From patchwork Tue Nov 3 16:22:28 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Juergen Gross X-Patchwork-Id: 317256 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=-12.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH, MAILING_LIST_MULTI, SIGNED_OFF_BY, SPF_HELO_NONE, SPF_PASS, URIBL_BLOCKED, USER_AGENT_GIT 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 C427EC2D0A3 for ; Tue, 3 Nov 2020 16:22:41 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 69E3E223FD for ; Tue, 3 Nov 2020 16:22:41 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=suse.com header.i=@suse.com header.b="RB1AXnct" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727971AbgKCQWk (ORCPT ); Tue, 3 Nov 2020 11:22:40 -0500 Received: from mx2.suse.de ([195.135.220.15]:58708 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727742AbgKCQWk (ORCPT ); Tue, 3 Nov 2020 11:22:40 -0500 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=1604420559; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=gh5d4E3mIBlrpqbMhPhBBSyGmnz9IOcgQriut1Y0Nvs=; b=RB1AXnct0tzRSrlz4YU1ER4bUFfRYd3M1j8DG6hElUXwVkLFR9b3YlzutlI+ib3L1VxUgy p3gXrqxTm0Hp/2hLDN87g31hdKzu5TqGkaUJWY3f4AvAEjgTjNxd+LdBlKmN6js3nW09Fb KbOW0Wvp06PUMMVprK5Q56jQ1z0ncV8= Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 95CA3AD43 for ; Tue, 3 Nov 2020 16:22:39 +0000 (UTC) From: Juergen Gross To: stable@vger.kernel.org Subject: [PATCH 03/13] xen/events: add a proper barrier to 2-level uevent unmasking Date: Tue, 3 Nov 2020 17:22:28 +0100 Message-Id: <20201103162238.30264-4-jgross@suse.com> X-Mailer: git-send-email 2.26.2 In-Reply-To: <20201103162238.30264-1-jgross@suse.com> References: <20201103162238.30264-1-jgross@suse.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org A follow-up patch will require certain write to happen before an event channel is unmasked. While the memory barrier is not strictly necessary for all the callers, the main one will need it. In order to avoid an extra memory barrier when using fifo event channels, mandate evtchn_unmask() to provide write ordering. The 2-level event handling unmask operation is missing an appropriate barrier, so add it. Fifo event channels are fine in this regard due to using sync_cmpxchg(). This is part of XSA-332. This is upstream commit 4d3fe31bd993ef504350989786858aefdb877daa Cc: stable@vger.kernel.org Suggested-by: Julien Grall Signed-off-by: Juergen Gross Reviewed-by: Julien Grall Reviewed-by: Wei Liu --- drivers/xen/events/events_2l.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/drivers/xen/events/events_2l.c b/drivers/xen/events/events_2l.c index 7dd46312c180..04d1b025b29d 100644 --- a/drivers/xen/events/events_2l.c +++ b/drivers/xen/events/events_2l.c @@ -90,6 +90,8 @@ static void evtchn_2l_unmask(unsigned port) BUG_ON(!irqs_disabled()); + smp_wmb(); /* All writes before unmask must be visible. */ + if (unlikely((cpu != cpu_from_evtchn(port)))) do_hypercall = 1; else {