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=-7.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS 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 2FF88C04AB6 for ; Tue, 28 May 2019 08:18:28 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 0C17E20883 for ; Tue, 28 May 2019 08:18:27 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726441AbfE1IS0 (ORCPT ); Tue, 28 May 2019 04:18:26 -0400 Received: from usa-sjc-mx-foss1.foss.arm.com ([217.140.101.70]:51710 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725943AbfE1IS0 (ORCPT ); Tue, 28 May 2019 04:18:26 -0400 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.72.51.249]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id BA68C341; Tue, 28 May 2019 01:18:25 -0700 (PDT) Received: from [10.1.197.45] (e112298-lin.cambridge.arm.com [10.1.197.45]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 149EB3F59C; Tue, 28 May 2019 01:18:22 -0700 (PDT) Subject: Re: [PATCH v2 07/15] arm64: KVM: split debug save restore across vm/traps activation To: Sudeep Holla , kvmarm@lists.cs.columbia.edu, linux-arm-kernel@lists.infradead.org Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org, Christoffer Dall , Marc Zyngier , James Morse , Suzuki K Pouloze , Catalin Marinas , Will Deacon References: <20190523103502.25925-1-sudeep.holla@arm.com> <20190523103502.25925-8-sudeep.holla@arm.com> From: Julien Thierry Message-ID: <84eba64a-899f-e231-0873-c3ccfeb2201d@arm.com> Date: Tue, 28 May 2019 09:18:17 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.2.1 MIME-Version: 1.0 In-Reply-To: <20190523103502.25925-8-sudeep.holla@arm.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Sudeep, On 23/05/2019 11:34, Sudeep Holla wrote: > If we enable profiling buffer controls at EL1 generate a trap exception > to EL2, it also changes profiling buffer to use EL1&0 stage 1 translation > regime in case of VHE. To support SPE both in the guest and host, we > need to first stop profiling and flush the profiling buffers before > we activate/switch vm or enable/disable the traps. > > In prepartion to do that, lets split the debug save restore functionality > into 4 steps: > 1. debug_save_host_context - saves the host context > 2. debug_restore_guest_context - restore the guest context > 3. debug_save_guest_context - saves the guest context > 4. debug_restore_host_context - restores the host context > > Lets rename existing __debug_switch_to_{host,guest} to make sure it's > aligned to the above and just add the place holders for new ones getting > added here as we need them to support SPE in guests. > > Signed-off-by: Sudeep Holla > --- > arch/arm64/include/asm/kvm_hyp.h | 6 ++++-- > arch/arm64/kvm/hyp/debug-sr.c | 25 ++++++++++++++++--------- > arch/arm64/kvm/hyp/switch.c | 12 ++++++++---- > 3 files changed, 28 insertions(+), 15 deletions(-) > > diff --git a/arch/arm64/include/asm/kvm_hyp.h b/arch/arm64/include/asm/kvm_hyp.h > index 782955db61dd..1c5ed80fcbda 100644 > --- a/arch/arm64/include/asm/kvm_hyp.h > +++ b/arch/arm64/include/asm/kvm_hyp.h > @@ -164,8 +164,10 @@ void sysreg_restore_guest_state_vhe(struct kvm_cpu_context *ctxt); > void __sysreg32_save_state(struct kvm_vcpu *vcpu); > void __sysreg32_restore_state(struct kvm_vcpu *vcpu); > > -void __debug_switch_to_guest(struct kvm_vcpu *vcpu); > -void __debug_switch_to_host(struct kvm_vcpu *vcpu); > +void __debug_save_host_context(struct kvm_vcpu *vcpu); > +void __debug_restore_guest_context(struct kvm_vcpu *vcpu); > +void __debug_save_guest_context(struct kvm_vcpu *vcpu); > +void __debug_restore_host_context(struct kvm_vcpu *vcpu); > > void __fpsimd_save_state(struct user_fpsimd_state *fp_regs); > void __fpsimd_restore_state(struct user_fpsimd_state *fp_regs); > diff --git a/arch/arm64/kvm/hyp/debug-sr.c b/arch/arm64/kvm/hyp/debug-sr.c > index fa51236ebcb3..618884df1dc4 100644 > --- a/arch/arm64/kvm/hyp/debug-sr.c > +++ b/arch/arm64/kvm/hyp/debug-sr.c > @@ -149,20 +149,13 @@ static void __hyp_text __debug_restore_state(struct kvm_vcpu *vcpu, > write_sysreg(ctxt->sys_regs[MDCCINT_EL1], mdccint_el1); > } > > -void __hyp_text __debug_switch_to_guest(struct kvm_vcpu *vcpu) > +void __hyp_text __debug_restore_guest_context(struct kvm_vcpu *vcpu) > { > struct kvm_cpu_context *host_ctxt; > struct kvm_cpu_context *guest_ctxt; > struct kvm_guest_debug_arch *host_dbg; > struct kvm_guest_debug_arch *guest_dbg; > > - /* > - * Non-VHE: Disable and flush SPE data generation > - * VHE: The vcpu can run, but it can't hide. > - */ > - if (!has_vhe()) > - __debug_save_spe_nvhe(&vcpu->arch.host_debug_state.pmscr_el1); > - > if (!(vcpu->arch.flags & KVM_ARM64_DEBUG_DIRTY)) > return; > > @@ -175,7 +168,7 @@ void __hyp_text __debug_switch_to_guest(struct kvm_vcpu *vcpu) > __debug_restore_state(vcpu, guest_dbg, guest_ctxt); > } > > -void __hyp_text __debug_switch_to_host(struct kvm_vcpu *vcpu) > +void __hyp_text __debug_restore_host_context(struct kvm_vcpu *vcpu) In the current state of the sources, __debug_switch_to_host() seems to save the guest debug state before restoring the host's: __debug_save_state(vcpu, guest_dbg, guest_ctxt); Since you're splitting the switch_to into save/restore operations, it feels like this would fit better __debug_save_guest_context() (currently empty) rather than __debug_restore_host_context(). Cheers, -- Julien Thierry