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=-12.9 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=unavailable 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 6DE81C433DB for ; Fri, 5 Feb 2021 20:04:57 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 2D99964FBA for ; Fri, 5 Feb 2021 20:04:57 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233455AbhBESVg (ORCPT ); Fri, 5 Feb 2021 13:21:36 -0500 Received: from mail.kernel.org ([198.145.29.99]:48914 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233066AbhBEPTg (ORCPT ); Fri, 5 Feb 2021 10:19:36 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id D4A7564F2C; Fri, 5 Feb 2021 17:00:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1612544413; bh=bYsyypHJHkCDMPq/yGSFgDLzazYUpF+GyWHhaLu3g4k=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=b1jCslKGu5syM6wrgfzO+JQED3kse4raQl0d6FfhlQitKk+PIqGWsucshvT5xTTDT pFgPhLBLy0lnyOoljOXKrQtVRJRYMQY0OAWwFJk+4+Fp8+fCoMCCz8RiNq/7A8GvwT scyQNLe4GsQOdJx6RRmimhK+Iv6oHqD20IyhZq7qoah7ToC4DQ5H24blnfQCoo6qxA zJ3fFY25tCWmIi2HnxEzY5JqdsQbVmqld1lGesBnu1pP5ENmCt4t4tE0NUWf9f2GbF qS492rMyHch6HYBMm9czMXIuew2DqXpXu5d/HH0b2PJ6rjESiv0gM/XUS4YUwFRLvT 9NXR0ve6CzKgw== Date: Fri, 5 Feb 2021 17:00:06 +0000 From: Will Deacon To: Marc Zyngier Cc: Steven Price , netdev@vger.kernel.org, yangbo.lu@nxp.com, john.stultz@linaro.org, tglx@linutronix.de, pbonzini@redhat.com, seanjc@google.com, richardcochran@gmail.com, Mark.Rutland@arm.com, suzuki.poulose@arm.com, Andre.Przywara@arm.com, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org, Steve.Capper@arm.com, justin.he@arm.com, jianyong.wu@arm.com, kernel-team@android.com Subject: Re: [PATCH v17 1/7] arm/arm64: Probe for the presence of KVM hypervisor Message-ID: <20210205170005.GC22665@willie-the-truck> References: <20210202141204.3134855-1-maz@kernel.org> <20210202141204.3134855-2-maz@kernel.org> <20210205111921.GA22109@willie-the-truck> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Feb 05, 2021 at 04:50:27PM +0000, Marc Zyngier wrote: > On 2021-02-05 11:19, Will Deacon wrote: > > On Fri, Feb 05, 2021 at 09:11:00AM +0000, Steven Price wrote: > > > On 02/02/2021 14:11, Marc Zyngier wrote: > > > > + for (i = 0; i < 32; ++i) { > > > > + if (res.a0 & (i)) > > > > + set_bit(i + (32 * 0), __kvm_arm_hyp_services); > > > > + if (res.a1 & (i)) > > > > + set_bit(i + (32 * 1), __kvm_arm_hyp_services); > > > > + if (res.a2 & (i)) > > > > + set_bit(i + (32 * 2), __kvm_arm_hyp_services); > > > > + if (res.a3 & (i)) > > > > + set_bit(i + (32 * 3), __kvm_arm_hyp_services); > > > > > > The bit shifts are missing, the tests should be of the form: > > > > > > if (res.a0 & (1 << i)) > > > > > > Or indeed using a BIT() macro. > > > > Maybe even test_bit()? > > Actually, maybe not doing things a-bit-at-a-time is less error prone. > See below what I intend to fold in. > > Thanks, > > M. > > diff --git a/drivers/firmware/smccc/kvm_guest.c > b/drivers/firmware/smccc/kvm_guest.c > index 00bf3c7969fc..08836f2f39ee 100644 > --- a/drivers/firmware/smccc/kvm_guest.c > +++ b/drivers/firmware/smccc/kvm_guest.c > @@ -2,8 +2,8 @@ > > #define pr_fmt(fmt) "smccc: KVM: " fmt > > -#include > #include > +#include > #include > #include > > @@ -13,8 +13,8 @@ static DECLARE_BITMAP(__kvm_arm_hyp_services, > ARM_SMCCC_KVM_NUM_FUNCS) __ro_afte > > void __init kvm_init_hyp_services(void) > { > - int i; > struct arm_smccc_res res; > + u32 val[4]; > > if (arm_smccc_1_1_get_conduit() != SMCCC_CONDUIT_HVC) > return; > @@ -28,16 +28,13 @@ void __init kvm_init_hyp_services(void) > > memset(&res, 0, sizeof(res)); > arm_smccc_1_1_invoke(ARM_SMCCC_VENDOR_HYP_KVM_FEATURES_FUNC_ID, &res); > - for (i = 0; i < 32; ++i) { > - if (res.a0 & (i)) > - set_bit(i + (32 * 0), __kvm_arm_hyp_services); > - if (res.a1 & (i)) > - set_bit(i + (32 * 1), __kvm_arm_hyp_services); > - if (res.a2 & (i)) > - set_bit(i + (32 * 2), __kvm_arm_hyp_services); > - if (res.a3 & (i)) > - set_bit(i + (32 * 3), __kvm_arm_hyp_services); > - } > + > + val[0] = lower_32_bits(res.a0); > + val[1] = lower_32_bits(res.a1); > + val[2] = lower_32_bits(res.a2); > + val[3] = lower_32_bits(res.a3); > + > + bitmap_from_arr32(__kvm_arm_hyp_services, val, ARM_SMCCC_KVM_NUM_FUNCS); Nice! That's loads better. Will