From patchwork Tue Oct 20 14:10:54 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jan Beulich X-Patchwork-Id: 11847085 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id C77F814B4 for ; Tue, 20 Oct 2020 14:12:23 +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 89BCE2098B for ; Tue, 20 Oct 2020 14:12:23 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=suse.com header.i=@suse.com header.b="XQDD2rgF" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 89BCE2098B Authentication-Results: mail.kernel.org; dmarc=fail (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 list by lists.xenproject.org with outflank-mailman.9667.25417 (Exim 4.92) (envelope-from ) id 1kUsLq-00020f-LL; Tue, 20 Oct 2020 14:10:58 +0000 X-Outflank-Mailman: Message body and most headers restored to incoming version Received: by outflank-mailman (output) from mailman id 9667.25417; Tue, 20 Oct 2020 14:10:58 +0000 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" Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1kUsLq-00020Y-HN; Tue, 20 Oct 2020 14:10:58 +0000 Received: by outflank-mailman (input) for mailman id 9667; Tue, 20 Oct 2020 14:10:57 +0000 Received: from us1-rack-iad1.inumbo.com ([172.99.69.81]) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1kUsLp-00020L-7E for xen-devel@lists.xenproject.org; Tue, 20 Oct 2020 14:10:57 +0000 Received: from mx2.suse.de (unknown [195.135.220.15]) by us1-rack-iad1.inumbo.com (Halon) with ESMTPS id d8ab37ee-23aa-4929-9bc3-89900844491d; Tue, 20 Oct 2020 14:10:55 +0000 (UTC) Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 2EBC7AC6A; Tue, 20 Oct 2020 14:10:55 +0000 (UTC) Received: from us1-rack-iad1.inumbo.com ([172.99.69.81]) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1kUsLp-00020L-7E for xen-devel@lists.xenproject.org; Tue, 20 Oct 2020 14:10:57 +0000 X-Inumbo-ID: d8ab37ee-23aa-4929-9bc3-89900844491d Received: from mx2.suse.de (unknown [195.135.220.15]) by us1-rack-iad1.inumbo.com (Halon) with ESMTPS id d8ab37ee-23aa-4929-9bc3-89900844491d; Tue, 20 Oct 2020 14:10:55 +0000 (UTC) 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=1603203055; 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=htCKeLk050dUSTPkbNMbWkMtxwQVWeeYQPtwH2yDG7s=; b=XQDD2rgF+nL8IETAnhFBJqQXLoRjN5PBxYjw/Z+puWmois3/RhdAXqzeqFefDZDN69dJHc sEPPhn3rLphXG9K1Nv28fWAh2QnJQ4+NHu3T8fSJGDYXQuQmKTPQYsxlWRPPQcfLvsFgze QZqX5ENS4U9nIt4RIxpb6Gm/str1lac= Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 2EBC7AC6A; Tue, 20 Oct 2020 14:10:55 +0000 (UTC) Subject: [PATCH v2 6/8] evtchn: convert vIRQ lock to an r/w one From: Jan Beulich To: "xen-devel@lists.xenproject.org" Cc: Andrew Cooper , George Dunlap , Ian Jackson , Julien Grall , Wei Liu , Stefano Stabellini References: <19babf20-3649-5c63-44a9-7edfa81835aa@suse.com> Message-ID: <53a2fc39-1bf1-38ce-bbdf-b512c5279b4f@suse.com> Date: Tue, 20 Oct 2020 16:10:54 +0200 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:68.0) Gecko/20100101 Thunderbird/68.12.1 MIME-Version: 1.0 In-Reply-To: <19babf20-3649-5c63-44a9-7edfa81835aa@suse.com> Content-Language: en-US There's no need to serialize all sending of vIRQ-s; all that's needed is serialization against the closing of the respective event channels (so far by means of a barrier). To facilitate the conversion, switch to an ordinary write locked region in evtchn_close(). Signed-off-by: Jan Beulich --- v2: Don't introduce/use rw_barrier() here. Add comment to evtchn_bind_virq(). Re-base. --- a/xen/common/domain.c +++ b/xen/common/domain.c @@ -160,7 +160,7 @@ struct vcpu *vcpu_create(struct domain * v->vcpu_id = vcpu_id; v->dirty_cpu = VCPU_CPU_CLEAN; - spin_lock_init(&v->virq_lock); + rwlock_init(&v->virq_lock); tasklet_init(&v->continue_hypercall_tasklet, NULL, NULL); --- a/xen/common/event_channel.c +++ b/xen/common/event_channel.c @@ -449,6 +449,13 @@ int evtchn_bind_virq(evtchn_bind_virq_t spin_unlock_irqrestore(&chn->lock, flags); + /* + * If by any, the update of virq_to_evtchn[] would need guarding by + * virq_lock, but since this is the last action here, there's no strict + * need to acquire the lock. Hnece holding event_lock isn't helpful + * anymore at this point, but utilize that its unlocking acts as the + * otherwise necessary smp_wmb() here. + */ v->virq_to_evtchn[virq] = bind->port = port; out: @@ -638,10 +645,10 @@ int evtchn_close(struct domain *d1, int case ECS_VIRQ: for_each_vcpu ( d1, v ) { - if ( v->virq_to_evtchn[chn1->u.virq] != port1 ) - continue; - v->virq_to_evtchn[chn1->u.virq] = 0; - spin_barrier(&v->virq_lock); + write_lock_irqsave(&v->virq_lock, flags); + if ( v->virq_to_evtchn[chn1->u.virq] == port1 ) + v->virq_to_evtchn[chn1->u.virq] = 0; + write_unlock_irqrestore(&v->virq_lock, flags); } break; @@ -797,7 +804,7 @@ void send_guest_vcpu_virq(struct vcpu *v ASSERT(!virq_is_global(virq)); - spin_lock_irqsave(&v->virq_lock, flags); + read_lock_irqsave(&v->virq_lock, flags); port = v->virq_to_evtchn[virq]; if ( unlikely(port == 0) ) @@ -807,7 +814,7 @@ void send_guest_vcpu_virq(struct vcpu *v evtchn_port_set_pending(d, v->vcpu_id, evtchn_from_port(d, port)); out: - spin_unlock_irqrestore(&v->virq_lock, flags); + read_unlock_irqrestore(&v->virq_lock, flags); } void send_guest_global_virq(struct domain *d, uint32_t virq) @@ -826,7 +833,7 @@ void send_guest_global_virq(struct domai if ( unlikely(v == NULL) ) return; - spin_lock_irqsave(&v->virq_lock, flags); + read_lock_irqsave(&v->virq_lock, flags); port = v->virq_to_evtchn[virq]; if ( unlikely(port == 0) ) @@ -836,7 +843,7 @@ void send_guest_global_virq(struct domai evtchn_port_set_pending(d, chn->notify_vcpu_id, chn); out: - spin_unlock_irqrestore(&v->virq_lock, flags); + read_unlock_irqrestore(&v->virq_lock, flags); } void send_guest_pirq(struct domain *d, const struct pirq *pirq) --- a/xen/include/xen/sched.h +++ b/xen/include/xen/sched.h @@ -235,7 +235,7 @@ struct vcpu /* IRQ-safe virq_lock protects against delivering VIRQ to stale evtchn. */ evtchn_port_t virq_to_evtchn[NR_VIRQS]; - spinlock_t virq_lock; + rwlock_t virq_lock; /* Tasklet for continue_hypercall_on_cpu(). */ struct tasklet continue_hypercall_tasklet;