From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-12.5 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 75D3BC433FE for ; Fri, 11 Dec 2020 17:31:59 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3FE6123E1B for ; Fri, 11 Dec 2020 17:31:59 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2395117AbgLKQ1V (ORCPT ); Fri, 11 Dec 2020 11:27:21 -0500 Received: from mail.kernel.org ([198.145.29.99]:44726 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727045AbgLKQ1B (ORCPT ); Fri, 11 Dec 2020 11:27:01 -0500 Date: Fri, 11 Dec 2020 16:26:12 +0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1607703980; bh=D6PkJnLwPkrx/3nU/EoMY178LXorbA8/thVLoD5x+gg=; h=From:To:Cc:Subject:References:In-Reply-To:From; b=sSToW0aVjFM7A46kyj5fNwO6lsvjA8fH1bSfIe2FIt27w1A/uLILWKHpwANn0GkYm m8YSK4wkUsGMLzthrzLiuMX962yLju3OOZvdAJ/KTbDGqmwjlY3gIvFIVm229KHcZ8 5Xbc4KHrmdfwsJ133V83EWMsvcx5PCQp8FpT2FYJDEcHZnMcWrtkohxJUby53gdsyV hmkH9SZfdSs/tc6Nh16K2pBfjwxqu+MQzSiE4ZJeCNtRA2v+f+ncQKBbigjS2eskVv cHP+pNiFeCSwwFDoGatvDwXRzbcwVCGb6FnmaEXCkrk1FzBg4DRElKivXnMIkoflvb Je8MPbDrjFPIw== From: Mark Brown To: Andre Przywara Cc: Will Deacon , Catalin Marinas , Ard Biesheuvel , Russell King , Marc Zyngier , Theodore Ts'o , Sudeep Holla , Mark Rutland , Lorenzo Pieralisi , Linus Walleij , linux-arm-kernel@lists.infradead.org, kvmarm@lists.cs.columbia.edu, linux-kernel@vger.kernel.org Subject: Re: [PATCH v4 4/5] arm64: Add support for SMCCC TRNG entropy source Message-ID: <20201211162612.GF4929@sirena.org.uk> References: <20201211160005.187336-1-andre.przywara@arm.com> <20201211160005.187336-5-andre.przywara@arm.com> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="dWYAkE0V1FpFQHQ3" Content-Disposition: inline In-Reply-To: <20201211160005.187336-5-andre.przywara@arm.com> X-Cookie: Nostalgia isn't what it used to be. User-Agent: Mutt/1.10.1 (2018-07-13) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --dWYAkE0V1FpFQHQ3 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Fri, Dec 11, 2020 at 04:00:04PM +0000, Andre Przywara wrote: > static inline bool __must_check arch_get_random_seed_long(unsigned long = *v) > { > + struct arm_smccc_res res; > + > + /* > + * We prefer the SMCCC call, since its semantics (return actual > + * hardware backed entropy) is closer to the idea behind this > + * function here than what even the RNDRSS register provides > + * (the output of a pseudo RNG freshly seeded by a TRNG). > + */ This logic... > @@ -77,10 +117,20 @@ arch_get_random_seed_long_early(unsigned long *v) > { > WARN_ON(system_state !=3D SYSTEM_BOOTING); > =20 > - if (!__early_cpu_has_rndr()) > - return false; > + if (__early_cpu_has_rndr()) > + return __arm64_rndr(v); > + > + if (smccc_trng_available) { > + struct arm_smccc_res res; > =20 > - return __arm64_rndr(v); > + arm_smccc_1_1_invoke(ARM_SMCCC_TRNG_RND64, 64, &res); > + if ((int)res.a0 >=3D 0) { > + *v =3D res.a3; > + return true; > + } > + } > + > + return false; =2E..seems to also apply here but we prefer the RNDR instead of the SMCC. We probably want to either do the same thing or add a comment saying what's going on. --dWYAkE0V1FpFQHQ3 Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQEzBAABCgAdFiEEreZoqmdXGLWf4p/qJNaLcl1Uh9AFAl/TnaQACgkQJNaLcl1U h9A37gf/YcdpiwbfAu6XhOilbKoh0HHz40BryiT+RzRxWBTZRHBqVwt49G6le4SV pqInBtPCBnSGvT05jK0C8hSzEU6LKN0OrRToGzUJqsMi1Kf7rDwCs6gA6CVURIwY wSXxNuGD3c9dGXCtip4pRhY4qB5PZ9FcVbgWVu84CnrCX6efa7DbDMBLdX7S03g4 NWvYxTwnoVswk5CeltpcHx3xzvY4IH73h5UNycV6UEYj0AiNrKf9YIfIqtk55uLh x+GtUS8mlxj9FDrhW7J2z/+EgDjZ06XF4yP/iVLSDmCaFOwrck0Mi/6ypeF59nMz w2FoqjLlhrzqojVUxLk/SEg4y5jECA== =0YV1 -----END PGP SIGNATURE----- --dWYAkE0V1FpFQHQ3--