From patchwork Wed Aug 3 15:50:03 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Maxim Levitsky X-Patchwork-Id: 12935618 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 EEF96C19F28 for ; Wed, 3 Aug 2022 15:51:09 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237726AbiHCPvI (ORCPT ); Wed, 3 Aug 2022 11:51:08 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50074 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S238317AbiHCPuv (ORCPT ); Wed, 3 Aug 2022 11:50:51 -0400 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 22A8FBCB6 for ; Wed, 3 Aug 2022 08:50:44 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1659541843; 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=LmwB0r7xATrpDyRlyUFgvOk4mUnvm3hP8rUm/cmUZV8=; b=KEJbekhtR/XqmhQY0sETXiS3JicF3L0nmCTo7TE9+ktsKvsX66Jolsyo4E2g3b525Pu02V MFEj8nloJMasvoUcqyB89PXA/nN0VQDrUuFg6DrrIcqMaWYCaAierrrPBUST3l6kL2b3eg qODmNiN5p2CID2P5Ud8FsUP3uZU6JKs= Received: from mimecast-mx02.redhat.com (mx3-rdu2.redhat.com [66.187.233.73]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-408-XCfdXdIDMCOVUNhfW_Rq0A-1; Wed, 03 Aug 2022 11:50:39 -0400 X-MC-Unique: XCfdXdIDMCOVUNhfW_Rq0A-1 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.rdu2.redhat.com [10.11.54.3]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 3AD7D3C0D841; Wed, 3 Aug 2022 15:50:38 +0000 (UTC) Received: from localhost.localdomain (unknown [10.40.194.242]) by smtp.corp.redhat.com (Postfix) with ESMTP id 991C11121315; Wed, 3 Aug 2022 15:50:34 +0000 (UTC) From: Maxim Levitsky To: kvm@vger.kernel.org Cc: Borislav Petkov , Dave Hansen , linux-kernel@vger.kernel.org, Wanpeng Li , Maxim Levitsky , Ingo Molnar , Sean Christopherson , x86@kernel.org, Jim Mattson , Kees Cook , Thomas Gleixner , "H. Peter Anvin" , Joerg Roedel , Vitaly Kuznetsov , Paolo Bonzini Subject: [PATCH v3 05/13] KVM: x86: emulator: update the emulation mode after CR0 write Date: Wed, 3 Aug 2022 18:50:03 +0300 Message-Id: <20220803155011.43721-6-mlevitsk@redhat.com> In-Reply-To: <20220803155011.43721-1-mlevitsk@redhat.com> References: <20220803155011.43721-1-mlevitsk@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.78 on 10.11.54.3 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. Also CR0.PG toggle when EFER.LMA is set, toggles the long mode. Signed-off-by: Maxim Levitsky --- arch/x86/kvm/emulate.c | 14 +++++++++++++- 1 file changed, 13 insertions(+), 1 deletion(-) diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c index 5e91b26cc1d8aa..765ec65b2861ba 100644 --- a/arch/x86/kvm/emulate.c +++ b/arch/x86/kvm/emulate.c @@ -3658,11 +3658,23 @@ 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 execution mode */ + r = emulator_recalc_and_set_mode(ctxt); + if (r != X86EMUL_CONTINUE) + return r; + } + return X86EMUL_CONTINUE; }