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=-9.0 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,T_DKIMWL_WL_HIGH,USER_AGENT_GIT autolearn=unavailable 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 7D609C282DD for ; Thu, 23 May 2019 19:42:25 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 55B7420881 for ; Thu, 23 May 2019 19:42:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1558640545; bh=zo4BNT2y5vGThUf1YBTI4tm47+GcKrXMdYgr+k3oHic=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=TTN3mGCTAl7DV8VID03v8ccvom6vvw7qjjlB1D2b9bKdFB0k616R4gQZ96qjfDcEn jejbmkNJFIq3m2wX0lxrwE3vXbtOs8hjPn/XruNO9hiZw0uxxe5SeNS9wpC9eDyMnX q+PqcinHVTW1j9bspEiZcftS/4Y72/H8XDmABN6A= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388670AbfEWTmU (ORCPT ); Thu, 23 May 2019 15:42:20 -0400 Received: from mail.kernel.org ([198.145.29.99]:54962 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2389747AbfEWTTI (ORCPT ); Thu, 23 May 2019 15:19:08 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (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 B15A0205ED; Thu, 23 May 2019 19:19:07 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1558639148; bh=zo4BNT2y5vGThUf1YBTI4tm47+GcKrXMdYgr+k3oHic=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=KUHS9hsMhTSISoqAsSQ1IhyM1ZB2UeGuvb93Veqcn9cLtHVCmM3FqBLWitkTTc/I3 CJBYb8rJ9fptANOclPCCm9lcmOLgyiHmE3ihtG6itMq+HvXDbcFLCEqAPGltXcGj60 nYtGuHJb7zCBVymaeiT55WQS/Q4S/aJgS3p3DDZI= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Vitaly Kuznetsov , Paolo Bonzini , Sasha Levin Subject: [PATCH 4.19 095/114] x86: kvm: hyper-v: deal with buggy TLB flush requests from WS2012 Date: Thu, 23 May 2019 21:06:34 +0200 Message-Id: <20190523181739.956056404@linuxfoundation.org> X-Mailer: git-send-email 2.21.0 In-Reply-To: <20190523181731.372074275@linuxfoundation.org> References: <20190523181731.372074275@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org [ Upstream commit da66761c2d93a46270d69001abb5692717495a68 ] It was reported that with some special Multi Processor Group configuration, e.g: bcdedit.exe /set groupsize 1 bcdedit.exe /set maxgroup on bcdedit.exe /set groupaware on for a 16-vCPU guest WS2012 shows BSOD on boot when PV TLB flush mechanism is in use. Tracing kvm_hv_flush_tlb immediately reveals the issue: kvm_hv_flush_tlb: processor_mask 0x0 address_space 0x0 flags 0x2 The only flag set in this request is HV_FLUSH_ALL_VIRTUAL_ADDRESS_SPACES, however, processor_mask is 0x0 and no HV_FLUSH_ALL_PROCESSORS is specified. We don't flush anything and apparently it's not what Windows expects. TLFS doesn't say anything about such requests and newer Windows versions seem to be unaffected. This all feels like a WS2012 bug, which is, however, easy to workaround in KVM: let's flush everything when we see an empty flush request, over-flushing doesn't hurt. Signed-off-by: Vitaly Kuznetsov Signed-off-by: Paolo Bonzini Signed-off-by: Sasha Levin --- arch/x86/kvm/hyperv.c | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-) diff --git a/arch/x86/kvm/hyperv.c b/arch/x86/kvm/hyperv.c index 01d209ab5481b..229d996051653 100644 --- a/arch/x86/kvm/hyperv.c +++ b/arch/x86/kvm/hyperv.c @@ -1291,7 +1291,16 @@ static u64 kvm_hv_flush_tlb(struct kvm_vcpu *current_vcpu, u64 ingpa, flush.address_space, flush.flags); sparse_banks[0] = flush.processor_mask; - all_cpus = flush.flags & HV_FLUSH_ALL_PROCESSORS; + + /* + * Work around possible WS2012 bug: it sends hypercalls + * with processor_mask = 0x0 and HV_FLUSH_ALL_PROCESSORS clear, + * while also expecting us to flush something and crashing if + * we don't. Let's treat processor_mask == 0 same as + * HV_FLUSH_ALL_PROCESSORS. + */ + all_cpus = (flush.flags & HV_FLUSH_ALL_PROCESSORS) || + flush.processor_mask == 0; } else { if (unlikely(kvm_read_guest(kvm, ingpa, &flush_ex, sizeof(flush_ex)))) -- 2.20.1