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 9D31EC25B07 for ; Fri, 5 Aug 2022 18:37:22 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237209AbiHEShV (ORCPT ); Fri, 5 Aug 2022 14:37:21 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40126 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S241225AbiHEShT (ORCPT ); Fri, 5 Aug 2022 14:37:19 -0400 Received: from mail-pf1-x42d.google.com (mail-pf1-x42d.google.com [IPv6:2607:f8b0:4864:20::42d]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 516D2EE2C for ; Fri, 5 Aug 2022 11:37:18 -0700 (PDT) Received: by mail-pf1-x42d.google.com with SMTP id q19so2947586pfg.8 for ; Fri, 05 Aug 2022 11:37:18 -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=lELyiIs1M4XhaXsTw4w5NqfKv5uqGU1KMVAeFBFrmLw=; b=IjSOTskopD9xhiXK61Q0+jIYrE1wEloCdlU8aKJFpxNmGh4dk0tEyWp8tiKqoAH9S/ vfWt5HGfLWgwGo0iuRY1BHR0J5VSYzv85H9DvcVdXGdiqUhmxLyU7r5IdEYP247TdcGY PgogGFR/bHG35vakLhyyIOaHbTbVsxHDPcsi70s342ctBmpme/sQQORnmeln6LjFnUaS i91Whc6wvegRSfOiXyNrHvONBZm+q7SVhaRLQmNHA9VN49Gc7JaIL8eknoDE80Ausndf ZWUZU+XceH3clbGQghM592Uh7sYRu5a+pYvh1DHyFjF3YVkzgl8CO9fEeJw982UUMZdA Fx6A== 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=lELyiIs1M4XhaXsTw4w5NqfKv5uqGU1KMVAeFBFrmLw=; b=MBjaw6OYR6oszm3MwdtVY+uapVnLzoBCL8iCEn1efkmUfMgbHQLjW+leImkqOzc0S5 0tYAqDqw0Jub/DRITBCwaDzM/xu6n8JOiFPBNinFRf1KInmMJklS6puBsx/g94xgSCkT k5MCy61SNIqiegUNY3vmMLIC68BT4xwfsWxYkHCJqwOl3Ywu+D9YtajUlnzAnmS0uHUz anigcJzkW+0UkGAWNF5M2R6sC4HjObFq+1ahcB4+3CLFAtPABmXkCcg2Usx8kIXg0VW5 Net7rY6CWF2y+gp1jHknnDGVmOTWLkwP/ly1lAM5CfTYV7gTXikZF7iBAxMurIB8qZ+b BecQ== X-Gm-Message-State: ACgBeo02kQCdFCVGQYZdjBzC2fIvNiVI97YnsjWr69merSHhmBYk8r8m hbxfMHiuLqBEirdfpo/WF9xs0g== X-Google-Smtp-Source: AA6agR5uK/vVHvtkmvHFgUqgHizAXSnbLOqsLz1hkP/xNbxDCwRqyr+pfYvuuGfxHn/o2dsOXdYKvg== X-Received: by 2002:a63:4645:0:b0:41a:6c24:4fa3 with SMTP id v5-20020a634645000000b0041a6c244fa3mr6892782pgk.114.1659724637580; Fri, 05 Aug 2022 11:37:17 -0700 (PDT) Received: from google.com (7.104.168.34.bc.googleusercontent.com. [34.168.104.7]) by smtp.gmail.com with ESMTPSA id t67-20020a628146000000b0052d8b663c37sm3288244pfd.195.2022.08.05.11.37.17 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 05 Aug 2022 11:37:17 -0700 (PDT) Date: Fri, 5 Aug 2022 18:37:13 +0000 From: Sean Christopherson To: Coleman Dietsch Cc: kvm@vger.kernel.org, Paolo Bonzini , 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, syzbot+e54f930ed78eb0f85281@syzkaller.appspotmail.com Subject: Re: [PATCH v2 1/2] KVM: x86/xen: Initialize Xen timer only once Message-ID: References: <20220729184640.244969-1-dietschc@csp.edu> <20220729184640.244969-2-dietschc@csp.edu> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220729184640.244969-2-dietschc@csp.edu> Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On Fri, Jul 29, 2022, Coleman Dietsch wrote: > Add a check for existing xen timers before initializing a new one. > > Currently kvm_xen_init_timer() is called on every > KVM_XEN_VCPU_ATTR_TYPE_TIMER, which is causing the following ODEBUG > crash when vcpu->arch.xen.timer is already set. > > ODEBUG: init active (active state 0) > object type: hrtimer hint: xen_timer_callbac0 > RIP: 0010:debug_print_object+0x16e/0x250 lib/debugobjects.c:502 > Call Trace: > __debug_object_init > debug_hrtimer_init > debug_init > hrtimer_init > kvm_xen_init_timer > kvm_xen_vcpu_set_attr > kvm_arch_vcpu_ioctl > kvm_vcpu_ioctl > vfs_ioctl > Fixes: 536395260582 ("KVM: x86/xen: handle PV timers oneshot mode") Cc: stable@vger.kernel.org > Link: https://syzkaller.appspot.com/bug?id=8234a9dfd3aafbf092cc5a7cd9842e3ebc45fc42 > Reported-by: syzbot+e54f930ed78eb0f85281@syzkaller.appspotmail.com > Signed-off-by: Coleman Dietsch > --- One uber nit below, otherwise: Reviewed-by: Sean Christopherson > arch/x86/kvm/xen.c | 5 ++++- > 1 file changed, 4 insertions(+), 1 deletion(-) > > diff --git a/arch/x86/kvm/xen.c b/arch/x86/kvm/xen.c > index 610beba35907..2dd0f72a62f2 100644 > --- a/arch/x86/kvm/xen.c > +++ b/arch/x86/kvm/xen.c > @@ -713,7 +713,10 @@ int kvm_xen_vcpu_set_attr(struct kvm_vcpu *vcpu, struct kvm_xen_vcpu_attr *data) > break; > } > vcpu->arch.xen.timer_virq = data->u.timer.port; > - kvm_xen_init_timer(vcpu); > + > + /* Check for existing timer */ I vote to omit the comment, "existing timer" is ambiguous, e.g. it could mean that there's an existing _running_ timer as opposed to an existing initialized timer. IMO the code is obvious enough on its own. > + if (!vcpu->arch.xen.timer.function) > + kvm_xen_init_timer(vcpu); > > /* Restart the timer if it's set */ > if (data->u.timer.expires_ns) > -- > 2.34.1 >