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 433A9C4167B for ; Thu, 30 Nov 2023 18:17:40 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1346207AbjK3SRb (ORCPT ); Thu, 30 Nov 2023 13:17:31 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59474 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231736AbjK3SR3 (ORCPT ); Thu, 30 Nov 2023 13:17:29 -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 ESMTPS id 54DD7D6C for ; Thu, 30 Nov 2023 10:17:36 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1701368255; 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=CrFEpIsAN5CLxammhD+GAJP9cPsbGGrmnZDHNVsmekk=; b=IRUxCG0hGwUQVZejq7gsGv1XZx/OLIprkTRxKsCmmxhIuFgYGzJKVaOSOb035pRcOivPMA z1ETQjLBCYGRTk/KoOTgwe3BY305ToBwN2hngdla+31UO5oG0w/+6MeQp5hpqJ9wAG9auI 1y0aas7erTGZLMWHZxOc4yaVZylByRI= Received: from mail-lf1-f70.google.com (mail-lf1-f70.google.com [209.85.167.70]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-547-sG5CK5UePAilhZfOe9nvHg-1; Thu, 30 Nov 2023 13:17:34 -0500 X-MC-Unique: sG5CK5UePAilhZfOe9nvHg-1 Received: by mail-lf1-f70.google.com with SMTP id 2adb3069b0e04-50bc7296f75so1415814e87.2 for ; Thu, 30 Nov 2023 10:17:33 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1701368252; x=1701973052; h=content-transfer-encoding:mime-version:user-agent:references :in-reply-to:date:cc:to:from:subject:message-id:x-gm-message-state :from:to:cc:subject:date:message-id:reply-to; bh=CrFEpIsAN5CLxammhD+GAJP9cPsbGGrmnZDHNVsmekk=; b=Y5/3Lv8z66Hgm6YbvGTZPSjw3BdBKo8o1N2DYxotBR1eemKr6Z6upfEROzD0uWusN1 oD2GGSlo0q4XWsVyJE33d0zDZQPO2UQckIXRrKfe7SomqFiUErlaIrK+t3Gg8Zt49iyH yVAQdKr8Rj0Y3t6PppmMHUX7pipb5OM382NiaWKq18VNWGKOJPu55qrr7c6Vpn/ONUYD rBvRXXkDIbLeDycO/CbvAsrhCVcsKcj7EbdiXXevyW6nWSpOihTfi1jaHoU7EFf1qjMF DG1NfHdExrmIhh8HNP20Ejz5tUOw5cK4WgImKbpW3mXm6Wn0SBiO/LYtvSYI5D+7FRZl KrgA== X-Gm-Message-State: AOJu0YyjiwxU2JDjkeWIQslLyhclah9LpOgg1udTW1rPyCxzTpchrRt9 Uf43Ed5gNSRKEzqY2WJ4/EBOJ/MQmNWIQVUiaW7XstBjwVGG6wcIAzMCr00WWhKbtkfeLxE4BaG fzYvZkroqgvynV4Lrob4/ZVVCyDAWtyXQ X-Received: by 2002:a05:6512:39c5:b0:50b:c027:70f with SMTP id k5-20020a05651239c500b0050bc027070fmr286lfu.21.1701368252298; Thu, 30 Nov 2023 10:17:32 -0800 (PST) X-Google-Smtp-Source: AGHT+IFDeqYIAaVd/veLSsPan4ItHCmZAXYpV0ezMbb4/NCI3nQ4Fjl7Bmf1Eq8wWcU569Tv8r8zRw== X-Received: by 2002:a17:906:15c:b0:9e7:8ad0:a471 with SMTP id 28-20020a170906015c00b009e78ad0a471mr171135ejh.12.1701366013091; Thu, 30 Nov 2023 09:40:13 -0800 (PST) Received: from starship ([5.28.147.32]) by smtp.gmail.com with ESMTPSA id 6-20020ac24846000000b0050bc56dd0acsm213436lfy.184.2023.11.30.09.40.10 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 30 Nov 2023 09:40:11 -0800 (PST) Message-ID: Subject: Re: [PATCH v7 17/26] KVM: x86: Report KVM supported CET MSRs as to-be-saved From: Maxim Levitsky To: Yang Weijiang , seanjc@google.com, pbonzini@redhat.com, dave.hansen@intel.com, kvm@vger.kernel.org, linux-kernel@vger.kernel.org Cc: peterz@infradead.org, chao.gao@intel.com, rick.p.edgecombe@intel.com, john.allen@amd.com Date: Thu, 30 Nov 2023 19:40:09 +0200 In-Reply-To: <20231124055330.138870-18-weijiang.yang@intel.com> References: <20231124055330.138870-1-weijiang.yang@intel.com> <20231124055330.138870-18-weijiang.yang@intel.com> Content-Type: text/plain; charset="UTF-8" User-Agent: Evolution 3.36.5 (3.36.5-2.fc32) MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 2023-11-24 at 00:53 -0500, Yang Weijiang wrote: > Add CET MSRs to the list of MSRs reported to userspace if the feature, > i.e. IBT or SHSTK, associated with the MSRs is supported by KVM. > > SSP can only be read via RDSSP. Writing even requires destructive and > potentially faulting operations such as SAVEPREVSSP/RSTORSSP or > SETSSBSY/CLRSSBSY. Let the host use a pseudo-MSR that is just a wrapper > for the GUEST_SSP field of the VMCS. > > Suggested-by: Chao Gao > Signed-off-by: Yang Weijiang > --- > arch/x86/include/uapi/asm/kvm_para.h | 1 + > arch/x86/kvm/vmx/vmx.c | 2 ++ > arch/x86/kvm/x86.c | 18 ++++++++++++++++++ > 3 files changed, 21 insertions(+) > > diff --git a/arch/x86/include/uapi/asm/kvm_para.h b/arch/x86/include/uapi/asm/kvm_para.h > index 6e64b27b2c1e..9864bbcf2470 100644 > --- a/arch/x86/include/uapi/asm/kvm_para.h > +++ b/arch/x86/include/uapi/asm/kvm_para.h > @@ -58,6 +58,7 @@ > #define MSR_KVM_ASYNC_PF_INT 0x4b564d06 > #define MSR_KVM_ASYNC_PF_ACK 0x4b564d07 > #define MSR_KVM_MIGRATION_CONTROL 0x4b564d08 > +#define MSR_KVM_SSP 0x4b564d09 > > struct kvm_steal_time { > __u64 steal; > diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c > index be20a60047b1..d3d0d74fef70 100644 > --- a/arch/x86/kvm/vmx/vmx.c > +++ b/arch/x86/kvm/vmx/vmx.c > @@ -7009,6 +7009,8 @@ static bool vmx_has_emulated_msr(struct kvm *kvm, u32 index) > case MSR_AMD64_TSC_RATIO: > /* This is AMD only. */ > return false; > + case MSR_KVM_SSP: > + return kvm_cpu_cap_has(X86_FEATURE_SHSTK); > default: > return true; > } > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c > index 44b8cf459dfc..74d2d00a1681 100644 > --- a/arch/x86/kvm/x86.c > +++ b/arch/x86/kvm/x86.c > @@ -1476,6 +1476,9 @@ static const u32 msrs_to_save_base[] = { > > MSR_IA32_XFD, MSR_IA32_XFD_ERR, > MSR_IA32_XSS, > + MSR_IA32_U_CET, MSR_IA32_S_CET, > + MSR_IA32_PL0_SSP, MSR_IA32_PL1_SSP, MSR_IA32_PL2_SSP, > + MSR_IA32_PL3_SSP, MSR_IA32_INT_SSP_TAB, > }; > > static const u32 msrs_to_save_pmu[] = { > @@ -1576,6 +1579,7 @@ static const u32 emulated_msrs_all[] = { > > MSR_K7_HWCR, > MSR_KVM_POLL_CONTROL, > + MSR_KVM_SSP, > }; > > static u32 emulated_msrs[ARRAY_SIZE(emulated_msrs_all)]; > @@ -7371,6 +7375,20 @@ static void kvm_probe_msr_to_save(u32 msr_index) > if (!kvm_caps.supported_xss) > return; > break; > + case MSR_IA32_U_CET: > + case MSR_IA32_S_CET: > + if (!kvm_cpu_cap_has(X86_FEATURE_SHSTK) && > + !kvm_cpu_cap_has(X86_FEATURE_IBT)) > + return; > + break; > + case MSR_IA32_INT_SSP_TAB: > + if (!kvm_cpu_cap_has(X86_FEATURE_LM)) > + return; > + fallthrough; > + case MSR_IA32_PL0_SSP ... MSR_IA32_PL3_SSP: > + if (!kvm_cpu_cap_has(X86_FEATURE_SHSTK)) > + return; > + break; > default: > break; > } I still think that pseudo MSR is a hack that might backfire, but I am not going to argue much about this. Best regards, Maxim Levitsky