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Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1iwTqy-00046D-2Q; Tue, 28 Jan 2020 16:36:40 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1iwTqu-00045O-VN for linux-arm-kernel@lists.infradead.org; Tue, 28 Jan 2020 16:36:38 +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 1D4D71FB; Tue, 28 Jan 2020 08:36:33 -0800 (PST) Received: from bogus (e103737-lin.cambridge.arm.com [10.1.197.49]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id E072A3F68E; Tue, 28 Jan 2020 08:36:30 -0800 (PST) Date: Tue, 28 Jan 2020 16:36:28 +0000 From: Sudeep Holla To: Benjamin Gaignard Subject: Re: [PATCH v2 0/7] Introduce bus firewall controller framework Message-ID: <20200128163628.GB30489@bogus> References: <20200128153806.7780-1-benjamin.gaignard@st.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20200128153806.7780-1-benjamin.gaignard@st.com> User-Agent: Mutt/1.9.4 (2018-02-28) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200128_083637_053514_DA2E3866 X-CRM114-Status: GOOD ( 13.32 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: robh@kernel.org, loic.pallardy@st.com, arnd@arndb.de, devicetree@vger.kernel.org, gregkh@linuxfoundation.org, s.hauer@pengutronix.de, linux-kernel@vger.kernel.org, system-dt@lists.openampproject.org, broonie@kernel.org, lkml@metux.net, linux-imx@nxp.com, kernel@pengutronix.de, Sudeep Holla , fabio.estevam@nxp.com, stefano.stabellini@xilinx.com, shawnguo@kernel.org, linux-arm-kernel@lists.infradead.org Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Tue, Jan 28, 2020 at 04:37:59PM +0100, Benjamin Gaignard wrote: > Bus firewall framework aims to provide a kernel API to set the configuration > of the harware blocks in charge of busses access control. > > Framework architecture is inspirated by pinctrl framework: > - a default configuration could be applied before bind the driver. > If a configuration could not be applied the driver is not bind > to avoid doing accesses on prohibited regions. > - configurations could be apllied dynamically by drivers. > - device node provides the bus firewall configurations. > > An example of bus firewall controller is STM32 ETZPC hardware block > which got 3 possible configurations: > - trust: hardware blocks are only accessible by software running on trust > zone (i.e op-tee firmware). > - non-secure: hardware blocks are accessible by non-secure software (i.e. > linux kernel). > - coprocessor: hardware blocks are only accessible by the coprocessor. > Up to 94 hardware blocks of the soc could be managed by ETZPC. > /me confused. Is ETZPC accessible from the non-secure kernel space to begin with ? If so, is it allowed to configure hardware blocks as secure or trusted ? I am failing to understand the overall design of a system with ETZPC controller. > At least two other hardware blocks can take benefits of this: > - ARM TZC-400: http://infocenter.arm.com/help/topic/com.arm.doc.100325_0001_02_en/arm_corelink_tzc400_trustzone_address_space_controller_trm_100325_0001_02_en.pdf > which is able to manage up to 8 regions in address space. I strongly have to disagree with the above and NACK any patch trying to do so. AFAIK, no system designed has TZC with non-secure access. So we simply can't access this in the kernel and hence need no driver for the same. Please avoid adding above misleading information in future. -- Regards, Sudeep _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel