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=-15.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,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 81CFBC433DB for ; Wed, 27 Jan 2021 17:42:25 +0000 (UTC) Received: from mm01.cs.columbia.edu (mm01.cs.columbia.edu [128.59.11.253]) by mail.kernel.org (Postfix) with ESMTP id DE04964D9E for ; Wed, 27 Jan 2021 17:42:24 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org DE04964D9E Authentication-Results: mail.kernel.org; dmarc=fail (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 50F874B0DD; Wed, 27 Jan 2021 12:42:24 -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 2gRX9ShqN-Oj; Wed, 27 Jan 2021 12:42:23 -0500 (EST) Received: from mm01.cs.columbia.edu (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id 1CE6D4B112; Wed, 27 Jan 2021 12:42:23 -0500 (EST) Received: from localhost (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id A78EC4B10C for ; Wed, 27 Jan 2021 12:42:21 -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 qt0Li5AUE7fC for ; Wed, 27 Jan 2021 12:42:20 -0500 (EST) Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by mm01.cs.columbia.edu (Postfix) with ESMTP id 60FC94B0DD for ; Wed, 27 Jan 2021 12:42:20 -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 EBBE11FB; Wed, 27 Jan 2021 09:42:19 -0800 (PST) Received: from [192.168.0.110] (unknown [172.31.20.19]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id AA2D63F66E; Wed, 27 Jan 2021 09:42:18 -0800 (PST) Subject: Re: [PATCH v2 6/7] KVM: arm64: Upgrade PMU support to ARMv8.4 To: Marc Zyngier , linux-arm-kernel@lists.infradead.org, kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org References: <20210125122638.2947058-1-maz@kernel.org> <20210125122638.2947058-7-maz@kernel.org> From: Alexandru Elisei Message-ID: <680c2e4f-cc9f-10c1-1158-7de32057fb0d@arm.com> Date: Wed, 27 Jan 2021 17:41:59 +0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.6.1 MIME-Version: 1.0 In-Reply-To: <20210125122638.2947058-7-maz@kernel.org> Content-Language: en-US Cc: kernel-team@android.com 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 Hi Marc, Had another look at the patch, comments below. On 1/25/21 12:26 PM, Marc Zyngier wrote: > Upgrading the PMU code from ARMv8.1 to ARMv8.4 turns out to be > pretty easy. All that is required is support for PMMIR_EL1, which > is read-only, and for which returning 0 is a valid option as long > as we don't advertise STALL_SLOT as an implemented event. > > Let's just do that and adjust what we return to the guest. > > Signed-off-by: Marc Zyngier > --- > arch/arm64/include/asm/sysreg.h | 3 +++ > arch/arm64/kvm/pmu-emul.c | 6 ++++++ > arch/arm64/kvm/sys_regs.c | 11 +++++++---- > 3 files changed, 16 insertions(+), 4 deletions(-) > > diff --git a/arch/arm64/include/asm/sysreg.h b/arch/arm64/include/asm/sysreg.h > index 8b5e7e5c3cc8..2fb3f386588c 100644 > --- a/arch/arm64/include/asm/sysreg.h > +++ b/arch/arm64/include/asm/sysreg.h > @@ -846,7 +846,10 @@ > > #define ID_DFR0_PERFMON_SHIFT 24 > > +#define ID_DFR0_PERFMON_8_0 0x3 > #define ID_DFR0_PERFMON_8_1 0x4 > +#define ID_DFR0_PERFMON_8_4 0x5 > +#define ID_DFR0_PERFMON_8_5 0x6 > > #define ID_ISAR4_SWP_FRAC_SHIFT 28 > #define ID_ISAR4_PSR_M_SHIFT 24 > diff --git a/arch/arm64/kvm/pmu-emul.c b/arch/arm64/kvm/pmu-emul.c > index 398f6df1bbe4..72cd704a8368 100644 > --- a/arch/arm64/kvm/pmu-emul.c > +++ b/arch/arm64/kvm/pmu-emul.c > @@ -795,6 +795,12 @@ u64 kvm_pmu_get_pmceid(struct kvm_vcpu *vcpu, bool pmceid1) > base = 0; > } else { > val = read_sysreg(pmceid1_el0); > + /* > + * Don't advertise STALL_SLOT, as PMMIR_EL0 is handled > + * as RAZ > + */ > + if (vcpu->kvm->arch.pmuver >= ID_AA64DFR0_PMUVER_8_4) > + val &= ~BIT_ULL(ARMV8_PMUV3_PERFCTR_STALL_SLOT - 32); This is confusing the me. We have kvm->arch.pmuver set to the hardware PMU version (as set by __armv8pmu_probe_pmu()), but we ignore it when reporting the PMU version to the guest. Why do we do that? We limit the event number in kvm_pmu_event_mask() based on the hardware PMU version, so even if we advertise Armv8.4 PMU, support for all those extra events added by Arm8.1 PMU is missing (I hope I understood the code correctly). I looked at commit c854188ea010 ("KVM: arm64: limit PMU version to PMUv3 for ARMv8.1") which changed read_id_reg() to report PMUv3 for Armv8.1 unconditionally, and there's no explanation why PMUv3 for Armv8.1 was chosen instead of plain PMUv3 (PMUVer = 0b0100). Thanks, Alex > base = 32; > } > > diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c > index 8f79ec1fffa7..5da536ab738d 100644 > --- a/arch/arm64/kvm/sys_regs.c > +++ b/arch/arm64/kvm/sys_regs.c > @@ -1051,16 +1051,16 @@ static u64 read_id_reg(const struct kvm_vcpu *vcpu, > /* Limit debug to ARMv8.0 */ > val &= ~FEATURE(ID_AA64DFR0_DEBUGVER); > val |= FIELD_PREP(FEATURE(ID_AA64DFR0_DEBUGVER), 6); > - /* Limit guests to PMUv3 for ARMv8.1 */ > + /* Limit guests to PMUv3 for ARMv8.4 */ > val = cpuid_feature_cap_perfmon_field(val, > ID_AA64DFR0_PMUVER_SHIFT, > - kvm_vcpu_has_pmu(vcpu) ? ID_AA64DFR0_PMUVER_8_1 : 0); > + kvm_vcpu_has_pmu(vcpu) ? ID_AA64DFR0_PMUVER_8_4 : 0); > break; > case SYS_ID_DFR0_EL1: > - /* Limit guests to PMUv3 for ARMv8.1 */ > + /* Limit guests to PMUv3 for ARMv8.4 */ > val = cpuid_feature_cap_perfmon_field(val, > ID_DFR0_PERFMON_SHIFT, > - kvm_vcpu_has_pmu(vcpu) ? ID_DFR0_PERFMON_8_1 : 0); > + kvm_vcpu_has_pmu(vcpu) ? ID_DFR0_PERFMON_8_4 : 0); > break; > } > > @@ -1496,6 +1496,7 @@ static const struct sys_reg_desc sys_reg_descs[] = { > > { SYS_DESC(SYS_PMINTENSET_EL1), access_pminten, reset_unknown, PMINTENSET_EL1 }, > { SYS_DESC(SYS_PMINTENCLR_EL1), access_pminten, reset_unknown, PMINTENSET_EL1 }, > + { SYS_DESC(SYS_PMMIR_EL1), trap_raz_wi }, > > { SYS_DESC(SYS_MAIR_EL1), access_vm_reg, reset_unknown, MAIR_EL1 }, > { SYS_DESC(SYS_AMAIR_EL1), access_vm_reg, reset_amair_el1, AMAIR_EL1 }, > @@ -1918,6 +1919,8 @@ static const struct sys_reg_desc cp15_regs[] = { > { Op1( 0), CRn( 9), CRm(14), Op2( 3), access_pmovs }, > { AA32(HI), Op1( 0), CRn( 9), CRm(14), Op2( 4), access_pmceid }, > { AA32(HI), Op1( 0), CRn( 9), CRm(14), Op2( 5), access_pmceid }, > + /* PMMIR */ > + { Op1( 0), CRn( 9), CRm(14), Op2( 6), trap_raz_wi }, > > /* PRRR/MAIR0 */ > { AA32(LO), Op1( 0), CRn(10), CRm( 2), Op2( 0), access_vm_reg, NULL, MAIR_EL1 }, _______________________________________________ kvmarm mailing list kvmarm@lists.cs.columbia.edu https://lists.cs.columbia.edu/mailman/listinfo/kvmarm