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=-6.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,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 E2C35C2BA83 for ; Thu, 13 Feb 2020 15:33:59 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id BB77C20675 for ; Thu, 13 Feb 2020 15:33:59 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1581608039; bh=q8XtGX2CbdDm3oYTtQ6OZ88EQxl5iLM35Nkg4DPXLVY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=AmiCHpxExBgcvG1rg6ex6yNJoLJplJAq7zDJCUPUwvCUdngLJYqUVDr8yrQ4lrL3l Gzk7vVJXn68nn61mL6ApKEiNpCJGxNHkM5vykisGLYvarsu+42HyJlMrjkPZdczHf9 r21TG34ydV71A7buwWJhQ2zGq0xT5KmVGYH220Wo= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388243AbgBMPd6 (ORCPT ); Thu, 13 Feb 2020 10:33:58 -0500 Received: from mail.kernel.org ([198.145.29.99]:59638 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729690AbgBMP3P (ORCPT ); Thu, 13 Feb 2020 10:29:15 -0500 Received: from localhost (unknown [104.132.1.104]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id EC44424688; Thu, 13 Feb 2020 15:29:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1581607755; bh=q8XtGX2CbdDm3oYTtQ6OZ88EQxl5iLM35Nkg4DPXLVY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=f+zg2uNUgRRkzmipCzVv+iVIh2Nd50nYkrmEFAngVvjelZm+uOx4Te8ZsTDpKBJZ3 Lqjps/b9NjKM1TS1NAFWoIwZgETsGr+WtlXr4M8/XSvTrg1Wq5vB51WWwfBDy+v545 rGuH7Q7FUGGBMTBmtTCZGM0eXrwVbO5svw6AvPSg= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Alexandru Elisei , Marc Zyngier Subject: [PATCH 5.5 090/120] KVM: arm64: Treat emulated TVAL TimerValue as a signed 32-bit integer Date: Thu, 13 Feb 2020 07:21:26 -0800 Message-Id: <20200213151931.495371546@linuxfoundation.org> X-Mailer: git-send-email 2.25.0 In-Reply-To: <20200213151901.039700531@linuxfoundation.org> References: <20200213151901.039700531@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Alexandru Elisei commit 4a267aa707953a9a73d1f5dc7f894dd9024a92be upstream. According to the ARM ARM, registers CNT{P,V}_TVAL_EL0 have bits [63:32] RES0 [1]. When reading the register, the value is truncated to the least significant 32 bits [2], and on writes, TimerValue is treated as a signed 32-bit integer [1, 2]. When the guest behaves correctly and writes 32-bit values, treating TVAL as an unsigned 64 bit register works as expected. However, things start to break down when the guest writes larger values, because (u64)0x1_ffff_ffff = 8589934591. but (s32)0x1_ffff_ffff = -1, and the former will cause the timer interrupt to be asserted in the future, but the latter will cause it to be asserted now. Let's treat TVAL as a signed 32-bit register on writes, to match the behaviour described in the architecture, and the behaviour experimentally exhibited by the virtual timer on a non-vhe host. [1] Arm DDI 0487E.a, section D13.8.18 [2] Arm DDI 0487E.a, section D11.2.4 Signed-off-by: Alexandru Elisei [maz: replaced the read-side mask with lower_32_bits] Signed-off-by: Marc Zyngier Fixes: 8fa761624871 ("KVM: arm/arm64: arch_timer: Fix CNTP_TVAL calculation") Link: https://lore.kernel.org/r/20200127103652.2326-1-alexandru.elisei@arm.com Signed-off-by: Greg Kroah-Hartman --- virt/kvm/arm/arch_timer.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) --- a/virt/kvm/arm/arch_timer.c +++ b/virt/kvm/arm/arch_timer.c @@ -805,6 +805,7 @@ static u64 kvm_arm_timer_read(struct kvm switch (treg) { case TIMER_REG_TVAL: val = timer->cnt_cval - kvm_phys_timer_read() + timer->cntvoff; + val &= lower_32_bits(val); break; case TIMER_REG_CTL: @@ -850,7 +851,7 @@ static void kvm_arm_timer_write(struct k { switch (treg) { case TIMER_REG_TVAL: - timer->cnt_cval = kvm_phys_timer_read() - timer->cntvoff + val; + timer->cnt_cval = kvm_phys_timer_read() - timer->cntvoff + (s32)val; break; case TIMER_REG_CTL: