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=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 54706C43603 for ; Fri, 20 Dec 2019 18:08:23 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 367802082E for ; Fri, 20 Dec 2019 18:08:23 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727509AbfLTSIT (ORCPT ); Fri, 20 Dec 2019 13:08:19 -0500 Received: from foss.arm.com ([217.140.110.172]:53888 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727390AbfLTSIT (ORCPT ); Fri, 20 Dec 2019 13:08:19 -0500 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 C1D5D1FB; Fri, 20 Dec 2019 10:08:18 -0800 (PST) Received: from lakrids.cambridge.arm.com (usa-sjc-imap-foss1.foss.arm.com [10.121.207.14]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 8DC363F67D; Fri, 20 Dec 2019 10:08:17 -0800 (PST) Date: Fri, 20 Dec 2019 18:08:15 +0000 From: Mark Rutland To: Andrew Murray Cc: Marc Zyngier , Catalin Marinas , Will Deacon , Sudeep Holla , kvmarm@lists.cs.columbia.edu, linux-arm-kernel@lists.infradead.org, kvm@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2 11/18] KVM: arm64: don't trap Statistical Profiling controls to EL2 Message-ID: <20191220180815.GE25258@lakrids.cambridge.arm.com> References: <20191220143025.33853-1-andrew.murray@arm.com> <20191220143025.33853-12-andrew.murray@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20191220143025.33853-12-andrew.murray@arm.com> User-Agent: Mutt/1.11.1+11 (2f07cb52) (2018-12-01) Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On Fri, Dec 20, 2019 at 02:30:18PM +0000, Andrew Murray wrote: > As we now save/restore the profiler state there is no need to trap > accesses to the statistical profiling controls. Let's unset the > _TPMS bit. > > Signed-off-by: Andrew Murray > --- > arch/arm64/kvm/debug.c | 2 -- > 1 file changed, 2 deletions(-) > > diff --git a/arch/arm64/kvm/debug.c b/arch/arm64/kvm/debug.c > index 43487f035385..07ca783e7d9e 100644 > --- a/arch/arm64/kvm/debug.c > +++ b/arch/arm64/kvm/debug.c > @@ -88,7 +88,6 @@ void kvm_arm_reset_debug_ptr(struct kvm_vcpu *vcpu) > * - Performance monitors (MDCR_EL2_TPM/MDCR_EL2_TPMCR) > * - Debug ROM Address (MDCR_EL2_TDRA) > * - OS related registers (MDCR_EL2_TDOSA) > - * - Statistical profiler (MDCR_EL2_TPMS/MDCR_EL2_E2PB) > * > * Additionally, KVM only traps guest accesses to the debug registers if > * the guest is not actively using them (see the KVM_ARM64_DEBUG_DIRTY > @@ -111,7 +110,6 @@ void kvm_arm_setup_debug(struct kvm_vcpu *vcpu) > */ > vcpu->arch.mdcr_el2 = __this_cpu_read(mdcr_el2) & MDCR_EL2_HPMN_MASK; > vcpu->arch.mdcr_el2 |= (MDCR_EL2_TPM | > - MDCR_EL2_TPMS | > MDCR_EL2_TPMCR | > MDCR_EL2_TDRA | > MDCR_EL2_TDOSA); I think that this should be conditional on some vcpu feature flag. If nothing else, this could break existing migration cases otherwise. Thanks, Mark.