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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id E68A7C54EBE for ; Wed, 11 Jan 2023 07:55:22 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230074AbjAKHzU (ORCPT ); Wed, 11 Jan 2023 02:55:20 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56844 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231695AbjAKHzQ (ORCPT ); Wed, 11 Jan 2023 02:55:16 -0500 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 6B8A4B81 for ; Tue, 10 Jan 2023 23:55:15 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id C6C9261AB0 for ; Wed, 11 Jan 2023 07:55:14 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 238F3C433D2; Wed, 11 Jan 2023 07:55:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1673423714; bh=tnGi+atUr5f3GgeVejus72y2B1M8V5xJsa+PyZ5XD3I=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=LfE9uis7+GD5kcLB9KWv6zT4N2R0/r0F+D75Cq5EOs0NasjESEQ+1+sO9B3nfrDti V29PZZDzryAaTHMw7MfOVrwYKlWkKELHIm3NthNqL4bkcTTLxWVDVJow+9F6yFnVuW Peo028/gDC2WoKqtHgteZ4hfKuglZEgQribrVsqNKbM43AvmG1HU5VQl0wxekmJAx1 fvV/zBtx0Rhc7B64v9HnmvswL21lz+HmNFu6Hnsn+epB9ByU8OdKs+eb1BRt4Ee+7V pSoxujFhO6O8nCaL4iYAIIGXIx3KFVvCiZoNZINKDsftZCryodSttfajK6/O5SeLAA Y6pr1rV+gIswA== Received: from ip-185-104-136-29.ptr.icomera.net ([185.104.136.29] helo=wait-a-minute.misterjones.org) by disco-boy.misterjones.org with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.95) (envelope-from ) id 1pFVx1-000neJ-6q; Wed, 11 Jan 2023 07:55:11 +0000 Date: Wed, 11 Jan 2023 07:54:03 +0000 Message-ID: <87mt6pecbo.wl-maz@kernel.org> From: Marc Zyngier To: Ganapatrao Kulkarni Cc: catalin.marinas@arm.com, will@kernel.org, linux-arm-kernel@lists.infradead.org, kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org, scott@os.amperecomputing.com, Darren Hart Subject: Re: [PATCH 0/3] KVM: arm64: nv: Fixes for Nested Virtualization issues In-Reply-To: <87o7r6dpi8.wl-maz@kernel.org> References: <20220824060304.21128-1-gankulkarni@os.amperecomputing.com> <6171dc7c-5d83-d378-db9e-d94f27afe43a@os.amperecomputing.com> <87o7r6dpi8.wl-maz@kernel.org> User-Agent: Wanderlust/2.15.9 (Almost Unreal) SEMI-EPG/1.14.7 (Harue) FLIM-LB/1.14.9 (=?UTF-8?B?R29qxY0=?=) APEL-LB/10.8 EasyPG/1.0.0 Emacs/27.1 (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: 185.104.136.29 X-SA-Exim-Rcpt-To: gankulkarni@os.amperecomputing.com, catalin.marinas@arm.com, will@kernel.org, linux-arm-kernel@lists.infradead.org, kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org, scott@os.amperecomputing.com, darren@os.amperecomputing.com X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on disco-boy.misterjones.org); SAEximRunCond expanded to false Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On Tue, 10 Jan 2023 21:54:39 +0000, Marc Zyngier wrote: > > On Tue, 10 Jan 2023 12:17:20 +0000, > Ganapatrao Kulkarni wrote: > > > > I am currently working around this with "nohlt" kernel param to > > NestedVM. Any suggestions to handle/fix this case/issue and avoid the > > slowness of booting of NestedVM with more cores? > > > > Note: Guest-Hypervisor and NestedVM are using default kernel installed > > using Fedora 36 iso. > > Despite what I said earlier, I have a vague idea here, thanks to the > interesting call traces that you provided (this is really awesome work > BTW, given how hard it is to trace things across 3 different kernels). > > We can slightly limit the impact of the prepare/finish sequence if the > guest hypervisor only accesses the active registers for SGIs/PPIs on > the vcpu that owns them, forbidding any cross-CPU-to-redistributor > access. > > Something along these lines, which is only boot-tested. Let me know > how this fares for you. > > Thanks, > > M. > > diff --git a/arch/arm64/kvm/vgic/vgic-mmio.c b/arch/arm64/kvm/vgic/vgic-mmio.c > index b32d434c1d4a..1cca45be5335 100644 > --- a/arch/arm64/kvm/vgic/vgic-mmio.c > +++ b/arch/arm64/kvm/vgic/vgic-mmio.c > @@ -473,9 +473,10 @@ int vgic_uaccess_write_cpending(struct kvm_vcpu *vcpu, > * active state can be overwritten when the VCPU's state is synced coming back > * from the guest. > * > - * For shared interrupts as well as GICv3 private interrupts, we have to > - * stop all the VCPUs because interrupts can be migrated while we don't hold > - * the IRQ locks and we don't want to be chasing moving targets. > + * For shared interrupts as well as GICv3 private interrupts accessed from the > + * non-owning CPU, we have to stop all the VCPUs because interrupts can be > + * migrated while we don't hold the IRQ locks and we don't want to be chasing > + * moving targets. > * > * For GICv2 private interrupts we don't have to do anything because > * userspace accesses to the VGIC state already require all VCPUs to be > @@ -484,7 +485,8 @@ int vgic_uaccess_write_cpending(struct kvm_vcpu *vcpu, > */ > static void vgic_access_active_prepare(struct kvm_vcpu *vcpu, u32 intid) > { > - if (vcpu->kvm->arch.vgic.vgic_model == KVM_DEV_TYPE_ARM_VGIC_V3 || > + if ((vcpu->kvm->arch.vgic.vgic_model == KVM_DEV_TYPE_ARM_VGIC_V3 && > + vcpu == kvm_get_running_vcpu()) || This should obviously be + vcpu != kvm_get_running_vcpu()) || > intid >= VGIC_NR_PRIVATE_IRQS) > kvm_arm_halt_guest(vcpu->kvm); > } > @@ -492,7 +494,8 @@ static void vgic_access_active_prepare(struct kvm_vcpu *vcpu, u32 intid) > /* See vgic_access_active_prepare */ > static void vgic_access_active_finish(struct kvm_vcpu *vcpu, u32 intid) > { > - if (vcpu->kvm->arch.vgic.vgic_model == KVM_DEV_TYPE_ARM_VGIC_V3 || > + if ((vcpu->kvm->arch.vgic.vgic_model == KVM_DEV_TYPE_ARM_VGIC_V3 && > + vcpu == kvm_get_running_vcpu()) || Same here. > intid >= VGIC_NR_PRIVATE_IRQS) > kvm_arm_resume_guest(vcpu->kvm); > } Thanks, M. -- Without deviation from the norm, progress is not possible.