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Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.90_1 #2 (Red Hat Linux)) id 1gpGYb-0006Xk-4x; Thu, 31 Jan 2019 17:55:21 +0000 Received: from foss.arm.com ([217.140.101.70]) by bombadil.infradead.org with esmtp (Exim 4.90_1 #2 (Red Hat Linux)) id 1gpGYO-0005sc-MN for linux-arm-kernel@lists.infradead.org; Thu, 31 Jan 2019 17:55:18 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.72.51.249]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 490F4A78; Thu, 31 Jan 2019 09:55:08 -0800 (PST) Received: from donnerap.cambridge.arm.com (usa-sjc-imap-foss1.foss.arm.com [10.72.51.249]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id D82133F59C; Thu, 31 Jan 2019 09:55:05 -0800 (PST) Date: Thu, 31 Jan 2019 17:55:02 +0000 From: Andre Przywara To: Jeremy Linton Subject: Re: [PATCH v4 09/12] arm64: Use firmware to detect CPUs that are not affected by Spectre-v2 Message-ID: <20190131175502.12bed0f0@donnerap.cambridge.arm.com> In-Reply-To: <20190125180711.1970973-10-jeremy.linton@arm.com> References: <20190125180711.1970973-1-jeremy.linton@arm.com> <20190125180711.1970973-10-jeremy.linton@arm.com> Organization: ARM X-Mailer: Claws Mail 3.17.3 (GTK+ 2.24.32; aarch64-unknown-linux-gnu) MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190131_095508_857721_029D9EE4 X-CRM114-Status: GOOD ( 18.90 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: stefan.wahren@i2se.com, mlangsdo@redhat.com, suzuki.poulose@arm.com, marc.zyngier@arm.com, catalin.marinas@arm.com, julien.thierry@arm.com, will.deacon@arm.com, linux-kernel@vger.kernel.org, steven.price@arm.com, shankerd@codeaurora.org, ykaukab@suse.de, dave.martin@arm.com, 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 Fri, 25 Jan 2019 12:07:08 -0600 Jeremy Linton wrote: > From: Marc Zyngier > > The SMCCC ARCH_WORKAROUND_1 service can indicate that although the > firmware knows about the Spectre-v2 mitigation, this particular > CPU is not vulnerable, and it is thus not necessary to call > the firmware on this CPU. > > Let's use this information to our benefit. > > Signed-off-by: Marc Zyngier > Signed-off-by: Jeremy Linton Yes, I stumbled over this in the firmware spec as well: Reviewed-by: Andre Przywara Cheers, Andre. > --- > arch/arm64/kernel/cpu_errata.c | 32 +++++++++++++++++++++++--------- > 1 file changed, 23 insertions(+), 9 deletions(-) > > diff --git a/arch/arm64/kernel/cpu_errata.c b/arch/arm64/kernel/cpu_errata.c > index 4d23b4d4cfa8..024c83ffff99 100644 > --- a/arch/arm64/kernel/cpu_errata.c > +++ b/arch/arm64/kernel/cpu_errata.c > @@ -217,22 +217,36 @@ static int detect_harden_bp_fw(void) > case PSCI_CONDUIT_HVC: > arm_smccc_1_1_hvc(ARM_SMCCC_ARCH_FEATURES_FUNC_ID, > ARM_SMCCC_ARCH_WORKAROUND_1, &res); > - if ((int)res.a0 < 0) > + switch ((int)res.a0) { > + case 1: > + /* Firmware says we're just fine */ > + return 0; > + case 0: > + cb = call_hvc_arch_workaround_1; > + /* This is a guest, no need to patch KVM vectors */ > + smccc_start = NULL; > + smccc_end = NULL; > + break; > + default: > return -1; > - cb = call_hvc_arch_workaround_1; > - /* This is a guest, no need to patch KVM vectors */ > - smccc_start = NULL; > - smccc_end = NULL; > + } > break; > > case PSCI_CONDUIT_SMC: > arm_smccc_1_1_smc(ARM_SMCCC_ARCH_FEATURES_FUNC_ID, > ARM_SMCCC_ARCH_WORKAROUND_1, &res); > - if ((int)res.a0 < 0) > + switch ((int)res.a0) { > + case 1: > + /* Firmware says we're just fine */ > + return 0; > + case 0: > + cb = call_smc_arch_workaround_1; > + smccc_start = __smccc_workaround_1_smc_start; > + smccc_end = __smccc_workaround_1_smc_end; > + break; > + default: > return -1; > - cb = call_smc_arch_workaround_1; > - smccc_start = __smccc_workaround_1_smc_start; > - smccc_end = __smccc_workaround_1_smc_end; > + } > break; > > default: _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel