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 DAA45C433EF for ; Tue, 8 Feb 2022 11:55:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1356154AbiBHLzu (ORCPT ); Tue, 8 Feb 2022 06:55:50 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45084 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1356697AbiBHLzn (ORCPT ); Tue, 8 Feb 2022 06:55:43 -0500 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 DB6E2C03FECA for ; Tue, 8 Feb 2022 03:55:42 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1644321342; 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=CrvvLV6pJtPHCmu67NLbQwinnrYKaoWgfpouCR5Xtw0=; b=VsFN/hX3Xl6nQTIYCI7fR0zpulOBtUMbCNbCEMMLyauRazxDRyI0+YUHPPYAcxa8pv8xVK 6xm4OShHg4dcn2+1j9rC0cMVnCfMwXB3XCOgXpkuh5BE2iNIqmbXlBlN3HqborX2aZg491 N6imfDtbkQ7RhqOaj5yRoCod2GfQnz0= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-459-FDBsLofiMVuJy2ja0QKZ6g-1; Tue, 08 Feb 2022 06:55:37 -0500 X-MC-Unique: FDBsLofiMVuJy2ja0QKZ6g-1 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 47D0C1091DA5; Tue, 8 Feb 2022 11:55:31 +0000 (UTC) Received: from starship (unknown [10.40.192.15]) by smtp.corp.redhat.com (Postfix) with ESMTP id 529196E1EA; Tue, 8 Feb 2022 11:55:08 +0000 (UTC) Message-ID: <0c20990f2543413f4a087b7918cff14db48bc774.camel@redhat.com> Subject: Re: [PATCH RESEND 07/30] KVM: x86: nSVM: deal with L1 hypervisor that intercepts interrupts but lets L2 control them From: Maxim Levitsky To: Paolo Bonzini , kvm@vger.kernel.org Cc: Tony Luck , "Chang S. Bae" , Thomas Gleixner , Wanpeng Li , Ingo Molnar , Vitaly Kuznetsov , Pawan Gupta , Dave Hansen , linux-kernel@vger.kernel.org, Rodrigo Vivi , "H. Peter Anvin" , intel-gvt-dev@lists.freedesktop.org, Joonas Lahtinen , Joerg Roedel , Sean Christopherson , David Airlie , Zhi Wang , Brijesh Singh , Jim Mattson , x86@kernel.org, Daniel Vetter , Borislav Petkov , Zhenyu Wang , Kan Liang , Jani Nikula Date: Tue, 08 Feb 2022 13:55:07 +0200 In-Reply-To: References: <20220207155447.840194-1-mlevitsk@redhat.com> <20220207155447.840194-8-mlevitsk@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 2.79 on 10.5.11.11 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 2022-02-08 at 12:33 +0100, Paolo Bonzini wrote: > On 2/7/22 16:54, Maxim Levitsky wrote: > > Fix a corner case in which the L1 hypervisor intercepts > > interrupts (INTERCEPT_INTR) and either doesn't set > > virtual interrupt masking (V_INTR_MASKING) or enters a > > nested guest with EFLAGS.IF disabled prior to the entry. > > > > In this case, despite the fact that L1 intercepts the interrupts, > > KVM still needs to set up an interrupt window to wait before > > injecting the INTR vmexit. > > > > Currently the KVM instead enters an endless loop of 'req_immediate_exit'. > > > > Exactly the same issue also happens for SMIs and NMI. > > Fix this as well. > > > > Note that on VMX, this case is impossible as there is only > > 'vmexit on external interrupts' execution control which either set, > > in which case both host and guest's EFLAGS.IF > > are ignored, or not set, in which case no VMexits are delivered. > > > > Signed-off-by: Maxim Levitsky > > --- > > arch/x86/kvm/svm/svm.c | 17 +++++++++++++---- > > 1 file changed, 13 insertions(+), 4 deletions(-) > > > > diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c > > index 9a4e299ed5673..22e614008cf59 100644 > > --- a/arch/x86/kvm/svm/svm.c > > +++ b/arch/x86/kvm/svm/svm.c > > @@ -3372,11 +3372,13 @@ static int svm_nmi_allowed(struct kvm_vcpu *vcpu, bool for_injection) > > if (svm->nested.nested_run_pending) > > return -EBUSY; > > > > + if (svm_nmi_blocked(vcpu)) > > + return 0; > > + > > /* An NMI must not be injected into L2 if it's supposed to VM-Exit. */ > > if (for_injection && is_guest_mode(vcpu) && nested_exit_on_nmi(svm)) > > return -EBUSY; > > - > > - return !svm_nmi_blocked(vcpu); > > + return 1; > > } > > > > static bool svm_get_nmi_mask(struct kvm_vcpu *vcpu) > > @@ -3428,9 +3430,13 @@ bool svm_interrupt_blocked(struct kvm_vcpu *vcpu) > > static int svm_interrupt_allowed(struct kvm_vcpu *vcpu, bool for_injection) > > { > > struct vcpu_svm *svm = to_svm(vcpu); > > + > > if (svm->nested.nested_run_pending) > > return -EBUSY; > > > > + if (svm_interrupt_blocked(vcpu)) > > + return 0; > > + > > /* > > * An IRQ must not be injected into L2 if it's supposed to VM-Exit, > > * e.g. if the IRQ arrived asynchronously after checking nested events. > > @@ -3438,7 +3444,7 @@ static int svm_interrupt_allowed(struct kvm_vcpu *vcpu, bool for_injection) > > if (for_injection && is_guest_mode(vcpu) && nested_exit_on_intr(svm)) > > return -EBUSY; > > > > - return !svm_interrupt_blocked(vcpu); > > + return 1; > > } > > > > static void svm_enable_irq_window(struct kvm_vcpu *vcpu) > > @@ -4169,11 +4175,14 @@ static int svm_smi_allowed(struct kvm_vcpu *vcpu, bool for_injection) > > if (svm->nested.nested_run_pending) > > return -EBUSY; > > > > + if (svm_smi_blocked(vcpu)) > > + return 0; > > + > > /* An SMI must not be injected into L2 if it's supposed to VM-Exit. */ > > if (for_injection && is_guest_mode(vcpu) && nested_exit_on_smi(svm)) > > return -EBUSY; > > > > - return !svm_smi_blocked(vcpu); > > + return 1; > > } > > > > static int svm_enter_smm(struct kvm_vcpu *vcpu, char *smstate) > > Can you prepare a testcase for at least the interrupt case? Yep, I already wrote a kvm unit tests for all the cases, and I will send them very soon. Best regards, Maxim Levitsky > > Thanks, > > Paolo >