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Wed, 03 Jun 2020 00:04:22 -0800 Received: from MTKMBS01N1.mediatek.inc (172.21.101.68) by MTKMBS62DR.mediatek.inc (172.29.94.18) with Microsoft SMTP Server (TLS) id 15.0.1497.2; Wed, 3 Jun 2020 00:54:24 -0700 Received: from mtkcas07.mediatek.inc (172.21.101.84) by mtkmbs01n1.mediatek.inc (172.21.101.68) with Microsoft SMTP Server (TLS) id 15.0.1497.2; Wed, 3 Jun 2020 15:54:16 +0800 Received: from [172.21.77.33] (172.21.77.33) by mtkcas07.mediatek.inc (172.21.101.73) with Microsoft SMTP Server id 15.0.1497.2 via Frontend Transport; Wed, 3 Jun 2020 15:54:16 +0800 Message-ID: <1591170857.19414.5.camel@mtkswgap22> Subject: Re: Security Random Number Generator support From: Neal Liu To: Marc Zyngier Date: Wed, 3 Jun 2020 15:54:17 +0800 In-Reply-To: References: <1591085678-22764-1-git-send-email-neal.liu@mediatek.com> <85dfc0142d3879d50c0ba18bcc71e199@misterjones.org> <1591169342.4878.9.camel@mtkswgap22> X-Mailer: Evolution 3.2.3-0ubuntu6 MIME-Version: 1.0 X-MTK: N X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200603_010431_393966_D2E8787B X-CRM114-Status: GOOD ( 21.09 ) 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: "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" , Julius Werner , Herbert Xu , Arnd Bergmann , Greg Kroah-Hartman , Sean Wang , lkml , wsd_upstream , Crystal Guo =?UTF-8?Q?=28=E9=83=AD=E6=99=B6=29?= , Rob Herring , Neal Liu , Linux Crypto Mailing List , Matt Mackall , Matthias Brugger , linux-mediatek@lists.infradead.org, Ard Biesheuvel , Linux ARM 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 Wed, 2020-06-03 at 08:40 +0100, Marc Zyngier wrote: > On 2020-06-03 08:29, Neal Liu wrote: > > On Tue, 2020-06-02 at 21:02 +0800, Marc Zyngier wrote: > >> On 2020-06-02 13:14, Ard Biesheuvel wrote: > >> > On Tue, 2 Jun 2020 at 10:15, Neal Liu wrote: > >> >> > >> >> These patch series introduce a security random number generator > >> >> which provides a generic interface to get hardware rnd from Secure > >> >> state. The Secure state can be Arm Trusted Firmware(ATF), Trusted > >> >> Execution Environment(TEE), or even EL2 hypervisor. > >> >> > >> >> Patch #1..2 adds sec-rng kernel driver for Trustzone based SoCs. > >> >> For security awareness SoCs on ARMv8 with TrustZone enabled, > >> >> peripherals like entropy sources is not accessible from normal world > >> >> (linux) and rather accessible from secure world (HYP/ATF/TEE) only. > >> >> This driver aims to provide a generic interface to Arm Trusted > >> >> Firmware or Hypervisor rng service. > >> >> > >> >> > >> >> changes since v1: > >> >> - rename mt67xx-rng to mtk-sec-rng since all MediaTek ARMv8 SoCs can > >> >> reuse > >> >> this driver. > >> >> - refine coding style and unnecessary check. > >> >> > >> >> changes since v2: > >> >> - remove unused comments. > >> >> - remove redundant variable. > >> >> > >> >> changes since v3: > >> >> - add dt-bindings for MediaTek rng with TrustZone enabled. > >> >> - revise HWRNG SMC call fid. > >> >> > >> >> changes since v4: > >> >> - move bindings to the arm/firmware directory. > >> >> - revise driver init flow to check more property. > >> >> > >> >> changes since v5: > >> >> - refactor to more generic security rng driver which > >> >> is not platform specific. > >> >> > >> >> *** BLURB HERE *** > >> >> > >> >> Neal Liu (2): > >> >> dt-bindings: rng: add bindings for sec-rng > >> >> hwrng: add sec-rng driver > >> >> > >> > > >> > There is no reason to model a SMC call as a driver, and represent it > >> > via a DT node like this. > >> > >> +1. > >> > >> > It would be much better if this SMC interface is made truly generic, > >> > and wired into the arch_get_random() interface, which can be used much > >> > earlier. > >> > >> Wasn't there a plan to standardize a SMC call to rule them all? > >> > >> M. > > > > Could you give us a hint how to make this SMC interface more generic in > > addition to my approach? > > There is no (easy) way to get platform-independent SMC function ID, > > which is why we encode it into device tree, and provide a generic > > driver. In this way, different devices can be mapped and then get > > different function ID internally. > > The idea is simply to have *one* single ID that caters for all > implementations, just like we did for PSCI at the time. This > requires ARM to edict a standard, which is what I was referring > to above. > > There is zero benefit in having a platform-dependent ID. It just > pointlessly increases complexity, and means we cannot use the RNG > before the firmware tables are available (yes, we need it that > early). > > M. Do you know which ARM expert could edict this standard? Or is there any chance that we can make one? And be reviewed by maintainers? _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel