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=DKIM_INVALID,DKIM_SIGNED, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS 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 7964FC433E0 for ; Mon, 6 Jul 2020 10:11:22 +0000 (UTC) Received: from mm01.cs.columbia.edu (mm01.cs.columbia.edu [128.59.11.253]) by mail.kernel.org (Postfix) with ESMTP id E53FC20739 for ; Mon, 6 Jul 2020 10:11:21 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="lKmXP9LG" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org E53FC20739 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kvmarm-bounces@lists.cs.columbia.edu Received: from localhost (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id 8A1DD4B408; Mon, 6 Jul 2020 06:11:21 -0400 (EDT) X-Virus-Scanned: at lists.cs.columbia.edu Authentication-Results: mm01.cs.columbia.edu (amavisd-new); dkim=softfail (fail, message has been altered) header.i=@kernel.org Received: from mm01.cs.columbia.edu ([127.0.0.1]) by localhost (mm01.cs.columbia.edu [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id fx9emWKu58Ve; Mon, 6 Jul 2020 06:11:20 -0400 (EDT) Received: from mm01.cs.columbia.edu (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id 7C6334B3E7; Mon, 6 Jul 2020 06:11:20 -0400 (EDT) Received: from localhost (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id 64A4D4B3D1 for ; Mon, 6 Jul 2020 06:11:19 -0400 (EDT) X-Virus-Scanned: at lists.cs.columbia.edu Received: from mm01.cs.columbia.edu ([127.0.0.1]) by localhost (mm01.cs.columbia.edu [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id ocgXivRbF9Q3 for ; Mon, 6 Jul 2020 06:11:18 -0400 (EDT) Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by mm01.cs.columbia.edu (Postfix) with ESMTPS id 4D0994B3C9 for ; Mon, 6 Jul 2020 06:11:18 -0400 (EDT) Received: from disco-boy.misterjones.org (disco-boy.misterjones.org [51.254.78.96]) (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 34C9420739; Mon, 6 Jul 2020 10:11:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1594030277; bh=mPPsT1QIJ2Rp9EBVG+gL+haA6Wlv2nggAMWKvcF4MEk=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=lKmXP9LG0URaJmbrToTyGAAN/X/eL5vXkwCjN1tihkuIA+MedOEizTLcqAxvOtV+/ V1yfW8sPlaBCCCrbzWyuK8wlZACeoLDO/UjTV7yqOBc5Lv31qLgzss0/wtNyrlzNeA Q/TSzT++Cw8HJAtcbQ1wBLjv+flOqNSWMO6rgC9A= Received: from disco-boy.misterjones.org ([51.254.78.96] helo=www.loen.fr) by disco-boy.misterjones.org with esmtpsa (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.92) (envelope-from ) id 1jsO5j-009Q3j-Fu; Mon, 06 Jul 2020 11:11:15 +0100 MIME-Version: 1.0 Date: Mon, 06 Jul 2020 11:11:15 +0100 From: Marc Zyngier To: Andrew Scull Subject: Re: [PATCH] arm64: kvm: Stop clobbering x0 for HVC_SOFT_RESTART In-Reply-To: <20200706095259.1338221-1-ascull@google.com> References: <20200706095259.1338221-1-ascull@google.com> User-Agent: Roundcube Webmail/1.4.5 Message-ID: X-Sender: maz@kernel.org X-SA-Exim-Connect-IP: 51.254.78.96 X-SA-Exim-Rcpt-To: ascull@google.com, kvmarm@lists.cs.columbia.edu, james.morse@arm.com, suzuki.poulose@arm.com, julien.thierry.kdev@gmail.com, kernel-team@android.com X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on disco-boy.misterjones.org); SAEximRunCond expanded to false Cc: kernel-team@android.com, kvmarm@lists.cs.columbia.edu X-BeenThere: kvmarm@lists.cs.columbia.edu X-Mailman-Version: 2.1.14 Precedence: list List-Id: Where KVM/ARM decisions are made List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Errors-To: kvmarm-bounces@lists.cs.columbia.edu Sender: kvmarm-bounces@lists.cs.columbia.edu On 2020-07-06 10:52, Andrew Scull wrote: > HVC_SOFT_RESTART is given values for x0-2 that it should installed > before exiting to the new address so should not set x0 to stub HVC > success or failure code. > > Signed-off-by: Andrew Scull > --- > arch/arm64/kvm/hyp-init.S | 11 +++++++---- > 1 file changed, 7 insertions(+), 4 deletions(-) > > diff --git a/arch/arm64/kvm/hyp-init.S b/arch/arm64/kvm/hyp-init.S > index 6e6ed5581eed..e76c0e89d48e 100644 > --- a/arch/arm64/kvm/hyp-init.S > +++ b/arch/arm64/kvm/hyp-init.S > @@ -136,11 +136,15 @@ SYM_CODE_START(__kvm_handle_stub_hvc) > > 1: cmp x0, #HVC_RESET_VECTORS > b.ne 1f > -reset: > + > /* > - * Reset kvm back to the hyp stub. Do not clobber x0-x4 in > - * case we coming via HVC_SOFT_RESTART. > + * Set the HVC_RESET_VECTORS return code before entering the common > + * path so that we do not clobber x0-x2 in case we are coming via > + * HVC_SOFT_RESTART. > */ > + mov x0, xzr > +reset: > + /* Reset kvm back to the hyp stub. */ > mrs x5, sctlr_el2 > mov_q x6, SCTLR_ELx_FLAGS > bic x5, x5, x6 // Clear SCTL_M and etc > @@ -151,7 +155,6 @@ reset: > /* Install stub vectors */ > adr_l x5, __hyp_stub_vectors > msr vbar_el2, x5 > - mov x0, xzr > eret > > 1: /* Bad stub call */ Huh, nice catch. I wonder what the fuss is about kexec, really, given that it is *that* broken. This deserves: Fixes: af42f20480bf1 ("arm64: hyp-stub: Zero x0 on successful stub handling") Cc: stable@vger.kernel.org Thanks, M. -- Jazz is not dead. It just smells funny... _______________________________________________ kvmarm mailing list kvmarm@lists.cs.columbia.edu https://lists.cs.columbia.edu/mailman/listinfo/kvmarm