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 67751C433F5 for ; Mon, 2 May 2022 17:13:31 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1386600AbiEBRQ6 (ORCPT ); Mon, 2 May 2022 13:16:58 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56284 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1386593AbiEBRQ4 (ORCPT ); Mon, 2 May 2022 13:16:56 -0400 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id D3F94627B for ; Mon, 2 May 2022 10:13:26 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1651511606; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=7vf4sT7dDfJ18mM5fdZ4gMEt5hbjvc3fPcu9zyp1RQg=; b=YXiyMbisp992Bn58rpqbsBFwaIXoRYoPvX4m1fNM5B15meNnDnRYTUaxACoWNy1tI8hwc5 wtqiY3fgWNwEJvAnF8uEnoCiE8vttQkLWDYUsOSnRr6YyX7AalWTqioLdd5CAjJhf90rA2 H9fXLFdNWQ1t0d/dSxLFGfj0wFnkspI= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-277-KvGehVF_Pf2MdwaAFs1QEA-1; Mon, 02 May 2022 13:13:23 -0400 X-MC-Unique: KvGehVF_Pf2MdwaAFs1QEA-1 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.rdu2.redhat.com [10.11.54.1]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 67CA7801210; Mon, 2 May 2022 17:13:22 +0000 (UTC) Received: from starship (unknown [10.40.192.26]) by smtp.corp.redhat.com (Postfix) with ESMTP id 5216440E7F06; Mon, 2 May 2022 17:13:20 +0000 (UTC) Message-ID: <24b74f5bd8810c7f79777ed6898baeaf47bfe3e3.camel@redhat.com> Subject: Re: [PATCH v2 08/12] KVM: SVM: Update AVIC settings when changing APIC mode From: Maxim Levitsky To: Suravee Suthikulpanit , linux-kernel@vger.kernel.org, kvm@vger.kernel.org Cc: pbonzini@redhat.com, seanjc@google.com, joro@8bytes.org, jon.grimm@amd.com, wei.huang2@amd.com, terry.bowman@amd.com Date: Mon, 02 May 2022 20:13:19 +0300 In-Reply-To: <9307c734-3473-0bdc-57be-c39e96bca4d8@amd.com> References: <20220412115822.14351-1-suravee.suthikulpanit@amd.com> <20220412115822.14351-9-suravee.suthikulpanit@amd.com> <9307c734-3473-0bdc-57be-c39e96bca4d8@amd.com> Content-Type: text/plain; charset="UTF-8" User-Agent: Evolution 3.36.5 (3.36.5-2.fc32) MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.84 on 10.11.54.1 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 2022-05-02 at 21:07 +0700, Suravee Suthikulpanit wrote: > Maxim, Sean > > On 4/18/22 7:55 PM, Maxim Levitsky wrote: > > On Tue, 2022-04-12 at 06:58 -0500, Suravee Suthikulpanit wrote: > > > When APIC mode is updated (e.g. disabled, xAPIC, or x2APIC), > > > KVM needs to call kvm_vcpu_update_apicv() to update AVIC settings > > > accordingly. > > > > > > Signed-off-by: Suravee Suthikulpanit > > > --- > > > arch/x86/kvm/svm/avic.c | 15 +++++++++++++++ > > > arch/x86/kvm/svm/svm.c | 1 + > > > 2 files changed, 16 insertions(+) > > > > > > diff --git a/arch/x86/kvm/svm/avic.c b/arch/x86/kvm/svm/avic.c > > > index 22ee1098e2a5..01392b8364f4 100644 > > > --- a/arch/x86/kvm/svm/avic.c > > > +++ b/arch/x86/kvm/svm/avic.c > > > @@ -616,6 +616,21 @@ void avic_apicv_post_state_restore(struct kvm_vcpu *vcpu) > > > avic_handle_ldr_update(vcpu); > > > } > > > > > > +void avic_set_virtual_apic_mode(struct kvm_vcpu *vcpu) > > > +{ > > > + struct vcpu_svm *svm = to_svm(vcpu); > > > + > > > + if (!lapic_in_kernel(vcpu) || (avic_mode == AVIC_MODE_NONE)) > > > + return; > > > + > > > + if (kvm_get_apic_mode(vcpu) == LAPIC_MODE_INVALID) { > > > + WARN_ONCE(true, "Invalid local APIC state (vcpu_id=%d)", vcpu->vcpu_id); > > > + return; > > > + } > > > + > > > + kvm_vcpu_update_apicv(&svm->vcpu); > > I think it makes sense to call avic_refresh_apicv_exec_ctrl directly here. > > > > I am not sure that kvm_vcpu_update_apicv will even call it > > because it has an optimization of doing nothing when inhibition status > > didn't change. > > > > > > Another semi-related note: > > > > the current way the x2avic msrs are configured creates slight performance > > problem for nesting: > > > > The problem is that when entering a nested guest, AVIC on the current vCPU > > is inhibited, but this is done only so that this vCPU*peers* don't > > try to use AVIC to send IPIs to it, so there is no need to update vmcb01 > > msr interception bitmap, and vmcb02 should have all these msrs intercepted always. > > Same with returning to host. > > > > It also should be checked that during nested entry, at least vmcb01 msr bitmap > > is updated - TL;DR - please check that x2avic works when there is a nested guest running. > > In the kvm/queue branch, I found a regression on nested SVM guest, where L2 guest cannot > launch. The bad commit is: > > commit a4cfff3f0f8c07f1f7873a82bdeb3995807dac8c (bisect) > Merge: 42dcbe7d8bac 8d5678a76689 > Author: Paolo Bonzini > Date: Fri Apr 8 12:43:40 2022 -0400 > > Merge branch 'kvm-older-features' into HEAD > > Merge branch for features that did not make it into 5.18: > > * New ioctls to get/set TSC frequency for a whole VM > > * Allow userspace to opt out of hypercall patching > > Nested virtualization improvements for AMD: > > * Support for "nested nested" optimizations (nested vVMLOAD/VMSAVE, > nested vGIF) > > * Allow AVIC to co-exist with a nested guest running > > * Fixes for LBR virtualizations when a nested guest is running, > and nested LBR virtualization support > > * PAUSE filtering for nested hypervisors > > Guest support: > > * Decoupling of vcpu_is_preempted from PV spinlocks > > Signed-off-by: Paolo Bonzini > > I am still working on the bisect into the merge commits. > > Regards, > Suravee > What happens when the guest can't launch? It sure works for me for kvm/queue from yesterday. I'll test again tomorrow. Best regards, Maxim Levitsky