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=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,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 BF457C433E0 for ; Fri, 22 May 2020 14:18:32 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8738222211 for ; Fri, 22 May 2020 14:18:32 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730007AbgEVOSb (ORCPT ); Fri, 22 May 2020 10:18:31 -0400 Received: from foss.arm.com ([217.140.110.172]:36348 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729399AbgEVOSb (ORCPT ); Fri, 22 May 2020 10:18:31 -0400 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 AD068D6E; Fri, 22 May 2020 07:18:30 -0700 (PDT) Received: from [192.168.1.84] (unknown [172.31.20.19]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 05A2A3F68F; Fri, 22 May 2020 07:18:27 -0700 (PDT) Subject: Re: [RFC PATCH v12 07/11] psci: Add hypercall service for kvm ptp. To: Jianyong Wu , netdev@vger.kernel.org, yangbo.lu@nxp.com, john.stultz@linaro.org, tglx@linutronix.de, pbonzini@redhat.com, sean.j.christopherson@intel.com, maz@kernel.org, richardcochran@gmail.com, Mark.Rutland@arm.com, will@kernel.org, suzuki.poulose@arm.com Cc: linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org, Steve.Capper@arm.com, Kaly.Xin@arm.com, justin.he@arm.com, Wei.Chen@arm.com, nd@arm.com References: <20200522083724.38182-1-jianyong.wu@arm.com> <20200522083724.38182-8-jianyong.wu@arm.com> From: Steven Price Message-ID: <87fce07b-d0f5-47b0-05ce-dd664ce53eec@arm.com> Date: Fri, 22 May 2020 15:18:22 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.7.0 MIME-Version: 1.0 In-Reply-To: <20200522083724.38182-8-jianyong.wu@arm.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-GB Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 22/05/2020 09:37, Jianyong Wu wrote: > ptp_kvm modules will get this service through smccc call. > The service offers real time and counter cycle of host for guest. > Also let caller determine which cycle of virtual counter or physical counter > to return. > > Signed-off-by: Jianyong Wu > --- > include/linux/arm-smccc.h | 14 ++++++++++++ > virt/kvm/Kconfig | 4 ++++ > virt/kvm/arm/hypercalls.c | 47 +++++++++++++++++++++++++++++++++++++++ > 3 files changed, 65 insertions(+) > > diff --git a/include/linux/arm-smccc.h b/include/linux/arm-smccc.h > index bdc0124a064a..badadc390809 100644 > --- a/include/linux/arm-smccc.h > +++ b/include/linux/arm-smccc.h > @@ -94,6 +94,8 @@ > > /* KVM "vendor specific" services */ > #define ARM_SMCCC_KVM_FUNC_FEATURES 0 > +#define ARM_SMCCC_KVM_FUNC_KVM_PTP 1 > +#define ARM_SMCCC_KVM_FUNC_KVM_PTP_PHY 2 > #define ARM_SMCCC_KVM_FUNC_FEATURES_2 127 > #define ARM_SMCCC_KVM_NUM_FUNCS 128 > > @@ -103,6 +105,18 @@ > ARM_SMCCC_OWNER_VENDOR_HYP, \ > ARM_SMCCC_KVM_FUNC_FEATURES) > > +#define ARM_SMCCC_VENDOR_HYP_KVM_PTP_FUNC_ID \ > + ARM_SMCCC_CALL_VAL(ARM_SMCCC_FAST_CALL, \ > + ARM_SMCCC_SMC_32, \ > + ARM_SMCCC_OWNER_VENDOR_HYP, \ > + ARM_SMCCC_KVM_FUNC_KVM_PTP) > + > +#define ARM_SMCCC_VENDOR_HYP_KVM_PTP_PHY_FUNC_ID \ > + ARM_SMCCC_CALL_VAL(ARM_SMCCC_FAST_CALL, \ > + ARM_SMCCC_SMC_32, \ > + ARM_SMCCC_OWNER_VENDOR_HYP, \ > + ARM_SMCCC_KVM_FUNC_KVM_PTP_PHY) > + > #ifndef __ASSEMBLY__ > > #include > diff --git a/virt/kvm/Kconfig b/virt/kvm/Kconfig > index aad9284c043a..bf820811e815 100644 > --- a/virt/kvm/Kconfig > +++ b/virt/kvm/Kconfig > @@ -60,3 +60,7 @@ config HAVE_KVM_VCPU_RUN_PID_CHANGE > > config HAVE_KVM_NO_POLL > bool > + > +config ARM64_KVM_PTP_HOST > + def_bool y > + depends on ARM64 && KVM > diff --git a/virt/kvm/arm/hypercalls.c b/virt/kvm/arm/hypercalls.c > index db6dce3d0e23..c964122f8dae 100644 > --- a/virt/kvm/arm/hypercalls.c > +++ b/virt/kvm/arm/hypercalls.c > @@ -3,6 +3,7 @@ > > #include > #include > +#include > > #include > > @@ -11,6 +12,10 @@ > > int kvm_hvc_call_handler(struct kvm_vcpu *vcpu) > { > +#ifdef CONFIG_ARM64_KVM_PTP_HOST > + struct system_time_snapshot systime_snapshot; > + u64 cycles; > +#endif > u32 func_id = smccc_get_function(vcpu); > u32 val[4] = {SMCCC_RET_NOT_SUPPORTED}; > u32 feature; > @@ -70,7 +75,49 @@ int kvm_hvc_call_handler(struct kvm_vcpu *vcpu) > break; > case ARM_SMCCC_VENDOR_HYP_KVM_FEATURES_FUNC_ID: > val[0] = BIT(ARM_SMCCC_KVM_FUNC_FEATURES); > + > +#ifdef CONFIG_ARM64_KVM_PTP_HOST > + val[0] |= BIT(ARM_SMCCC_KVM_FUNC_KVM_PTP); > +#endif > break; > + > +#ifdef CONFIG_ARM64_KVM_PTP_HOST > + /* > + * This serves virtual kvm_ptp. > + * Four values will be passed back. > + * reg0 stores high 32-bit host ktime; > + * reg1 stores low 32-bit host ktime; > + * reg2 stores high 32-bit difference of host cycles and cntvoff; > + * reg3 stores low 32-bit difference of host cycles and cntvoff. > + */ > + case ARM_SMCCC_VENDOR_HYP_KVM_PTP_FUNC_ID: > + /* > + * system time and counter value must captured in the same > + * time to keep consistency and precision. > + */ > + ktime_get_snapshot(&systime_snapshot); > + if (systime_snapshot.cs_id != CSID_ARM_ARCH_COUNTER) > + break; > + val[0] = upper_32_bits(systime_snapshot.real); > + val[1] = lower_32_bits(systime_snapshot.real); > + /* > + * which of virtual counter or physical counter being > + * asked for is decided by the first argument. > + */ > + feature = smccc_get_arg1(vcpu); > + switch (feature) { > + case ARM_SMCCC_VENDOR_HYP_KVM_PTP_PHY_FUNC_ID: > + cycles = systime_snapshot.cycles; > + break; > + default: There's something a bit odd here. ARM_SMCCC_VENDOR_HYP_KVM_PTP_FUNC_ID and ARM_SMCCC_VENDOR_HYP_KVM_PTP_PHY_FUNC_ID look like they should be names of separate (top-level) functions, but actually the _PHY_ one is a parameter for the first. If the intention is to have a parameter then it would be better to pick a better name for the _PHY_ define and not define it using ARM_SMCCC_CALL_VAL. Second the use of "default:" means that there's no possibility to later extend this interface for more clocks if needed in the future. Alternatively you could indeed implement as two top-level functions and change this to a... switch (func_id) ... along with multiple case labels as the functions would obviously be mostly the same. Also a minor style issue - you might want to consider splitting this into it's own function. Finally I do think it would be useful to add some documentation of the new SMC calls. It would be easier to review the interface based on that documentation rather than trying to reverse-engineer the interface from the code. Steve > + cycles = systime_snapshot.cycles - > + vcpu_vtimer(vcpu)->cntvoff; > + } > + val[2] = upper_32_bits(cycles); > + val[3] = lower_32_bits(cycles); > + break; > +#endif > + > default: > return kvm_psci_call(vcpu); > } >