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 50084C433F5 for ; Fri, 25 Feb 2022 15:07:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S240060AbiBYPIX (ORCPT ); Fri, 25 Feb 2022 10:08:23 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50366 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231767AbiBYPIT (ORCPT ); Fri, 25 Feb 2022 10:08:19 -0500 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 196175F8DD for ; Fri, 25 Feb 2022 07:07:45 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1645801664; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=ZXzg+KGWwllNSUCsWeeWB7MRsMJhSltnLNe0hU0M5/I=; b=Rd2cejM8e3m/g/pQCfrWLF37/svv9CZbY9EpslhY2Mld5gvrsU4aOQx6QGkxzakFMbeQSe 5bbAs+RBk4v8HZUc1gGlv/l8bQtEXnyitN9sls8rZ4bAi1hXXZA00O9henpfI0we+Thve4 2kdC0QQvX0oE/CNG6JTtEy+fd45ROfI= Received: from mail-wr1-f70.google.com (mail-wr1-f70.google.com [209.85.221.70]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-451-S9f_2QIBNVaTvWwzPoRLlg-1; Fri, 25 Feb 2022 10:07:42 -0500 X-MC-Unique: S9f_2QIBNVaTvWwzPoRLlg-1 Received: by mail-wr1-f70.google.com with SMTP id u9-20020adfae49000000b001e89793bcb0so987512wrd.17 for ; Fri, 25 Feb 2022 07:07:42 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:message-id:date:mime-version:user-agent:subject :content-language:to:cc:references:from:in-reply-to :content-transfer-encoding; bh=ZXzg+KGWwllNSUCsWeeWB7MRsMJhSltnLNe0hU0M5/I=; b=uq3FzSXHPd8sw0nVuN1Bdr/p/3Lii73qi4JyI9R+QMTtJ75gijqR7JvGmHDpqlhKt+ 4oX+kyc/p4qxXNPF4SE2CxAwpqEAfgJ5uA1M5WRQYFE3a1QaTwzq2UZTlIZ1sGKEQ9PJ vtBLp0pkWyj3XcqrTPK1Xv3RdP9gogicoLxCCRWlIlPZ9dKU+Is7dpeIS71wP+obMW5H m0i7Km9CwGpuoPEAQI+QdEQO970bC0WQWAuFNzK8vsMgBEYS8vAQYOD+ovNcSu28OHC1 eb1chqPyZ4KvgWcL1rUmjxcGnu06MqU7iR3mOvtmU3dUuntLwklrtz18mjMRSFkeRC+o GQaA== X-Gm-Message-State: AOAM531U6K0DxwprwUrPG+Fnzo8FoP9e/mstX1/PQds9+BZGjweCALuo oQC4lb/YxgYtrf9uPLCF5/xvweqACvzU8FtWjvOSO5UZgGQsiBvS2P/qbKK3ohA/fdjaEpIKHDH 4oSuZ6osjbz57DH41DK6JV96h X-Received: by 2002:a05:600c:500a:b0:37b:ec27:1a2c with SMTP id n10-20020a05600c500a00b0037bec271a2cmr3059013wmr.179.1645801661629; Fri, 25 Feb 2022 07:07:41 -0800 (PST) X-Google-Smtp-Source: ABdhPJxrSki4Vsp6ZUikRWQRUZNBuGhi0p8ZD93QRZt7+iDH2WTTx9q7DHDK2VxAukY6SBi8ZBxrJw== X-Received: by 2002:a05:600c:500a:b0:37b:ec27:1a2c with SMTP id n10-20020a05600c500a00b0037bec271a2cmr3058983wmr.179.1645801661377; Fri, 25 Feb 2022 07:07:41 -0800 (PST) Received: from ?IPV6:2001:b07:6468:f312:c8dd:75d4:99ab:290a? ([2001:b07:6468:f312:c8dd:75d4:99ab:290a]) by smtp.googlemail.com with ESMTPSA id f17-20020adffcd1000000b001edbf438d83sm2559168wrs.32.2022.02.25.07.07.40 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 25 Feb 2022 07:07:40 -0800 (PST) Message-ID: <4896c092-a5cb-7ed0-a5d0-32b3abc352c4@redhat.com> Date: Fri, 25 Feb 2022 16:07:39 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.5.0 Subject: Re: [PATCH v2 3/3] KVM: x86/emulator: Move the unhandled outer privilege level logic of far return into __load_segment_descriptor() Content-Language: en-US To: Hou Wenlong , kvm@vger.kernel.org Cc: Sean Christopherson , Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Joerg Roedel , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org, "H. Peter Anvin" , linux-kernel@vger.kernel.org References: <5b7188e6388ac9f4567d14eab32db9adf3e00119.1644292363.git.houwenlong.hwl@antgroup.com> From: Paolo Bonzini In-Reply-To: <5b7188e6388ac9f4567d14eab32db9adf3e00119.1644292363.git.houwenlong.hwl@antgroup.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2/8/22 10:34, Hou Wenlong wrote: > Outer-privilege level return is not implemented in emulator, > move the unhandled logic into __load_segment_descriptor to > make it easier to understand why the checks for RET are > incomplete. > > Suggested-by: Sean Christopherson > Signed-off-by: Hou Wenlong > --- > arch/x86/kvm/emulate.c | 14 ++++++++------ > 1 file changed, 8 insertions(+), 6 deletions(-) > > diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c > index 37c4213bdcc1..bd91b952eb0a 100644 > --- a/arch/x86/kvm/emulate.c > +++ b/arch/x86/kvm/emulate.c > @@ -1631,9 +1631,14 @@ static int __load_segment_descriptor(struct x86_emulate_ctxt *ctxt, > if (!(seg_desc.type & 8)) > goto exception; > > - /* RET can never return to an inner privilege level. */ > - if (transfer == X86_TRANSFER_RET && rpl < cpl) > - goto exception; > + if (transfer == X86_TRANSFER_RET) { > + /* RET can never return to an inner privilege level. */ > + if (rpl < cpl) > + goto exception; > + /* Outer-privilege level return is not implemented */ > + if (rpl > cpl) > + return X86EMUL_UNHANDLEABLE; > + } > if (transfer == X86_TRANSFER_RET || transfer == X86_TRANSFER_TASK_SWITCH) { > if (seg_desc.type & 4) { > /* conforming */ > @@ -2228,9 +2233,6 @@ static int em_ret_far(struct x86_emulate_ctxt *ctxt) > rc = emulate_pop(ctxt, &cs, ctxt->op_bytes); > if (rc != X86EMUL_CONTINUE) > return rc; > - /* Outer-privilege level return is not implemented */ > - if (ctxt->mode >= X86EMUL_MODE_PROT16 && (cs & 3) > cpl) > - return X86EMUL_UNHANDLEABLE; > rc = __load_segment_descriptor(ctxt, (u16)cs, VCPU_SREG_CS, cpl, > X86_TRANSFER_RET, > &new_desc); Queued all three, thanks! Paolo