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=-17.5 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,NICE_REPLY_A, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 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 00528C433DB for ; Thu, 28 Jan 2021 17:44:59 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A9FDD64E17 for ; Thu, 28 Jan 2021 17:44:58 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233208AbhA1Roe (ORCPT ); Thu, 28 Jan 2021 12:44:34 -0500 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:34919 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233074AbhA1RoF (ORCPT ); Thu, 28 Jan 2021 12:44:05 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1611855757; 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=xJS+3GFCtCfmN69c0BzqEjKIwA/fcAY9rImqkPB5gBQ=; b=BpQRu5l4ien9mf33VYQvh4SF0DWRUq5r+AqRmOQ2z/9Vdln7AsK+A/QfUBmYi8G7tWyhlf MjkvX/9HtJ44i2KMSpKQ8NtyMo+QbClEm6coOEBJyrK+Jy+4xQFhwEr+wJykFPrwSY5QPK QQRlgM0XWV81RLO2QhoCJ5zCZ0bEu80= Received: from mail-ej1-f72.google.com (mail-ej1-f72.google.com [209.85.218.72]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-181-TEoXBi5FNFaAnl7VBfZszw-1; Thu, 28 Jan 2021 12:42:36 -0500 X-MC-Unique: TEoXBi5FNFaAnl7VBfZszw-1 Received: by mail-ej1-f72.google.com with SMTP id le12so2526100ejb.13 for ; Thu, 28 Jan 2021 09:42:35 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:cc:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=xJS+3GFCtCfmN69c0BzqEjKIwA/fcAY9rImqkPB5gBQ=; b=GaIGhOQ7dJs0AnY2uAN8CQhZKG3/Qdo6oI53DSFVUeURvdmc+sUj0QWy8gWfp5poWn 0uY6vg8yUszfjCePRCPIEvk5s1biBs2nkfTU9u0KiFXySSCpQsh+s8KhoRwAJsV5rjxV O94X4AEZZcuv9rXMyl7wqoE33B/RMdlBRMF1638refZsH+lTLmDqfTOeZUiOKPZDvRio S+HZMcYSrbU2RRNbndSuxYpoD4r/06jyK6FMleGC9eyt/vzaOAa328nIndQ1IhrCeo0u ArGJ88OXpQkRn/2Nn5UrwPg0nKA8SvE5Nb/x2a8IRi7OkihzEkrZx5FEH1gzK9AKZV+J 71Pg== X-Gm-Message-State: AOAM530x0DAMzVK1iIVe8obxYyTH92fr4TM5FEN2KYYM3eWYbdDQxYso AbgZiM0iJZvE9L8so4yFUNFv98v6BjpFcgSljoTT3gj2AyiIVLsean8bdwCsPEa8q7OScClOE2x UTDpx5GagO0TL X-Received: by 2002:a05:6402:3487:: with SMTP id v7mr814648edc.68.1611855754985; Thu, 28 Jan 2021 09:42:34 -0800 (PST) X-Google-Smtp-Source: ABdhPJzrN8Ed0JfsjIGJTjYBE38cLR12dA3PUS54cDu+Mv1wdeKrexLUMtwsnv/jahIBOMJlz8hpYw== X-Received: by 2002:a05:6402:3487:: with SMTP id v7mr814625edc.68.1611855754788; Thu, 28 Jan 2021 09:42:34 -0800 (PST) Received: from ?IPv6:2001:b07:6468:f312:c8dd:75d4:99ab:290a? ([2001:b07:6468:f312:c8dd:75d4:99ab:290a]) by smtp.gmail.com with ESMTPSA id p12sm3437911edr.82.2021.01.28.09.42.32 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 28 Jan 2021 09:42:33 -0800 (PST) Subject: Re: [PATCH v14 08/13] KVM: VMX: Add a synthetic MSR to allow userspace VMM to access GUEST_SSP To: Yang Weijiang , kvm@vger.kernel.org, linux-kernel@vger.kernel.org, sean.j.christopherson@intel.com, jmattson@google.com Cc: yu.c.zhang@linux.intel.com References: <20201106011637.14289-1-weijiang.yang@intel.com> <20201106011637.14289-9-weijiang.yang@intel.com> From: Paolo Bonzini Message-ID: Date: Thu, 28 Jan 2021 18:42:31 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.6.0 MIME-Version: 1.0 In-Reply-To: <20201106011637.14289-9-weijiang.yang@intel.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On 06/11/20 02:16, Yang Weijiang wrote: > Introduce a host-only synthetic MSR, MSR_KVM_GUEST_SSP so that the VMM > can read/write the guest's SSP, e.g. to migrate CET state. Use a > synthetic MSR, e.g. as opposed to a VCPU_REG_, as GUEST_SSP is subject > to the same consistency checks as the PL*_SSP MSRs, i.e. can share code. > > Co-developed-by: Sean Christopherson > Signed-off-by: Sean Christopherson > Signed-off-by: Yang Weijiang > --- > arch/x86/include/uapi/asm/kvm_para.h | 1 + > arch/x86/kvm/vmx/vmx.c | 14 ++++++++++++-- > 2 files changed, 13 insertions(+), 2 deletions(-) > > diff --git a/arch/x86/include/uapi/asm/kvm_para.h b/arch/x86/include/uapi/asm/kvm_para.h > index 812e9b4c1114..5203dc084125 100644 > --- a/arch/x86/include/uapi/asm/kvm_para.h > +++ b/arch/x86/include/uapi/asm/kvm_para.h > @@ -53,6 +53,7 @@ > #define MSR_KVM_POLL_CONTROL 0x4b564d05 > #define MSR_KVM_ASYNC_PF_INT 0x4b564d06 > #define MSR_KVM_ASYNC_PF_ACK 0x4b564d07 > +#define MSR_KVM_GUEST_SSP 0x4b564d08 > > struct kvm_steal_time { > __u64 steal; > diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c > index dd78d3a79e79..28ba8414a7a3 100644 > --- a/arch/x86/kvm/vmx/vmx.c > +++ b/arch/x86/kvm/vmx/vmx.c > @@ -1817,7 +1817,8 @@ static bool cet_is_ssp_msr_accessible(struct kvm_vcpu *vcpu, > if (msr->host_initiated) > return true; > > - if (!guest_cpuid_has(vcpu, X86_FEATURE_SHSTK)) > + if (!guest_cpuid_has(vcpu, X86_FEATURE_SHSTK) || > + msr->index == MSR_KVM_GUEST_SSP) > return false; > > if (msr->index == MSR_IA32_INT_SSP_TAB) > @@ -1995,6 +1996,11 @@ static int vmx_get_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info) > return 1; > msr_info->data = vmcs_readl(GUEST_INTR_SSP_TABLE); > break; > + case MSR_KVM_GUEST_SSP: > + if (!cet_is_ssp_msr_accessible(vcpu, msr_info)) > + return 1; > + msr_info->data = vmcs_readl(GUEST_SSP); > + break; > case MSR_IA32_PL0_SSP ... MSR_IA32_PL3_SSP: > if (!cet_is_ssp_msr_accessible(vcpu, msr_info)) > return 1; > @@ -2287,12 +2293,16 @@ static int vmx_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info) > return 1; > vmcs_writel(GUEST_INTR_SSP_TABLE, data); > break; > + case MSR_KVM_GUEST_SSP: > case MSR_IA32_PL0_SSP ... MSR_IA32_PL3_SSP: > if (!cet_is_ssp_msr_accessible(vcpu, msr_info)) > return 1; > if ((data & GENMASK(2, 0)) || is_noncanonical_address(data, vcpu)) > return 1; > - vmx_set_xsave_msr(msr_info); > + if (msr_index == MSR_KVM_GUEST_SSP) > + vmcs_writel(GUEST_SSP, data); > + else > + vmx_set_xsave_msr(msr_info); > break; > case MSR_TSC_AUX: > if (!msr_info->host_initiated && > Doh, I misread the change in cet_is_ssp_msr_accessible, sorry. */