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 1AD47C4332F for ; Wed, 18 May 2022 12:47:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237373AbiERMr1 (ORCPT ); Wed, 18 May 2022 08:47:27 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42824 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S238498AbiERMrR (ORCPT ); Wed, 18 May 2022 08:47:17 -0400 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id DCFD41BDAC6 for ; Wed, 18 May 2022 05:45:36 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1652877931; 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=Q7e2eynh2lki6aaMuNiuQ3yDCBpivZWLlTQmPRG6dxE=; b=RffSnrpAkoT3RDMNovoGaSPCyEst4bv1oEV79VAX4xI8Y6+4saznV36/jhQM+lf57AEwJY KdBSynuK1LDaO5do94qRlu0VKnwQfMQT/Xp/nM0pVzTyh1qxEgPkjL4ARCAxGGGOeGrWZI tZ9VI0BWEtQ2xREIV9AWFVYpHj0CRWw= 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-656-cnRowkt-PIydbbyHKJWn5A-1; Wed, 18 May 2022 08:45:24 -0400 X-MC-Unique: cnRowkt-PIydbbyHKJWn5A-1 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.rdu2.redhat.com [10.11.54.2]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 996B9100DDF4; Wed, 18 May 2022 12:45:23 +0000 (UTC) Received: from starship (unknown [10.40.192.55]) by smtp.corp.redhat.com (Postfix) with ESMTP id 609EA4010E4E; Wed, 18 May 2022 12:45:21 +0000 (UTC) Message-ID: Subject: Re: [PATCH v3 13/34] KVM: nSVM: Keep track of Hyper-V hv_vm_id/hv_vp_id From: Maxim Levitsky To: Vitaly Kuznetsov , kvm@vger.kernel.org, Paolo Bonzini Cc: Sean Christopherson , Wanpeng Li , Jim Mattson , Michael Kelley , Siddharth Chandrasekaran , linux-hyperv@vger.kernel.org, linux-kernel@vger.kernel.org Date: Wed, 18 May 2022 15:45:20 +0300 In-Reply-To: <874k1nuiw8.fsf@redhat.com> References: <20220414132013.1588929-1-vkuznets@redhat.com> <20220414132013.1588929-14-vkuznets@redhat.com> <30b0e63c0a2d3c3c40edb47af6d80e452f1e69fa.camel@redhat.com> <874k1nuiw8.fsf@redhat.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 10.11.54.2 Precedence: bulk List-ID: X-Mailing-List: linux-hyperv@vger.kernel.org On Wed, 2022-05-18 at 14:25 +0200, Vitaly Kuznetsov wrote: > Maxim Levitsky writes: > > > On Thu, 2022-04-14 at 15:19 +0200, Vitaly Kuznetsov wrote: > > > Similar to nSVM, KVM needs to know L2's VM_ID/VP_ID and Partition > > > assist page address to handle L2 TLB flush requests. > > > > > > Signed-off-by: Vitaly Kuznetsov > > > --- > > > arch/x86/kvm/svm/hyperv.h | 16 ++++++++++++++++ > > > arch/x86/kvm/svm/nested.c | 2 ++ > > > 2 files changed, 18 insertions(+) > > > > > > diff --git a/arch/x86/kvm/svm/hyperv.h b/arch/x86/kvm/svm/hyperv.h > > > index 7d6d97968fb9..8cf702fed7e5 100644 > > > --- a/arch/x86/kvm/svm/hyperv.h > > > +++ b/arch/x86/kvm/svm/hyperv.h > > > @@ -9,6 +9,7 @@ > > > #include > > > > > > #include "../hyperv.h" > > > +#include "svm.h" > > > > > > /* > > > * Hyper-V uses the software reserved 32 bytes in VMCB > > > @@ -32,4 +33,19 @@ struct hv_enlightenments { > > > */ > > > #define VMCB_HV_NESTED_ENLIGHTENMENTS VMCB_SW > > > > > > +static inline void nested_svm_hv_update_vm_vp_ids(struct kvm_vcpu *vcpu) > > > +{ > > > + struct vcpu_svm *svm = to_svm(vcpu); > > > + struct hv_enlightenments *hve = > > > + (struct hv_enlightenments *)svm->nested.ctl.reserved_sw; > > > > Small nitpick: > > > > Can we use this as an opportunity to rename the 'reserved_sw' to \ > > 'hv_enlightenments' or something, because that is what it is? > > > > Also the reserved_sw is an array, which is confusing, since from first look, > > it looks like we have a pointer dereference here. > > > > Well, that's what it is in Hyper-V world and so far we didn't give it > another meaning in KVM but in theory it is not impossible, e.g. we can > use this area to speed up nested KVM on KVM. > > AMD calls this "Reserved for Host usage" so we can probably rename it to > 'reserved_host' but I'm not sure it's worth the hassle... This is a very good piece of information. If AMD calls it like that, than let it be. It is probably not worth it to rename the field then, but I think it is might be worth it to add this info as a comment to the KVM. Also it might be worth it to add some wrapper function for 'struct hv_enlightenments *hve = (struct hv_enlightenments *)svm->nested.ctl.reserved_sw;' (+ check if this area is valid - currently it is copied only when 'kvm_hv_hypercall_enabled == true'). Both would be a very low priority items to be honest. Thanks, Best regards, MaxiMm Levitsky > > > > > > + struct kvm_vcpu_hv *hv_vcpu = to_hv_vcpu(vcpu); > > > + > > > + if (!hv_vcpu) > > > + return; > > > + > > > + hv_vcpu->nested.pa_page_gpa = hve->partition_assist_page; > > > + hv_vcpu->nested.vm_id = hve->hv_vm_id; > > > + hv_vcpu->nested.vp_id = hve->hv_vp_id; > > > +} > > > + > > > #endif /* __ARCH_X86_KVM_SVM_HYPERV_H__ */ > > > diff --git a/arch/x86/kvm/svm/nested.c b/arch/x86/kvm/svm/nested.c > > > index bed5e1692cef..2d1a76343404 100644 > > > --- a/arch/x86/kvm/svm/nested.c > > > +++ b/arch/x86/kvm/svm/nested.c > > > @@ -826,6 +826,8 @@ int nested_svm_vmrun(struct kvm_vcpu *vcpu) > > > > > > svm->nested.nested_run_pending = 1; > > > > > > + nested_svm_hv_update_vm_vp_ids(vcpu); > > > + > > > if (enter_svm_guest_mode(vcpu, vmcb12_gpa, vmcb12, true)) > > > goto out_exit_err; > > > > > > > That won't work after migration, since this won't be called > > if we migrate with nested guest running. > > > > > > I think that nested_svm_hv_update_vm_vp_ids should be called > > from enter_svm_guest_mode. > > > > Oh that's a good one, thanks! This could've been a hard to debug issue. >