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 BF06AC19F2D for ; Tue, 9 Aug 2022 14:40:58 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S243764AbiHIOkg (ORCPT ); Tue, 9 Aug 2022 10:40:36 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59496 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S243757AbiHIOke (ORCPT ); Tue, 9 Aug 2022 10:40:34 -0400 Received: from mail-pj1-x102b.google.com (mail-pj1-x102b.google.com [IPv6:2607:f8b0:4864:20::102b]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 24C13273F for ; Tue, 9 Aug 2022 07:40:33 -0700 (PDT) Received: by mail-pj1-x102b.google.com with SMTP id e8-20020a17090a280800b001f2fef7886eso12379478pjd.3 for ; Tue, 09 Aug 2022 07:40:33 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:from:to:cc; bh=OdbOjGUjW12bCfbeWBjGSJ1Nu6Rk3c5Ky+ZI53W01wg=; b=TaXG+ej0jDZE0fRN4noaJtSFB5ltkCHj7OE6Qr0NL5hSpQhtaKSX0RdDRHiXlYQdy7 MSEMDDxfpGEWa+w6jBWpVEwFG41oOAiq602dOmmdikaoW+Jsupla/nPEcG2Wug4G8QeI R/6wu3IwfV1cXrxn1hb2o5uHm34Q7XMdvKznNBglR8Vqp2fkXdJwB9/T97p/P5tbfJC2 iJC6RTuGl32t6ZBKATAv6goAxQVAAVbtv3vsIH6qp290lpHClC8dvzuVSIkWK6lUJDt0 ctBxtIYfoWBW7cm+VQpAFbdsgBentT5METMZgPILhQltDG0Q34WrrfR8jy3B1NmYNvwD EmWw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-message-state:from:to:cc; bh=OdbOjGUjW12bCfbeWBjGSJ1Nu6Rk3c5Ky+ZI53W01wg=; b=4fSt0azIrWKoBSxWR+xAPkRec4Ae6iTDMHugL+HEO2pMEW6M2xsyG66SEo8Cu55cL8 gHpV1YIaWdm+Q2IXzvi9KePC4qKzNFh7t7Bq75JwGo/Kn0DkJSa//QxPJhLTGCWn0Rrp EHwIxvV7Bk7lw4cte7pT0lBNNU0HZkRYEnwq7rf/FcLyCx6/oCmFwiUuV+eQYfnUebbV RhNOd/5AV8S61r2YLAWTnoDNTmQRHJwBh0irgjF0vOu+Fr9NR98On4HZvDvkifYelor5 aoh2noLI/CgqO279qx0H9P6UNxP/A2lkx+MFwwsUWem3Ws7i7mf4CoqbObeQg9b/Ih0V 3T4A== X-Gm-Message-State: ACgBeo34nXAJxnR+vYa1BTLJxqy+fxu0hgU7C1G8l2Y6tIpyi7QW/Ydi /h0tmLEKPPeDCL6VM4AgLpWVVQ== X-Google-Smtp-Source: AA6agR5dJBGAgBiZdySMn0shi1wg9/jp8sdMtEe28i2vcg1gxytljbDTOA1J7khCTdbdWwzUz3C3pA== X-Received: by 2002:a17:903:22c1:b0:16f:3d1:f5c with SMTP id y1-20020a17090322c100b0016f03d10f5cmr23843077plg.155.1660056032526; Tue, 09 Aug 2022 07:40:32 -0700 (PDT) Received: from google.com (7.104.168.34.bc.googleusercontent.com. [34.168.104.7]) by smtp.gmail.com with ESMTPSA id q11-20020a170902dacb00b0016dcfedfe30sm11056894plx.90.2022.08.09.07.40.31 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 09 Aug 2022 07:40:31 -0700 (PDT) Date: Tue, 9 Aug 2022 14:40:28 +0000 From: Sean Christopherson To: Paolo Bonzini Cc: David Woodhouse , Coleman Dietsch , kvm@vger.kernel.org, Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org, "H . Peter Anvin" , linux-kernel@vger.kernel.org, skhan@linuxfoundation.org, Pavel Skripkin , linux-kernel-mentees@lists.linuxfoundation.org, stable@vger.kernel.org, syzbot+e54f930ed78eb0f85281@syzkaller.appspotmail.com, metikaya Subject: Re: [PATCH v3 2/2] KVM: x86/xen: Stop Xen timer before changing IRQ Message-ID: References: <20220808190607.323899-2-dietschc@csp.edu> <20220808190607.323899-3-dietschc@csp.edu> <43e258cc-71ac-bde4-d1f8-9eb9519928d3@redhat.com> <4fc1371b83001b4eed1617c37bec6b9d007e45c2.camel@infradead.org> <0b5dcab333906f166fcdbc296373cc5e08bec79f.camel@infradead.org> <953d2e99-ed1a-384d-6d3a-0f656a243f82@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <953d2e99-ed1a-384d-6d3a-0f656a243f82@redhat.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Aug 09, 2022, Paolo Bonzini wrote: > On 8/9/22 16:16, David Woodhouse wrote: > > I find the new version a bit harder to follow, with its init-then-stop- > > then-start logic: > > > > case KVM_XEN_VCPU_ATTR_TYPE_TIMER: > > if (data->u.timer.port && > > data->u.timer.priority != KVM_IRQ_ROUTING_XEN_EVTCHN_PRIO_2LEVEL) { > > r = -EINVAL; > > break; > > } > > > > if (!vcpu->arch.xen.timer.function) > > kvm_xen_init_timer(vcpu); > > > > /* Stop the timer (if it's running) before changing the vector */ > > kvm_xen_stop_timer(vcpu); > > vcpu->arch.xen.timer_virq = data->u.timer.port; > > > I think this is fine, if anything the kvm_xen_stop_timer() call could be > placed in an "else" but I'm leaning towards applying this version of the > patch. I wanted to separate the "init" from the "stop+start", e.g. if there were a more appropriate place for invoking kvm_xen_init_timer() I would have suggested moving the call outside of KVM_XEN_VCPU_ATTR_TYPE_TIMER entirely.