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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2D787C433FE for ; Mon, 6 Dec 2021 15:25:29 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1377425AbhLFP2w (ORCPT ); Mon, 6 Dec 2021 10:28:52 -0500 Received: from dfw.source.kernel.org ([139.178.84.217]:41162 "EHLO dfw.source.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1347052AbhLFPYw (ORCPT ); Mon, 6 Dec 2021 10:24:52 -0500 Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id EF55061328; Mon, 6 Dec 2021 15:21:23 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id D5F88C341C5; Mon, 6 Dec 2021 15:21:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1638804083; bh=hQyTUfjEScAoD/ZE+L9HMWzpB6mgkVPAkpeRka90jZo=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=i3Af0OcMJrYMYPF/sDvnQDfvq5rNwgQEPwIP0w5Raoew9/4XTqDPPiYFmwWdVFjbs DC/ZD0ijvi6BTe/YNjJT34VdHekzul/pyG8mFkDRUbS012gcT78Tjth07fmK6COq/I bv/gkwWXd2ypFlffTit20b7aI4Hg4FeeU7KxZrTY= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Vitaly Kuznetsov , Sean Christopherson , Wei Liu , Sasha Levin Subject: [PATCH 5.15 020/207] x86/hyperv: Move required MSRs check to initial platform probing Date: Mon, 6 Dec 2021 15:54:34 +0100 Message-Id: <20211206145610.900057280@linuxfoundation.org> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20211206145610.172203682@linuxfoundation.org> References: <20211206145610.172203682@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: stable@vger.kernel.org From: Sean Christopherson [ Upstream commit f3e613e72f66226b3bea1046c1b864f67a3000a4 ] Explicitly check for MSR_HYPERCALL and MSR_VP_INDEX support when probing for running as a Hyper-V guest instead of waiting until hyperv_init() to detect the bogus configuration. Add messages to give the admin a heads up that they are likely running on a broken virtual machine setup. At best, silently disabling Hyper-V is confusing and difficult to debug, e.g. the kernel _says_ it's using all these fancy Hyper-V features, but always falls back to the native versions. At worst, the half baked setup will crash/hang the kernel. Reviewed-by: Vitaly Kuznetsov Signed-off-by: Sean Christopherson Link: https://lore.kernel.org/r/20211104182239.1302956-3-seanjc@google.com Signed-off-by: Wei Liu Signed-off-by: Sasha Levin --- arch/x86/hyperv/hv_init.c | 9 +-------- arch/x86/kernel/cpu/mshyperv.c | 20 +++++++++++++++----- 2 files changed, 16 insertions(+), 13 deletions(-) diff --git a/arch/x86/hyperv/hv_init.c b/arch/x86/hyperv/hv_init.c index d20eef3d452a5..b6d48ca5b0f17 100644 --- a/arch/x86/hyperv/hv_init.c +++ b/arch/x86/hyperv/hv_init.c @@ -348,20 +348,13 @@ static void __init hv_get_partition_id(void) */ void __init hyperv_init(void) { - u64 guest_id, required_msrs; + u64 guest_id; union hv_x64_msr_hypercall_contents hypercall_msr; int cpuhp; if (x86_hyper_type != X86_HYPER_MS_HYPERV) return; - /* Absolutely required MSRs */ - required_msrs = HV_MSR_HYPERCALL_AVAILABLE | - HV_MSR_VP_INDEX_AVAILABLE; - - if ((ms_hyperv.features & required_msrs) != required_msrs) - return; - if (hv_common_init()) return; diff --git a/arch/x86/kernel/cpu/mshyperv.c b/arch/x86/kernel/cpu/mshyperv.c index e095c28d27ae8..ef6316fef99ff 100644 --- a/arch/x86/kernel/cpu/mshyperv.c +++ b/arch/x86/kernel/cpu/mshyperv.c @@ -163,12 +163,22 @@ static uint32_t __init ms_hyperv_platform(void) cpuid(HYPERV_CPUID_VENDOR_AND_MAX_FUNCTIONS, &eax, &hyp_signature[0], &hyp_signature[1], &hyp_signature[2]); - if (eax >= HYPERV_CPUID_MIN && - eax <= HYPERV_CPUID_MAX && - !memcmp("Microsoft Hv", hyp_signature, 12)) - return HYPERV_CPUID_VENDOR_AND_MAX_FUNCTIONS; + if (eax < HYPERV_CPUID_MIN || eax > HYPERV_CPUID_MAX || + memcmp("Microsoft Hv", hyp_signature, 12)) + return 0; - return 0; + /* HYPERCALL and VP_INDEX MSRs are mandatory for all features. */ + eax = cpuid_eax(HYPERV_CPUID_FEATURES); + if (!(eax & HV_MSR_HYPERCALL_AVAILABLE)) { + pr_warn("x86/hyperv: HYPERCALL MSR not available.\n"); + return 0; + } + if (!(eax & HV_MSR_VP_INDEX_AVAILABLE)) { + pr_warn("x86/hyperv: VP_INDEX MSR not available.\n"); + return 0; + } + + return HYPERV_CPUID_VENDOR_AND_MAX_FUNCTIONS; } static unsigned char hv_get_nmi_reason(void) -- 2.33.0