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=-8.5 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_1 autolearn=unavailable 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 ED89AC433E2 for ; Wed, 15 Jul 2020 11:56:59 +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 C515D20658 for ; Wed, 15 Jul 2020 11:56:59 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org C515D20658 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 1jvg1p-0000cm-FV; Wed, 15 Jul 2020 11:56:49 +0000 Received: from us1-rack-iad1.inumbo.com ([172.99.69.81]) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1jvg1o-0000ce-97 for xen-devel@lists.xenproject.org; Wed, 15 Jul 2020 11:56:48 +0000 X-Inumbo-ID: 428134fe-c692-11ea-bb8b-bc764e2007e4 Received: from mx2.suse.de (unknown [195.135.220.15]) by us1-rack-iad1.inumbo.com (Halon) with ESMTPS id 428134fe-c692-11ea-bb8b-bc764e2007e4; Wed, 15 Jul 2020 11:56:47 +0000 (UTC) X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 0CEE4AC7D; Wed, 15 Jul 2020 11:56:50 +0000 (UTC) Subject: [PATCH v3 1/2] x86: restore pv_rtc_handler() invocation From: Jan Beulich To: "xen-devel@lists.xenproject.org" References: <5426dd6f-50cd-dc23-5c6b-0ab631d98d38@suse.com> Message-ID: <7dd4b668-06ca-807a-9cc1-77430b2376a8@suse.com> Date: Wed, 15 Jul 2020 13:56:47 +0200 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: <5426dd6f-50cd-dc23-5c6b-0ab631d98d38@suse.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit 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: Andrew Cooper , =?UTF-8?Q?Roger_Pau_Monn=c3=a9?= , Wei Liu , Paul Durrant Errors-To: xen-devel-bounces@lists.xenproject.org Sender: "Xen-devel" This was lost when making the logic accessible to PVH Dom0. While doing so make the access to the global function pointer safe against races (as noticed by Roger): The only current user wants to be invoked just once (but can tolerate to be invoked multiple times), zapping the pointer at that point. Fixes: 835d8d69d96a ("x86/rtc: provide mediated access to RTC for PVH dom0") Signed-off-by: Jan Beulich --- v3: Latch pointer under lock. v2: New. --- a/xen/arch/x86/time.c +++ b/xen/arch/x86/time.c @@ -1148,6 +1148,8 @@ void rtc_guest_write(unsigned int port, switch ( port ) { + typeof(pv_rtc_handler) hook; + case RTC_PORT(0): /* * All PV domains (and PVH dom0) are allowed to write to the latched @@ -1160,6 +1162,14 @@ void rtc_guest_write(unsigned int port, case RTC_PORT(1): if ( !ioports_access_permitted(currd, RTC_PORT(0), RTC_PORT(1)) ) break; + + spin_lock_irqsave(&rtc_lock, flags); + hook = pv_rtc_handler; + spin_unlock_irqrestore(&rtc_lock, flags); + + if ( hook ) + hook(currd->arch.cmos_idx & 0x7f, data); + spin_lock_irqsave(&rtc_lock, flags); outb(currd->arch.cmos_idx & 0x7f, RTC_PORT(0)); outb(data, RTC_PORT(1));