From nobody Mon Feb 9 11:29:55 2026 Delivered-To: importer@patchew.org Received-SPF: pass (zohomail.com: domain of lists.xenproject.org designates 192.237.175.120 as permitted sender) client-ip=192.237.175.120; envelope-from=xen-devel-bounces@lists.xenproject.org; helo=lists.xenproject.org; Authentication-Results: mx.zohomail.com; dkim=pass; spf=pass (zohomail.com: domain of lists.xenproject.org designates 192.237.175.120 as permitted sender) smtp.mailfrom=xen-devel-bounces@lists.xenproject.org; dmarc=pass(p=quarantine dis=none) header.from=suse.com ARC-Seal: i=1; a=rsa-sha256; t=1611735340; cv=none; d=zohomail.com; s=zohoarc; b=l3oQGYKWJ5bHE5ebgAakHOElD4/NoRn+uYnUDcQpxW3puZ4UXHY/vvUUzZ7YHbFETNvNlyjzhqFGeERRL5WApifZxgLLrXJaD03CqdKFGgn9J2aeLyQ2lGgrtZfNfLlQEdJOHhZJHPBAw/Vkc87THlj8mvkceDFZWg/RnBhoCg4= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=zohomail.com; s=zohoarc; t=1611735340; h=Content-Type:Content-Transfer-Encoding:Cc:Date:From:In-Reply-To:List-Subscribe:List-Post:List-Id:List-Help:List-Unsubscribe:MIME-Version:Message-ID:References:Sender:Subject:To; bh=kJW/wMgZhZCk29BDYV5bG2rGCyC3dQXKAGN0v9QFQbc=; b=hBtq4EYGxmLyn3GP4lopSseqtuInBQgg3nYWse26Vfu0e3brFQD82TjQ5bys+LVjr6WINk3c+avkEKjbWmy4XvsgqXURA9yij4/iG0F//kQGA3lhU04Gm2i8X1g6om0OZl1hMs9gebI9LyUyEknMZOug3IJn+vp9J8sEcmbQW6M= ARC-Authentication-Results: i=1; mx.zohomail.com; dkim=pass; spf=pass (zohomail.com: domain of lists.xenproject.org designates 192.237.175.120 as permitted sender) smtp.mailfrom=xen-devel-bounces@lists.xenproject.org; dmarc=pass header.from= (p=quarantine dis=none) header.from= Return-Path: Received: from lists.xenproject.org (lists.xenproject.org [192.237.175.120]) by mx.zohomail.com with SMTPS id 1611735340942847.6528012345192; Wed, 27 Jan 2021 00:15:40 -0800 (PST) Received: from list by lists.xenproject.org with outflank-mailman.75791.136548 (Exim 4.92) (envelope-from ) id 1l4fz0-0005Xx-3M; Wed, 27 Jan 2021 08:15:22 +0000 Received: by outflank-mailman (output) from mailman id 75791.136548; Wed, 27 Jan 2021 08:15:22 +0000 Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1l4fyz-0005Xq-UK; Wed, 27 Jan 2021 08:15:21 +0000 Received: by outflank-mailman (input) for mailman id 75791; Wed, 27 Jan 2021 08:15:21 +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 1l4fyz-0005Xl-4N for xen-devel@lists.xenproject.org; Wed, 27 Jan 2021 08:15:21 +0000 Received: from mx2.suse.de (unknown [195.135.220.15]) by us1-amaz-eas2.inumbo.com (Halon) with ESMTPS id f85644b1-0360-4f28-9457-ad7b2787e0ed; Wed, 27 Jan 2021 08:15:15 +0000 (UTC) Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 43194AD7F; Wed, 27 Jan 2021 08:15:14 +0000 (UTC) X-Outflank-Mailman: Message body and most headers restored to incoming version X-BeenThere: xen-devel@lists.xenproject.org List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Errors-To: xen-devel-bounces@lists.xenproject.org Precedence: list Sender: "Xen-devel" X-Inumbo-ID: f85644b1-0360-4f28-9457-ad7b2787e0ed X-Virus-Scanned: by amavisd-new at test-mx.suse.de DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1611735314; h=from:from:reply-to: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=kJW/wMgZhZCk29BDYV5bG2rGCyC3dQXKAGN0v9QFQbc=; b=VFe0AdolORphdj2WdblAICjqD6xElm2R1NQ3LEbQViI+r2yTQc4XnoOqviH/NWHNnieA+Q oXbnWohNP3DiPk56WFzLNwhUnmoaYP7oFM7MRWxzVCMkADVwC05+1CzVcwvO0a337xo943 7HyOUTGPTjCXaMisdwWeTwFk6olNLRk= Subject: [PATCH v5 1/6] evtchn: use per-channel lock where possible From: Jan Beulich To: "xen-devel@lists.xenproject.org" Cc: Andrew Cooper , George Dunlap , Ian Jackson , Julien Grall , Wei Liu , Stefano Stabellini References: <306e62e8-9070-2db9-c959-858465c50c1d@suse.com> Message-ID: <081b2253-e445-4242-3f0c-0f2912412d43@suse.com> Date: Wed, 27 Jan 2021 09:15:14 +0100 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.6.1 MIME-Version: 1.0 In-Reply-To: <306e62e8-9070-2db9-c959-858465c50c1d@suse.com> Content-Language: en-US Content-Transfer-Encoding: quoted-printable X-ZohoMail-DKIM: pass (identity @suse.com) Content-Type: text/plain; charset="utf-8" Neither evtchn_status() nor domain_dump_evtchn_info() nor flask_get_peer_sid() need to hold the per-domain lock - they all only read a single channel's state (at a time, in the dump case). Signed-off-by: Jan Beulich --- v4: New. --- a/xen/common/event_channel.c +++ b/xen/common/event_channel.c @@ -974,15 +974,16 @@ int evtchn_status(evtchn_status_t *statu if ( d =3D=3D NULL ) return -ESRCH; =20 - spin_lock(&d->event_lock); - if ( !port_is_valid(d, port) ) { - rc =3D -EINVAL; - goto out; + rcu_unlock_domain(d); + return -EINVAL; } =20 chn =3D evtchn_from_port(d, port); + + evtchn_read_lock(chn); + if ( consumer_is_xen(chn) ) { rc =3D -EACCES; @@ -1027,7 +1028,7 @@ int evtchn_status(evtchn_status_t *statu status->vcpu =3D chn->notify_vcpu_id; =20 out: - spin_unlock(&d->event_lock); + evtchn_read_unlock(chn); rcu_unlock_domain(d); =20 return rc; @@ -1582,22 +1583,32 @@ void evtchn_move_pirqs(struct vcpu *v) static void domain_dump_evtchn_info(struct domain *d) { unsigned int port; - int irq; =20 printk("Event channel information for domain %d:\n" "Polling vCPUs: {%*pbl}\n" " port [p/m/s]\n", d->domain_id, d->max_vcpus, d->poll_mask); =20 - spin_lock(&d->event_lock); - for ( port =3D 1; port_is_valid(d, port); ++port ) { - const struct evtchn *chn; + struct evtchn *chn; char *ssid; =20 + if ( !(port & 0x3f) ) + process_pending_softirqs(); + chn =3D evtchn_from_port(d, port); + + if ( !evtchn_read_trylock(chn) ) + { + printk(" %4u in flux\n", port); + continue; + } + if ( chn->state =3D=3D ECS_FREE ) + { + evtchn_read_unlock(chn); continue; + } =20 printk(" %4u [%d/%d/", port, @@ -1607,26 +1618,49 @@ static void domain_dump_evtchn_info(stru printk("]: s=3D%d n=3D%d x=3D%d", chn->state, chn->notify_vcpu_id, chn->xen_consumer); =20 + ssid =3D xsm_show_security_evtchn(d, chn); + switch ( chn->state ) { case ECS_UNBOUND: printk(" d=3D%d", chn->u.unbound.remote_domid); break; + case ECS_INTERDOMAIN: printk(" d=3D%d p=3D%d", chn->u.interdomain.remote_dom->domain_id, chn->u.interdomain.remote_port); break; - case ECS_PIRQ: - irq =3D domain_pirq_to_irq(d, chn->u.pirq.irq); - printk(" p=3D%d i=3D%d", chn->u.pirq.irq, irq); + + case ECS_PIRQ: { + unsigned int pirq =3D chn->u.pirq.irq; + + /* + * The per-channel locks nest inside the per-domain one, so we + * can't acquire the latter without first letting go of the fo= rmer. + */ + evtchn_read_unlock(chn); + chn =3D NULL; + if ( spin_trylock(&d->event_lock) ) + { + int irq =3D domain_pirq_to_irq(d, pirq); + + spin_unlock(&d->event_lock); + printk(" p=3D%u i=3D%d", pirq, irq); + } + else + printk(" p=3D%u i=3D?", pirq); break; + } + case ECS_VIRQ: printk(" v=3D%d", chn->u.virq); break; } =20 - ssid =3D xsm_show_security_evtchn(d, chn); + if ( chn ) + evtchn_read_unlock(chn); + if (ssid) { printk(" Z=3D%s\n", ssid); xfree(ssid); @@ -1634,8 +1668,6 @@ static void domain_dump_evtchn_info(stru printk("\n"); } } - - spin_unlock(&d->event_lock); } =20 static void dump_evtchn_info(unsigned char key) --- a/xen/xsm/flask/flask_op.c +++ b/xen/xsm/flask/flask_op.c @@ -555,12 +555,13 @@ static int flask_get_peer_sid(struct xen struct evtchn *chn; struct domain_security_struct *dsec; =20 - spin_lock(&d->event_lock); - if ( !port_is_valid(d, arg->evtchn) ) - goto out; + return -EINVAL; =20 chn =3D evtchn_from_port(d, arg->evtchn); + + evtchn_read_lock(chn); + if ( chn->state !=3D ECS_INTERDOMAIN ) goto out; =20 @@ -573,7 +574,7 @@ static int flask_get_peer_sid(struct xen rv =3D 0; =20 out: - spin_unlock(&d->event_lock); + evtchn_read_unlock(chn); return rv; } =20