From patchwork Tue Oct 25 12:42:13 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Maxim Levitsky X-Patchwork-Id: 13019179 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 C6ECAC04A95 for ; Tue, 25 Oct 2022 12:46:07 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232380AbiJYMqG (ORCPT ); Tue, 25 Oct 2022 08:46:06 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40704 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232227AbiJYMpr (ORCPT ); Tue, 25 Oct 2022 08:45:47 -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 ESMTPS id C419618E72C for ; Tue, 25 Oct 2022 05:44:02 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1666701838; 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=kk/y1Rqm9RfxugisprCGRVnRUEBSsRi9Ufn2Nn2BGLY=; b=fzTiQ5jFc1DMo347V/qzBnomwyLgtVawfRIPLH1maUZMmJHX2uJmluY/qJcE6KYDjic9Ot nRc1TZWbpabNOlQgjXkcfcH5Sh+g2ldUDwe+60pdB77DWTY7xaJnaH/KrL29huOLkuZ9Hh jRKvkVzZ9IC14xdqDtEZn3pkz0G5GfE= 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-497-9Ctnj63mNuaC3Obps1YDFw-1; Tue, 25 Oct 2022 08:43:55 -0400 X-MC-Unique: 9Ctnj63mNuaC3Obps1YDFw-1 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.rdu2.redhat.com [10.11.54.4]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 9A58C85A59D; Tue, 25 Oct 2022 12:43:20 +0000 (UTC) Received: from amdlaptop.tlv.redhat.com (dhcp-4-238.tlv.redhat.com [10.35.4.238]) by smtp.corp.redhat.com (Postfix) with ESMTP id 00BB520290A2; Tue, 25 Oct 2022 12:43:11 +0000 (UTC) From: Maxim Levitsky To: kvm@vger.kernel.org Cc: Paolo Bonzini , Yang Zhong , linux-kselftest@vger.kernel.org, Kees Cook , Borislav Petkov , Guang Zeng , Wanpeng Li , Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , Maxim Levitsky , Joerg Roedel , linux-kernel@vger.kernel.org, Wei Wang , Jim Mattson , Dave Hansen , Sean Christopherson , Vitaly Kuznetsov , x86@kernel.org, Shuah Khan Subject: [PATCH v4 13/23] KVM: x86: emulator: update the emulation mode after CR0 write Date: Tue, 25 Oct 2022 15:42:13 +0300 Message-Id: <20221025124223.227577-14-mlevitsk@redhat.com> In-Reply-To: <20221025124223.227577-1-mlevitsk@redhat.com> References: <20221025124223.227577-1-mlevitsk@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.1 on 10.11.54.4 Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org Update the emulation mode when handling writes to CR0, because toggling CR0.PE switches between Real and Protected Mode, and toggling CR0.PG when EFER.LME=1 switches between Long and Protected 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 | 16 +++++++++++++++- 1 file changed, 15 insertions(+), 1 deletion(-) diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c index 2c56d08b426065..5cc3efa0e21c17 100644 --- a/arch/x86/kvm/emulate.c +++ b/arch/x86/kvm/emulate.c @@ -3290,11 +3290,25 @@ 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 and/or CR0.PG + * which can affect the cpu's execution mode. + */ + r = emulator_recalc_and_set_mode(ctxt); + if (r != X86EMUL_CONTINUE) + return r; + } + return X86EMUL_CONTINUE; }