Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 120B5C433FE for ; Mon, 15 Nov 2021 17:22:48 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id F1311632BD for ; Mon, 15 Nov 2021 17:22:47 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237481AbhKORZk (ORCPT ); Mon, 15 Nov 2021 12:25:40 -0500 Received: from mail.kernel.org ([198.145.29.99]:46816 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236880AbhKOROC (ORCPT ); Mon, 15 Nov 2021 12:14:02 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id 4170A63236; Mon, 15 Nov 2021 17:10:40 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1636996240; bh=VCo8KtT/4m2feGM5iJzv4Hn3WiPiRGxGUVYg9xke834=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=qvI7RRhncBUVxZiLU4gKBgxnU4ffx+CzmAwH/toGEfvrH3ElVGQIjfWDYPQNzvqy9 Py/G9PFtinN8ixo0Epxj5FAgNcjGj1kBwqpEqb/H7VNdLkkd3b0zZauCqIjTwP6clG lWzLoWiXnJ4DUX51tgSW3y66K0C8RSNteI+NWbFM= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Sean Christopherson , Paolo Bonzini Subject: [PATCH 5.4 035/355] x86/irq: Ensure PI wakeup handler is unregistered before module unload Date: Mon, 15 Nov 2021 17:59:19 +0100 Message-Id: <20211115165314.681867989@linuxfoundation.org> X-Mailer: git-send-email 2.33.1 In-Reply-To: <20211115165313.549179499@linuxfoundation.org> References: <20211115165313.549179499@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Sean Christopherson commit 6ff53f6a438f72998f56e82e76694a1df9d1ea2c upstream. Add a synchronize_rcu() after clearing the posted interrupt wakeup handler to ensure all readers, i.e. in-flight IRQ handlers, see the new handler before returning to the caller. If the caller is an exiting module and is unregistering its handler, failure to wait could result in the IRQ handler jumping into an unloaded module. The registration path doesn't require synchronization, as it's the caller's responsibility to not generate interrupts it cares about until after its handler is registered. Fixes: f6b3c72c2366 ("x86/irq: Define a global vector for VT-d Posted-Interrupts") Cc: stable@vger.kernel.org Signed-off-by: Sean Christopherson Message-Id: <20211009001107.3936588-2-seanjc@google.com> Signed-off-by: Paolo Bonzini Signed-off-by: Greg Kroah-Hartman --- arch/x86/kernel/irq.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) --- a/arch/x86/kernel/irq.c +++ b/arch/x86/kernel/irq.c @@ -295,8 +295,10 @@ void kvm_set_posted_intr_wakeup_handler( { if (handler) kvm_posted_intr_wakeup_handler = handler; - else + else { kvm_posted_intr_wakeup_handler = dummy_handler; + synchronize_rcu(); + } } EXPORT_SYMBOL_GPL(kvm_set_posted_intr_wakeup_handler);