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=-5.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 EFEF4C83003 for ; Wed, 29 Apr 2020 07:37:42 +0000 (UTC) Received: from lists.xenproject.org (lists.xenproject.org [192.237.175.120]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id C6EEE2073E for ; Wed, 29 Apr 2020 07:37:42 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org C6EEE2073E Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=suse.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=xen-devel-bounces@lists.xenproject.org Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1jThHZ-00057e-Bc; Wed, 29 Apr 2020 07:37:25 +0000 Received: from all-amaz-eas1.inumbo.com ([34.197.232.57] helo=us1-amaz-eas2.inumbo.com) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1jThHY-00057Z-Md for xen-devel@lists.xenproject.org; Wed, 29 Apr 2020 07:37:24 +0000 X-Inumbo-ID: 430828de-89ec-11ea-9917-12813bfff9fa Received: from mx2.suse.de (unknown [195.135.220.15]) by us1-amaz-eas2.inumbo.com (Halon) with ESMTPS id 430828de-89ec-11ea-9917-12813bfff9fa; Wed, 29 Apr 2020 07:37:22 +0000 (UTC) X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx2.suse.de (Postfix) with ESMTP id 180B7AF5C; Wed, 29 Apr 2020 07:37:20 +0000 (UTC) Subject: Re: [PATCH] x86/pass-through: avoid double IRQ unbind during domain cleanup To: =?UTF-8?Q?Roger_Pau_Monn=c3=a9?= References: <6fddc420-b582-cb2f-92ce-b3e067c420c4@suse.com> <20200428161412.GU28601@Air-de-Roger> From: Jan Beulich Message-ID: Date: Wed, 29 Apr 2020 09:37:11 +0200 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:68.0) Gecko/20100101 Thunderbird/68.7.0 MIME-Version: 1.0 In-Reply-To: <20200428161412.GU28601@Air-de-Roger> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit X-BeenThere: xen-devel@lists.xenproject.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Cc: "xen-devel@lists.xenproject.org" , Varad Gautam , Andrew Cooper , Wei Liu , Paul Durrant Errors-To: xen-devel-bounces@lists.xenproject.org Sender: "Xen-devel" On 28.04.2020 18:14, Roger Pau Monné wrote: > On Tue, Apr 28, 2020 at 02:21:48PM +0200, Jan Beulich wrote: >> XEN_DOMCTL_destroydomain creates a continuation if domain_kill -ERESTARTs. >> In that scenario, it is possible to receive multiple _pirq_guest_unbind >> calls for the same pirq from domain_kill, if the pirq has not yet been >> removed from the domain's pirq_tree, as: >> domain_kill() >> -> domain_relinquish_resources() >> -> pci_release_devices() >> -> pci_clean_dpci_irq() >> -> pirq_guest_unbind() >> -> __pirq_guest_unbind() >> >> Avoid recurring invocations of pirq_guest_unbind() by removing the pIRQ >> from the tree being iterated after the first call there. In case such a >> removed entry still has a softirq outstanding, record it and re-check >> upon re-invocation. >> >> Reported-by: Varad Gautam >> Signed-off-by: Jan Beulich >> Tested-by: Varad Gautam >> >> --- a/xen/arch/x86/irq.c >> +++ b/xen/arch/x86/irq.c >> @@ -1323,7 +1323,7 @@ void (pirq_cleanup_check)(struct pirq *p >> } >> >> if ( radix_tree_delete(&d->pirq_tree, pirq->pirq) != pirq ) >> - BUG(); >> + BUG_ON(!d->is_dying); > > I think to keep the previous behavior this should be: > > BUG_ON(!is_hvm_domain(d) || !d->is_dying); > > Since the pirqs will only be removed elsewhere if the domain is HVM? pirq_cleanup_check() is a generic hook, and hence I consider it more correct to not have it behave differently in this regard for different types of guests. IOW while it _may_ (didn't check) not be the case today that this can be called multiple times even for PV guests, I'd view this as legitimate behavior. Jan