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=-6.9 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,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 082CEC433E1 for ; Wed, 10 Jun 2020 19:32:26 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id DDD512074B for ; Wed, 10 Jun 2020 19:32:25 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="Exn7GRPa" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730178AbgFJTcW (ORCPT ); Wed, 10 Jun 2020 15:32:22 -0400 Received: from us-smtp-delivery-1.mimecast.com ([207.211.31.120]:37917 "EHLO us-smtp-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726806AbgFJTcW (ORCPT ); Wed, 10 Jun 2020 15:32:22 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1591817540; 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: in-reply-to:in-reply-to:references:references; bh=TXEO0NMuFamvlSFmJYPE6uLqbht0lTepf382LStAP+k=; b=Exn7GRPaMLh6Mi3j0QwtjgO2xOu0/BE+bG5Hf6IWp06ccsiJFnd6nM+1+u6soT5RRZLflb tKPIzmssHZ5rogwpdC9fiwFRBQo0SuP0dZ9Zop6/ZRrF14WFi36S8OHgY8NaBVuFtZj/Kd EslBfwJ5LIQcqbP0DwRZgdE/TkKWC+c= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-421--wPs3G4uPouBF9N71rymCw-1; Wed, 10 Jun 2020 15:32:15 -0400 X-MC-Unique: -wPs3G4uPouBF9N71rymCw-1 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 8E45C8018AB; Wed, 10 Jun 2020 19:32:13 +0000 (UTC) Received: from horse.redhat.com (ovpn-115-64.rdu2.redhat.com [10.10.115.64]) by smtp.corp.redhat.com (Postfix) with ESMTP id 492365D9D7; Wed, 10 Jun 2020 19:32:12 +0000 (UTC) Received: by horse.redhat.com (Postfix, from userid 10451) id C5A582205BD; Wed, 10 Jun 2020 15:32:11 -0400 (EDT) Date: Wed, 10 Jun 2020 15:32:11 -0400 From: Vivek Goyal To: Vitaly Kuznetsov Cc: kvm@vger.kernel.org, Paolo Bonzini , Sean Christopherson , Wanpeng Li , Jim Mattson , linux-kernel@vger.kernel.org Subject: Re: [PATCH 2/2] KVM: async_pf: Inject 'page ready' event only if 'page not present' was previously injected Message-ID: <20200610193211.GB243520@redhat.com> References: <20200610175532.779793-1-vkuznets@redhat.com> <20200610175532.779793-2-vkuznets@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200610175532.779793-2-vkuznets@redhat.com> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On Wed, Jun 10, 2020 at 07:55:32PM +0200, Vitaly Kuznetsov wrote: > 'Page not present' event may or may not get injected depending on > guest's state. If the event wasn't injected, there is no need to > inject the corresponding 'page ready' event as the guest may get > confused. E.g. Linux thinks that the corresponding 'page not present' > event wasn't delivered *yet* and allocates a 'dummy entry' for it. > This entry is never freed. > > Note, 'wakeup all' events have no corresponding 'page not present' > event and always get injected. > > s390 seems to always be able to inject 'page not present', the > change is effectively a nop. > > Suggested-by: Vivek Goyal > Signed-off-by: Vitaly Kuznetsov > --- > arch/s390/include/asm/kvm_host.h | 2 +- > arch/s390/kvm/kvm-s390.c | 4 +++- > arch/x86/include/asm/kvm_host.h | 2 +- > arch/x86/kvm/x86.c | 7 +++++-- > include/linux/kvm_host.h | 1 + > virt/kvm/async_pf.c | 2 +- > 6 files changed, 12 insertions(+), 6 deletions(-) > > diff --git a/arch/s390/include/asm/kvm_host.h b/arch/s390/include/asm/kvm_host.h > index 3d554887794e..cee3cb6455a2 100644 > --- a/arch/s390/include/asm/kvm_host.h > +++ b/arch/s390/include/asm/kvm_host.h > @@ -978,7 +978,7 @@ bool kvm_arch_can_dequeue_async_page_present(struct kvm_vcpu *vcpu); > void kvm_arch_async_page_ready(struct kvm_vcpu *vcpu, > struct kvm_async_pf *work); > > -void kvm_arch_async_page_not_present(struct kvm_vcpu *vcpu, > +bool kvm_arch_async_page_not_present(struct kvm_vcpu *vcpu, > struct kvm_async_pf *work); Hi Vitaly, A minor nit. Using return code to figure out if exception was injected or not is little odd. How about we pass a pointer instead as parameter and kvm_arch_async_page_not_present() sets it to true if page not present exception was injected. This probably will be easier to read. If for some reason you don't like above, atleats it warrants a comment explaining what do 0 and 1 mean. Otherwise both the patches look good to me. I tested and I can confirm that now page ready events are not being delivered to guest if page not present was not injected. Thanks Vivek > > void kvm_arch_async_page_present(struct kvm_vcpu *vcpu, > diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c > index 06bde4bad205..33fea4488ef3 100644 > --- a/arch/s390/kvm/kvm-s390.c > +++ b/arch/s390/kvm/kvm-s390.c > @@ -3923,11 +3923,13 @@ static void __kvm_inject_pfault_token(struct kvm_vcpu *vcpu, bool start_token, > } > } > > -void kvm_arch_async_page_not_present(struct kvm_vcpu *vcpu, > +bool kvm_arch_async_page_not_present(struct kvm_vcpu *vcpu, > struct kvm_async_pf *work) > { > trace_kvm_s390_pfault_init(vcpu, work->arch.pfault_token); > __kvm_inject_pfault_token(vcpu, true, work->arch.pfault_token); > + > + return true; > } > > void kvm_arch_async_page_present(struct kvm_vcpu *vcpu, > diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h > index 6e03c021956a..f54e7499fc6a 100644 > --- a/arch/x86/include/asm/kvm_host.h > +++ b/arch/x86/include/asm/kvm_host.h > @@ -1660,7 +1660,7 @@ void kvm_make_scan_ioapic_request(struct kvm *kvm); > void kvm_make_scan_ioapic_request_mask(struct kvm *kvm, > unsigned long *vcpu_bitmap); > > -void kvm_arch_async_page_not_present(struct kvm_vcpu *vcpu, > +bool kvm_arch_async_page_not_present(struct kvm_vcpu *vcpu, > struct kvm_async_pf *work); > void kvm_arch_async_page_present(struct kvm_vcpu *vcpu, > struct kvm_async_pf *work); > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c > index 13d0b0fa1a7c..75e4c68e9586 100644 > --- a/arch/x86/kvm/x86.c > +++ b/arch/x86/kvm/x86.c > @@ -10513,7 +10513,7 @@ bool kvm_can_do_async_pf(struct kvm_vcpu *vcpu) > return kvm_arch_interrupt_allowed(vcpu); > } > > -void kvm_arch_async_page_not_present(struct kvm_vcpu *vcpu, > +bool kvm_arch_async_page_not_present(struct kvm_vcpu *vcpu, > struct kvm_async_pf *work) > { > struct x86_exception fault; > @@ -10530,6 +10530,7 @@ void kvm_arch_async_page_not_present(struct kvm_vcpu *vcpu, > fault.address = work->arch.token; > fault.async_page_fault = true; > kvm_inject_page_fault(vcpu, &fault); > + return true; > } else { > /* > * It is not possible to deliver a paravirtualized asynchronous > @@ -10540,6 +10541,7 @@ void kvm_arch_async_page_not_present(struct kvm_vcpu *vcpu, > * fault is retried, hopefully the page will be ready in the host. > */ > kvm_make_request(KVM_REQ_APF_HALT, vcpu); > + return false; > } > } > > @@ -10557,7 +10559,8 @@ void kvm_arch_async_page_present(struct kvm_vcpu *vcpu, > kvm_del_async_pf_gfn(vcpu, work->arch.gfn); > trace_kvm_async_pf_ready(work->arch.token, work->cr2_or_gpa); > > - if (kvm_pv_async_pf_enabled(vcpu) && > + if ((work->wakeup_all || work->notpresent_injected) && > + kvm_pv_async_pf_enabled(vcpu) && > !apf_put_user_ready(vcpu, work->arch.token)) { > vcpu->arch.apf.pageready_pending = true; > kvm_apic_set_irq(vcpu, &irq, NULL); > diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h > index 802b9e2306f0..2456dc5338f8 100644 > --- a/include/linux/kvm_host.h > +++ b/include/linux/kvm_host.h > @@ -206,6 +206,7 @@ struct kvm_async_pf { > unsigned long addr; > struct kvm_arch_async_pf arch; > bool wakeup_all; > + bool notpresent_injected; > }; > > void kvm_clear_async_pf_completion_queue(struct kvm_vcpu *vcpu); > diff --git a/virt/kvm/async_pf.c b/virt/kvm/async_pf.c > index ba080088da76..a36828fbf40a 100644 > --- a/virt/kvm/async_pf.c > +++ b/virt/kvm/async_pf.c > @@ -189,7 +189,7 @@ int kvm_setup_async_pf(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa, > > list_add_tail(&work->queue, &vcpu->async_pf.queue); > vcpu->async_pf.queued++; > - kvm_arch_async_page_not_present(vcpu, work); > + work->notpresent_injected = kvm_arch_async_page_not_present(vcpu, work); > > schedule_work(&work->work); > > -- > 2.25.4 >