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, 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 2A6F3C2D0CE for ; Tue, 21 Jan 2020 11:19:03 +0000 (UTC) Received: from mm01.cs.columbia.edu (mm01.cs.columbia.edu [128.59.11.253]) by mail.kernel.org (Postfix) with ESMTP id A66D72253D for ; Tue, 21 Jan 2020 11:19:02 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org A66D72253D Authentication-Results: mail.kernel.org; dmarc=none (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 381F34AFC1; Tue, 21 Jan 2020 06:19:02 -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 UXR-agzZ4CXM; Tue, 21 Jan 2020 06:19:01 -0500 (EST) Received: from mm01.cs.columbia.edu (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id 0B8304AFDD; Tue, 21 Jan 2020 06:19:01 -0500 (EST) Received: from localhost (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id C2BEE4AFDA for ; Tue, 21 Jan 2020 06:18:59 -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 pQedoguxD6mK for ; Tue, 21 Jan 2020 06:18:58 -0500 (EST) Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by mm01.cs.columbia.edu (Postfix) with ESMTP id 535B440456 for ; Tue, 21 Jan 2020 06:18:58 -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 EA6351FB; Tue, 21 Jan 2020 03:18:57 -0800 (PST) Received: from localhost (unknown [10.37.6.20]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 602CF3F6C4; Tue, 21 Jan 2020 03:18:57 -0800 (PST) Date: Tue, 21 Jan 2020 11:18:55 +0000 From: Andrew Murray To: Will Deacon Subject: Re: [PATCH v3 2/3] KVM: arm64: limit PMU version to ARMv8.4 Message-ID: <20200121111855.GA5109@e119886-lin.cambridge.arm.com> References: <20200102123905.29360-1-andrew.murray@arm.com> <20200102123905.29360-3-andrew.murray@arm.com> <336acb6b88c2df5e6114e6f8811687e4@kernel.org> <20200121090420.GA9722@willie-the-truck> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20200121090420.GA9722@willie-the-truck> User-Agent: Mutt/1.10.1+81 (426a6c1) (2018-08-26) Cc: Marc Zyngier , Catalin Marinas , 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: , 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 On Tue, Jan 21, 2020 at 09:04:21AM +0000, Will Deacon wrote: > On Mon, Jan 20, 2020 at 05:55:17PM +0000, Marc Zyngier wrote: > > On 2020-01-02 12:39, Andrew Murray wrote: > > > ARMv8.5-PMU introduces 64-bit event counters, however KVM doesn't yet > > > support this. Let's trap the Debug Feature Registers in order to limit > > > PMUVer/PerfMon in the Debug Feature Registers to PMUv3 for ARMv8.4. > > > > > > Signed-off-by: Andrew Murray > > > Reviewed-by: Suzuki K Poulose > > > --- > > > arch/arm64/include/asm/sysreg.h | 4 ++++ > > > arch/arm64/kvm/sys_regs.c | 36 +++++++++++++++++++++++++++++++-- > > > 2 files changed, 38 insertions(+), 2 deletions(-) > > > > > > diff --git a/arch/arm64/include/asm/sysreg.h > > > b/arch/arm64/include/asm/sysreg.h > > > index 6e919fafb43d..1b74f275a115 100644 > > > --- a/arch/arm64/include/asm/sysreg.h > > > +++ b/arch/arm64/include/asm/sysreg.h > > > @@ -672,6 +672,10 @@ > > > #define ID_AA64DFR0_TRACEVER_SHIFT 4 > > > #define ID_AA64DFR0_DEBUGVER_SHIFT 0 > > > > > > +#define ID_DFR0_PERFMON_SHIFT 24 > > > + > > > +#define ID_DFR0_EL1_PMUVER_8_4 5 > > > + > > > #define ID_ISAR5_RDM_SHIFT 24 > > > #define ID_ISAR5_CRC32_SHIFT 16 > > > #define ID_ISAR5_SHA2_SHIFT 12 > > > diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c > > > index 9f2165937f7d..61b984d934d1 100644 > > > --- a/arch/arm64/kvm/sys_regs.c > > > +++ b/arch/arm64/kvm/sys_regs.c > > > @@ -668,6 +668,37 @@ static bool > > > pmu_access_event_counter_el0_disabled(struct kvm_vcpu *vcpu) > > > return check_pmu_access_disabled(vcpu, ARMV8_PMU_USERENR_ER | > > > ARMV8_PMU_USERENR_EN); > > > } > > > > > > +static bool access_id_aa64dfr0_el1(struct kvm_vcpu *vcpu, > > > + struct sys_reg_params *p, > > > + const struct sys_reg_desc *rd) > > > +{ > > > + if (p->is_write) > > > + return write_to_read_only(vcpu, p, rd); > > > + > > > + /* Limit guests to PMUv3 for ARMv8.4 */ > > > + p->regval = read_sanitised_ftr_reg(SYS_ID_AA64DFR0_EL1); > > > + p->regval = cpuid_feature_cap_signed_field_width(p->regval, > > > + ID_AA64DFR0_PMUVER_SHIFT, > > > + 4, ID_DFR0_EL1_PMUVER_8_4); > > > + > > > + return p->regval; > > > > If feels very odd to return the register value in place of a something > > that actually indicates whether we should update the PC or not. I have > > no idea what is happening here in this case. > > Crikey, yes, I missed that and it probably explains why the code looks so > odd. Andrew -- is there a missing hunk or something here? Doh, it should always return true. Nothing missing here - sometimes I also look at my own code and have no idea what I was thinking. Thanks, Andrew Murray > > Will _______________________________________________ kvmarm mailing list kvmarm@lists.cs.columbia.edu https://lists.cs.columbia.edu/mailman/listinfo/kvmarm