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=-10.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 ECBD0C433E2 for ; Fri, 4 Sep 2020 16:15:22 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9D32920772 for ; Fri, 4 Sep 2020 16:15:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1599236122; bh=MLCvWs5mMUOuDyA36Cda3ffiqLz/l2nBWOyu6v+gLSI=; h=Date:From:To:Cc:Subject:In-Reply-To:References:List-ID:From; b=0D2RxVcc3220Op7egCP1LF8ftBg7F+mQs/d51RMq3uTDEiffequUOfjGZNCN74nJu KlkKTMBvDBhJOacrDIgSvwNQqRoyhigoQFAJyIE0besPu2YqVsWc8ZxdPHoRtR4pXq tX4c1rVdTIETtMBWPIgyB5yxKQ+E8Mga+HDhDhsk= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726154AbgIDQPQ (ORCPT ); Fri, 4 Sep 2020 12:15:16 -0400 Received: from mail.kernel.org ([198.145.29.99]:57070 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726892AbgIDQPH (ORCPT ); Fri, 4 Sep 2020 12:15:07 -0400 Received: from disco-boy.misterjones.org (disco-boy.misterjones.org [51.254.78.96]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 9CE6220772; Fri, 4 Sep 2020 16:15:05 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1599236105; bh=MLCvWs5mMUOuDyA36Cda3ffiqLz/l2nBWOyu6v+gLSI=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=ylfjen9OVhEAldXi2YL5m/SJwvfw2FzkZFvwilNCdh//faS7ZM2l3F7NBZHyuuMOT 2tltCwR2Liv05wA0nPm3STMQXq/1gsz1GB65Ha8dkr1Lg/8YBMQLZ0/LAbMqvW4Ck6 qBtu3UNBt0zyLCENgs3p6q75rIvyDtJsoqKi9zP4= Received: from 78.163-31-62.static.virginmediabusiness.co.uk ([62.31.163.78] helo=wait-a-minute.misterjones.org) by disco-boy.misterjones.org with esmtpsa (TLS1.3:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1kEEMh-009Dk6-W6; Fri, 04 Sep 2020 17:15:04 +0100 Date: Fri, 04 Sep 2020 17:15:01 +0100 Message-ID: <87eenhr01m.wl-maz@kernel.org> From: Marc Zyngier To: Jianyong Wu Cc: netdev@vger.kernel.org, yangbo.lu@nxp.com, john.stultz@linaro.org, tglx@linutronix.de, pbonzini@redhat.com, sean.j.christopherson@intel.com, richardcochran@gmail.com, Mark.Rutland@arm.com, will@kernel.org, suzuki.poulose@arm.com, steven.price@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, nd@arm.com Subject: Re: [PATCH v14 07/10] arm64/kvm: Add hypercall service for kvm ptp. In-Reply-To: <20200904092744.167655-8-jianyong.wu@arm.com> References: <20200904092744.167655-1-jianyong.wu@arm.com> <20200904092744.167655-8-jianyong.wu@arm.com> User-Agent: Wanderlust/2.15.9 (Almost Unreal) SEMI-EPG/1.14.7 (Harue) FLIM/1.14.9 (=?UTF-8?B?R29qxY0=?=) APEL/10.8 EasyPG/1.0.0 Emacs/26.3 (x86_64-pc-linux-gnu) MULE/6.0 (HANACHIRUSATO) MIME-Version: 1.0 (generated by SEMI-EPG 1.14.7 - "Harue") Content-Type: text/plain; charset=US-ASCII X-SA-Exim-Connect-IP: 62.31.163.78 X-SA-Exim-Rcpt-To: jianyong.wu@arm.com, netdev@vger.kernel.org, yangbo.lu@nxp.com, john.stultz@linaro.org, tglx@linutronix.de, pbonzini@redhat.com, sean.j.christopherson@intel.com, richardcochran@gmail.com, Mark.Rutland@arm.com, will@kernel.org, suzuki.poulose@arm.com, steven.price@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, nd@arm.com X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on disco-boy.misterjones.org); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 04 Sep 2020 10:27:41 +0100, Jianyong Wu wrote: > > ptp_kvm will get this service through smccc call. > The service offers wall time and counter cycle of host for guest. > caller must explicitly determines which cycle of virtual counter or > physical counter to return if it needs counter cycle. > > Signed-off-by: Jianyong Wu > --- > arch/arm64/kvm/Kconfig | 6 +++++ > arch/arm64/kvm/arch_timer.c | 2 +- > arch/arm64/kvm/hypercalls.c | 49 ++++++++++++++++++++++++++++++++++++ > include/kvm/arm_arch_timer.h | 1 + > include/linux/arm-smccc.h | 16 ++++++++++++ > 5 files changed, 73 insertions(+), 1 deletion(-) > > diff --git a/arch/arm64/kvm/Kconfig b/arch/arm64/kvm/Kconfig > index 318c8f2df245..bbdfacec4813 100644 > --- a/arch/arm64/kvm/Kconfig > +++ b/arch/arm64/kvm/Kconfig > @@ -60,6 +60,12 @@ config KVM_ARM_PMU > config KVM_INDIRECT_VECTORS > def_bool HARDEN_BRANCH_PREDICTOR || RANDOMIZE_BASE > > +config ARM64_KVM_PTP_HOST > + bool "KVM PTP clock host service for arm64" The "for arm64" is not that useful. > + default y > + help > + virtual kvm ptp clock hypercall service for arm64 > + I'm not keen on making this a compile option, because whatever is not always on ends up bit-rotting. Please drop the option. > endif # KVM > > endif # VIRTUALIZATION > diff --git a/arch/arm64/kvm/arch_timer.c b/arch/arm64/kvm/arch_timer.c > index 32ba6fbc3814..eb85f6701845 100644 > --- a/arch/arm64/kvm/arch_timer.c > +++ b/arch/arm64/kvm/arch_timer.c > @@ -81,7 +81,7 @@ u64 timer_get_cval(struct arch_timer_context *ctxt) > } > } > > -static u64 timer_get_offset(struct arch_timer_context *ctxt) > +u64 timer_get_offset(struct arch_timer_context *ctxt) > { > struct kvm_vcpu *vcpu = ctxt->vcpu; > > diff --git a/arch/arm64/kvm/hypercalls.c b/arch/arm64/kvm/hypercalls.c > index 901c60f119c2..2628ddc13abd 100644 > --- a/arch/arm64/kvm/hypercalls.c > +++ b/arch/arm64/kvm/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 = -1; > +#endif Please move all the PTP-related code to its own function, rather than keeping it in the main HVC dispatcher. Also assigning a negative value to something that is unsigned hurts my eyes. Consider using ~0UL instead. See the comment below though. > u32 func_id = smccc_get_function(vcpu); > u64 val[4] = {SMCCC_RET_NOT_SUPPORTED}; > u32 feature; > @@ -21,6 +26,10 @@ int kvm_hvc_call_handler(struct kvm_vcpu *vcpu) > val[0] = ARM_SMCCC_VERSION_1_1; > break; > case ARM_SMCCC_ARCH_FEATURES_FUNC_ID: > + /* > + * Note: keep in mind that feature is u32 and smccc_get_arg1 > + * will return u64, so need auto cast here. > + */ > feature = smccc_get_arg1(vcpu); > switch (feature) { > case ARM_SMCCC_ARCH_WORKAROUND_1: > @@ -70,7 +79,47 @@ 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. This comment doesn't match what I read below. > + */ > + 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] = systime_snapshot.real; > + /* > + * which of virtual counter or physical counter being > + * asked for is decided by the r1 value of smccc nit: s/smccc/SMCCC/ > + * call. If no invalid r1 value offered, default cycle nit: If r1 is an invalid value... > + * value(-1) will return. nit: will be returned. > + */ > + feature = smccc_get_arg1(vcpu); > + switch (feature) { > + case ARM_PTP_VIRT_COUNTER: > + cycles = systime_snapshot.cycles - > + vcpu_read_sys_reg(vcpu, CNTVOFF_EL2); nit: On a single line, please. > + break; > + case ARM_PTP_PHY_COUNTER: > + cycles = systime_snapshot.cycles; > + break; It'd be a lot clearer if you had a default: case here, handling the invalid case. > + } > + val[1] = cycles; Given that cycles is a 64bit value, how does it work for a 32bit guest? Or have you removed support for 32bit guests altogether? > + break; > +#endif > default: > return kvm_psci_call(vcpu); > } > diff --git a/include/kvm/arm_arch_timer.h b/include/kvm/arm_arch_timer.h > index 51c19381108c..5a2b6da9be7a 100644 > --- a/include/kvm/arm_arch_timer.h > +++ b/include/kvm/arm_arch_timer.h > @@ -105,5 +105,6 @@ void kvm_arm_timer_write_sysreg(struct kvm_vcpu *vcpu, > /* Needed for tracing */ > u32 timer_get_ctl(struct arch_timer_context *ctxt); > u64 timer_get_cval(struct arch_timer_context *ctxt); > +u64 timer_get_offset(struct arch_timer_context *ctxt); > > #endif > diff --git a/include/linux/arm-smccc.h b/include/linux/arm-smccc.h > index f7b5dd7dbf9f..0724840eb5f7 100644 > --- a/include/linux/arm-smccc.h > +++ b/include/linux/arm-smccc.h > @@ -103,6 +103,7 @@ > > /* KVM "vendor specific" services */ > #define ARM_SMCCC_KVM_FUNC_FEATURES 0 > +#define ARM_SMCCC_KVM_FUNC_KVM_PTP 1 > #define ARM_SMCCC_KVM_FUNC_FEATURES_2 127 > #define ARM_SMCCC_KVM_NUM_FUNCS 128 > > @@ -112,6 +113,21 @@ > ARM_SMCCC_OWNER_VENDOR_HYP, \ > ARM_SMCCC_KVM_FUNC_FEATURES) > > +/* > + * ptp_kvm is a feature used for time sync between vm and host. > + * ptp_kvm module in guest kernel will get service from host using > + * this hypercall ID. > + */ > +#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) > + > +/* ptp_kvm counter type ID */ > +#define ARM_PTP_VIRT_COUNTER 0 > +#define ARM_PTP_PHY_COUNTER 1 > + > /* Paravirtualised time calls (defined by ARM DEN0057A) */ > #define ARM_SMCCC_HV_PV_TIME_FEATURES \ > ARM_SMCCC_CALL_VAL(ARM_SMCCC_FAST_CALL, \ > -- > 2.17.1 > > Thanks, M. -- Without deviation from the norm, progress is not possible.