From patchwork Tue Jun 21 15:08:56 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Maxim Levitsky X-Patchwork-Id: 12889383 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 7F942C43334 for ; Tue, 21 Jun 2022 15:09:47 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1352317AbiFUPJq (ORCPT ); Tue, 21 Jun 2022 11:09:46 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44082 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1352298AbiFUPJo (ORCPT ); Tue, 21 Jun 2022 11:09:44 -0400 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 5B5D027FF9 for ; Tue, 21 Jun 2022 08:09:36 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1655824175; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=iKMJAOMUnqojm6f+PSfvuxFpiYCb8Fg7PQ9tT8zsGYc=; b=agdHOcDXdDsuVs1HBLaD4OptKLURahy5LVCNfXByprGOQLowM5KgzNEJkjrmr6RaUKI+Ec Jld5KLOggigI3/QZbOJ46eMhs/Hmq4UydafJEpP3PY0nFbBYlGPn4UTcCaZEPCJusVoxT0 xw2G+kFJgbcCjl9KIYjmx63OFTMb7+A= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-445-WnP0U4rHOa-85xVkzuFcJw-1; Tue, 21 Jun 2022 11:09:28 -0400 X-MC-Unique: WnP0U4rHOa-85xVkzuFcJw-1 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.rdu2.redhat.com [10.11.54.5]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 4C0011044564; Tue, 21 Jun 2022 15:09:27 +0000 (UTC) Received: from localhost.localdomain (unknown [10.40.194.180]) by smtp.corp.redhat.com (Postfix) with ESMTP id 9BEC818EA3; Tue, 21 Jun 2022 15:09:23 +0000 (UTC) From: Maxim Levitsky To: kvm@vger.kernel.org Cc: Sean Christopherson , x86@kernel.org, Kees Cook , Dave Hansen , linux-kernel@vger.kernel.org, "H. Peter Anvin" , Borislav Petkov , Joerg Roedel , Ingo Molnar , Paolo Bonzini , Thomas Gleixner , Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Maxim Levitsky Subject: [PATCH v2 05/11] KVM: x86: emulator: update the emulation mode after CR0 write Date: Tue, 21 Jun 2022 18:08:56 +0300 Message-Id: <20220621150902.46126-6-mlevitsk@redhat.com> In-Reply-To: <20220621150902.46126-1-mlevitsk@redhat.com> References: <20220621150902.46126-1-mlevitsk@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.11.54.5 Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org CR0.PE toggles real/protected mode, thus its update should update the emulation mode. This is likely a benign bug because there is no writeback of state, other than the RIP increment, and when toggling CR0.PE, the CPU has to execute code from a very low memory address. Signed-off-by: Maxim Levitsky --- arch/x86/kvm/emulate.c | 13 ++++++++++++- 1 file changed, 12 insertions(+), 1 deletion(-) diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c index 6f4632babc4cd8..002687d17f9364 100644 --- a/arch/x86/kvm/emulate.c +++ b/arch/x86/kvm/emulate.c @@ -3659,11 +3659,22 @@ static int em_movbe(struct x86_emulate_ctxt *ctxt) static int em_cr_write(struct x86_emulate_ctxt *ctxt) { - if (ctxt->ops->set_cr(ctxt, ctxt->modrm_reg, ctxt->src.val)) + int cr_num = ctxt->modrm_reg; + int r; + + if (ctxt->ops->set_cr(ctxt, cr_num, ctxt->src.val)) return emulate_gp(ctxt, 0); /* Disable writeback. */ ctxt->dst.type = OP_NONE; + + if (cr_num == 0) { + /* CR0 write might have updated CR0.PE */ + r = update_emulation_mode(ctxt); + if (r != X86EMUL_CONTINUE) + return r; + } + return X86EMUL_CONTINUE; }