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=-12.7 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT 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 BC9F0C4741F for ; Thu, 5 Nov 2020 12:57:17 +0000 (UTC) Received: from mm01.cs.columbia.edu (mm01.cs.columbia.edu [128.59.11.253]) by mail.kernel.org (Postfix) with ESMTP id 3881820A8B for ; Thu, 5 Nov 2020 12:57:17 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 3881820A8B Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kvmarm-bounces@lists.cs.columbia.edu Received: from localhost (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id B63B34B772; Thu, 5 Nov 2020 07:57:16 -0500 (EST) X-Virus-Scanned: at lists.cs.columbia.edu Received: from mm01.cs.columbia.edu ([127.0.0.1]) by localhost (mm01.cs.columbia.edu [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id riRIcCr7vWZI; Thu, 5 Nov 2020 07:57:15 -0500 (EST) Received: from mm01.cs.columbia.edu (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id 8EB1F4B7EE; Thu, 5 Nov 2020 07:57:15 -0500 (EST) Received: from localhost (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id 854E04B728 for ; Thu, 5 Nov 2020 07:57:14 -0500 (EST) X-Virus-Scanned: at lists.cs.columbia.edu Received: from mm01.cs.columbia.edu ([127.0.0.1]) by localhost (mm01.cs.columbia.edu [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id mZxRyPFhLnKp for ; Thu, 5 Nov 2020 07:57:13 -0500 (EST) Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by mm01.cs.columbia.edu (Postfix) with ESMTP id 3DF574B727 for ; Thu, 5 Nov 2020 07:57:13 -0500 (EST) 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 E69AD142F; Thu, 5 Nov 2020 04:57:12 -0800 (PST) Received: from donnerap.arm.com (donnerap.cambridge.arm.com [10.1.195.35]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 4869E3F73C; Thu, 5 Nov 2020 04:57:11 -0800 (PST) From: Andre Przywara To: Will Deacon , Catalin Marinas , Ard Biesheuvel , Russell King Subject: [PATCH v2 4/5] arm64: Add support for SMCCC TRNG entropy source Date: Thu, 5 Nov 2020 12:56:55 +0000 Message-Id: <20201105125656.25259-5-andre.przywara@arm.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20201105125656.25259-1-andre.przywara@arm.com> References: <20201105125656.25259-1-andre.przywara@arm.com> Cc: Lorenzo Pieralisi , Linus Walleij , linux-kernel@vger.kernel.org, Mark Brown , Sudeep Holla , kvmarm@lists.cs.columbia.edu, linux-arm-kernel@lists.infradead.org X-BeenThere: kvmarm@lists.cs.columbia.edu X-Mailman-Version: 2.1.14 Precedence: list List-Id: Where KVM/ARM decisions are made List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: kvmarm-bounces@lists.cs.columbia.edu Sender: kvmarm-bounces@lists.cs.columbia.edu The ARM architected TRNG firmware interface, described in ARM spec DEN0098, defines an ARM SMCCC based interface to a true random number generator, provided by firmware. This can be discovered via the SMCCC >=v1.1 interface, and provides up to 192 bits of entropy per call. Hook this SMC call into arm64's arch_get_random_*() implementation, coming to the rescue when the CPU does not implement the ARM v8.5 RNG system registers. For the detection, we piggy back on the PSCI/SMCCC discovery (which gives us the conduit to use (hvc/smc)), then try to call the ARM_SMCCC_TRNG_VERSION function, which returns -1 if this interface is not implemented. Signed-off-by: Andre Przywara --- arch/arm64/include/asm/archrandom.h | 53 ++++++++++++++++++++++++----- 1 file changed, 45 insertions(+), 8 deletions(-) diff --git a/arch/arm64/include/asm/archrandom.h b/arch/arm64/include/asm/archrandom.h index abe07c21da8e..03744f688ca1 100644 --- a/arch/arm64/include/asm/archrandom.h +++ b/arch/arm64/include/asm/archrandom.h @@ -4,13 +4,24 @@ #ifdef CONFIG_ARCH_RANDOM +#include #include #include #include +#define ARM_SMCCC_TRNG_MIN_VERSION 0x10000UL + +extern bool smccc_trng_available; + static inline bool __init smccc_probe_trng(void) { - return false; + struct arm_smccc_res res; + + arm_smccc_1_1_invoke(ARM_SMCCC_TRNG_VERSION, &res); + if ((s32)res.a0 < 0) + return false; + + return res.a0 >= ARM_SMCCC_TRNG_MIN_VERSION; } static inline bool __arm64_rndr(unsigned long *v) @@ -43,26 +54,52 @@ static inline bool __must_check arch_get_random_int(unsigned int *v) static inline bool __must_check arch_get_random_seed_long(unsigned long *v) { + struct arm_smccc_res res; + /* * Only support the generic interface after we have detected * the system wide capability, avoiding complexity with the * cpufeature code and with potential scheduling between CPUs * with and without the feature. */ - if (!cpus_have_const_cap(ARM64_HAS_RNG)) - return false; + if (cpus_have_const_cap(ARM64_HAS_RNG)) + return __arm64_rndr(v); - return __arm64_rndr(v); -} + if (smccc_trng_available) { + arm_smccc_1_1_invoke(ARM_SMCCC_TRNG_RND64, 64, &res); + if ((int)res.a0 < 0) + return false; + *v = res.a3; + return true; + } + + return false; +} static inline bool __must_check arch_get_random_seed_int(unsigned int *v) { + struct arm_smccc_res res; unsigned long val; - bool ok = arch_get_random_seed_long(&val); - *v = val; - return ok; + if (cpus_have_const_cap(ARM64_HAS_RNG)) { + if (arch_get_random_seed_long(&val)) { + *v = val; + return true; + } + return false; + } + + if (smccc_trng_available) { + arm_smccc_1_1_invoke(ARM_SMCCC_TRNG_RND64, 32, &res); + if ((int)res.a0 < 0) + return false; + + *v = res.a3 & GENMASK(31, 0); + return true; + } + + return false; } static inline bool __init __early_cpu_has_rndr(void) -- 2.17.1 _______________________________________________ kvmarm mailing list kvmarm@lists.cs.columbia.edu https://lists.cs.columbia.edu/mailman/listinfo/kvmarm