williams , Dionna Glaze , "Aneesh Kumar K . V" , Alexey Kardashevskiy , "linux-coco@lists.linux.dev" Subject: Re: [PATCH 0/3] arm64/virt: Add Arm CCA measurement register support Message-ID: <20260414122950.GW3694781@ziepe.ca> References: <20260413084957.327661-1-sami.mujawar@arm.com> <20260413125925.GK3694781@ziepe.ca> <514ddb27-137b-4223-84fe-2152737db3a6@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <514ddb27-137b-4223-84fe-2152737db3a6@arm.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260414_052953_456173_A0241906 X-CRM114-Status: GOOD ( 13.32 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Tue, Apr 14, 2026 at 11:10:51AM +0100, Suzuki K Poulose wrote: > > Isn't this also sort of incomplete? Doesn't anything serious need > > signed measurements? Isnt't there alot more data that comes out of RMM > > than just a few measurement registers? > As mentioned above, this series adds the support for Runtime Extendible > Measurements (REM in CCA, RTMR on TDX). The RIM+Platform Attestation is > already provided via the TSM_REPORT Okay, but what actual use is this? Extendable measrements with no log Measurement read back without signature What is the use case? What do you imagine any userspace will do with this? Put it in the cover letter. I don't think the raw rmm calls are sufficiently developed to be usable directly by userspace. They are less capable than TPM and even TPM has a lot of software around it to make it useful. Jason