From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1) server-digest SHA256) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id B3EC7606A31C for ; Tue, 20 Oct 2026 17:06:17 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=lists.infradead.org header.i=@lists.infradead.org header.a=rsa-sha256 header.s=bombadil.20210309 header.b=B+/zDpW2; dkim=pass (1024-bit key, unprotected) header.d=arm.com header.i=@arm.com header.a=rsa-sha256 header.s=foss header.b=C5kzCuEo DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=sfkxhp2YPni25pk9lAqihLFxxjnCFT2yCSxPUm/Y7qE=; b=B+/zDpW2qT/WwxlTFhW67qmpAp LmNPlp/2ju0zDcWUEdHe199t5S277rScD5todWZsvqHPj4TUxY27fD1vk7QwMmZlS74Ixn4vrYmrH IrkK0OncMHQ0a4lujNIz6DofiN8ZqMxsLKLO5eOjb8t9sLJiIYRtwlDNK2dZ7FiUVj+T2NR+o/NEO yOiEgABX57L4bP68YZlPbOctUB7weuwdmro0S5sqHaMLUUAgbA3rwYTWIQCIR6xHeTcqwvjx+lUox e0FPSVU9THaUH4BDxt//z8Qa6hm+TQ5ZyOoF73pn1pGZKsfwLmcswn84ELv5FvrF1OA4iZFBIvK30 ViYsEM9w==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1xJDHT-0000000AJIN-1xuh; Tue, 20 Oct 2026 17:05:45 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1xJDHQ-0000000AJHW-3cgl for linux-arm-kernel@lists.infradead.org; Tue, 20 Oct 2026 17:05:42 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id F28FB1596; Tue, 20 Oct 2026 10:05:35 -0700 (PDT) Received: from e129823.arm.com (e129823.arm.com [10.2.213.3]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 9D8973FA32; Tue, 20 Oct 2026 10:05:37 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=arm.com; s=foss; t=1792515939; bh=Neo80ApyG7pQv+dI5x32cAG8lDQTvw41mtuVfq5grwk=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=C5kzCuEoVbtzk+iW3NiFBraTqEDwSW05GvXjZNIJKIssRTnabAGY5qnWFeWvi7Qrp TsaXg2Z0gZK/lvymuXrTeeDT/lr/mR7zPSYfXJYakHbJbwEpSieg2+zHedWdYsLZYn HUDilYCH9SJKM7sJBM72OfetZnIlq+7/+PNz4g5o= Date: Tue, 20 Oct 2026 18:05:35 +0100 From: Yeoreum Yun To: Jason Gunthorpe Cc: Yeoreum Yun , linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, Lorenzo Pieralisi , Catalin Marinas , Suzuki Poulose , Steven Price , Sami Mujawar , "Aneesh Kumar K.V" , Jiri Pirko , GONG Ruiqi Subject: Re: [PATCH RFC 0/3] firmware: arm_firme: introduce FIRME support for host attestation Message-ID: References: <20261020124536.GM14213@ziepe.ca> <20261020135006.GO14213@ziepe.ca> <20261020143620.GP14213@ziepe.ca> <20261020145806.GQ14213@ziepe.ca> <20261020164755.GR14213@ziepe.ca> X-Archived-By: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20261020164755.GR14213@ziepe.ca> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20261020_100541_234808_019B2379 X-CRM114-Status: GOOD ( 40.26 ) X-Spam-Score: -4.4 (----) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" X-Spam-Status: No, score=-6.2 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS autolearn=no autolearn_force=no version=4.0.1 X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 On Tue, Oct 20, 2026 at 01:47:55PM -0300, Jason Gunthorpe wrote: > On Tue, Oct 20, 2026 at 04:18:45PM +0100, Yeoreum Yun wrote: > > On Tue, Oct 20, 2026 at 11:58:06AM -0300, Jason Gunthorpe wrote: > > > On Tue, Oct 20, 2026 at 03:43:47PM +0100, Yeoreum Yun wrote: > > > > On Tue, Oct 20, 2026 at 11:36:20AM -0300, Jason Gunthorpe wrote: > > > > > On Tue, Oct 20, 2026 at 03:13:19PM +0100, Yeoreum Yun wrote: > > > > > > > I wouldn't over complicated it. We already have smccc bus to do this, > > > > > > > we don't need layered stacks of busses here. Just change smccc bus to > > > > > > > be able to break up the multi-function SMC into several devices. > > > > > > > > > > > > I think my explaination was poor. Apologise... > > > > > > I'm not saying another bus making but just wrapper of smccc-bus APIs > > > > > > for firme specific and definietly, this would separate the > > > > > > multi-function SMC to defien each firme device (attestation and IDE). > > > > > > > > > > I don't see that kind of complexity is necessary.. I think it is > > > > > better to just have the root smcc bus spawn them > > > > > > > > > > > But, the *base* is common. and I couldn't find any proper location to > > > > > > deploy *common* code unless making arm_firme. > > > > > > > > > > What common code excatly? > > > > > > > > > > There shouldn't be? Getting an attestation is entirely orthogonal to > > > > > set link ide, for example? > > > > > > > > > > If you can identify what you think would ever be common that might > > > > > help clarifgy what to do.. > > > > > > > > I mean the BASE service of firme and typical example is shared buffer > > > > allocation. I agree IDE and attestaion service are orthogonal. but > > > > in case of base-service is not. it could be used for both service. > > > > > > It doesn't look like it needs a "shared buffer", just allocate it > > > right before invoking the SMC that needs the memory. Use a simple > > > library function to help allocate it. No need for a struct device > > > layer. > > > > Retrieving a PAT requires a buffer shared between the worlds. Before > > allocating that buffer, the driver needs to query its requirements > > through the BASE service's feature-query calls. > > So? Make the query, allocate the buffer, get the token, free > it. Simple, one driver, no convoluted flows. Use a little library > style call or inline to reduce duplication if eventually necessary. > > > Considering possible extensions to the BASE service, my preference > > would be to expose these operations through firme_device rather than > > standalone library functions. The intention is to keep access to the > > BASE service within FIRME-specific drivers and provide a consistent > > interface for those drivers. > > Try not to overdesign things. If we don't know we need it now based on > how the current spec works don't imagine something else. > > ARM spec design is informed by Linux implemetnation. Having a sane > simple implemtnation in Linux will motivate future specs changes to > align better. > > > If we implments this with library, are you thinking that file should > > be located at driver/firmware/arm_firme or other place? though we make it > > with library, I still think it should be located at > > driver/firmware/arm_firme or some place in arch/arm64, but as > > perspective abstraction to mange firme helpers in one place, > > I think this design seems good. > > Will has indicated a preference for driver/firwmare Okay. with this let me make a driver/firmware/arm_firme as library not a module format and make this library APIs (base, attestation) to be used attestation and other. This means device / driver registeration with smccc and done in driver/attestation/provider but use the APIs from /driver/firmware/arm_firme. Thanks for clarification. let me post next RFCv2 after initial attestation subsystem is settled in :) -- Sincerely, Yeoreum Yun