Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753301AbdCTIRx (ORCPT ); Mon, 20 Mar 2017 04:17:53 -0400 Received: from mail-pg0-f66.google.com ([74.125.83.66]:33567 "EHLO mail-pg0-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753257AbdCTIRS (ORCPT ); Mon, 20 Mar 2017 04:17:18 -0400 From: Kyle Huey X-Google-Original-From: Kyle Huey To: "Robert O'Callahan" , Thomas Gleixner , Andy Lutomirski , Ingo Molnar , "H. Peter Anvin" , x86@kernel.org, Paolo Bonzini , =?UTF-8?q?Radim=20Kr=C4=8Dm=C3=A1=C5=99?= , Jeff Dike , Richard Weinberger , Alexander Viro , Shuah Khan , Dave Hansen , Borislav Petkov , Peter Zijlstra , Boris Ostrovsky , Len Brown , "Rafael J. Wysocki" , Dmitry Safonov , David Matlack , Nadav Amit , Andi Kleen , Grzegorz Andrejczuk Cc: linux-kernel@vger.kernel.org, user-mode-linux-devel@lists.sourceforge.net, user-mode-linux-user@lists.sourceforge.net, linux-fsdevel@vger.kernel.org, linux-kselftest@vger.kernel.org, kvm@vger.kernel.org Subject: [PATCH v16 10/10] KVM: x86: virtualize cpuid faulting Date: Mon, 20 Mar 2017 01:16:28 -0700 Message-Id: <20170320081628.18952-11-khuey@kylehuey.com> X-Mailer: git-send-email 2.11.0 In-Reply-To: <20170320081628.18952-1-khuey@kylehuey.com> References: <20170320081628.18952-1-khuey@kylehuey.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4750 Lines: 141 Hardware support for faulting on the cpuid instruction is not required to emulate it, because cpuid triggers a VM exit anyways. KVM handles the relevant MSRs (MSR_PLATFORM_INFO and MSR_MISC_FEATURES_ENABLE) and upon a cpuid-induced VM exit checks the cpuid faulting state and the CPL. kvm_require_cpl is even kind enough to inject the GP fault for us. Signed-off-by: Kyle Huey Reviewed-by: David Matlack --- arch/x86/include/asm/kvm_host.h | 2 ++ arch/x86/kvm/cpuid.c | 3 +++ arch/x86/kvm/cpuid.h | 11 +++++++++++ arch/x86/kvm/emulate.c | 7 +++++++ arch/x86/kvm/x86.c | 26 ++++++++++++++++++++++++++ 5 files changed, 49 insertions(+) diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h index 74ef58c8ff53..df0c2bd970a4 100644 --- a/arch/x86/include/asm/kvm_host.h +++ b/arch/x86/include/asm/kvm_host.h @@ -612,6 +612,8 @@ struct kvm_vcpu_arch { unsigned long dr7; unsigned long eff_db[KVM_NR_DB_REGS]; unsigned long guest_debug_dr7; + u64 msr_platform_info; + u64 msr_misc_features_enables; u64 mcg_cap; u64 mcg_status; diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c index efde6cc50875..cb560a509041 100644 --- a/arch/x86/kvm/cpuid.c +++ b/arch/x86/kvm/cpuid.c @@ -876,6 +876,9 @@ int kvm_emulate_cpuid(struct kvm_vcpu *vcpu) { u32 eax, ebx, ecx, edx; + if (cpuid_fault_enabled(vcpu) && !kvm_require_cpl(vcpu, 0)) + return; + eax = kvm_register_read(vcpu, VCPU_REGS_RAX); ecx = kvm_register_read(vcpu, VCPU_REGS_RCX); kvm_cpuid(vcpu, &eax, &ebx, &ecx, &edx); diff --git a/arch/x86/kvm/cpuid.h b/arch/x86/kvm/cpuid.h index 35058c2c0eea..a6fd40aade7c 100644 --- a/arch/x86/kvm/cpuid.h +++ b/arch/x86/kvm/cpuid.h @@ -205,4 +205,15 @@ static inline int guest_cpuid_stepping(struct kvm_vcpu *vcpu) return x86_stepping(best->eax); } +static inline bool supports_cpuid_fault(struct kvm_vcpu *vcpu) +{ + return vcpu->arch.msr_platform_info & MSR_PLATFORM_INFO_CPUID_FAULT; +} + +static inline bool cpuid_fault_enabled(struct kvm_vcpu *vcpu) +{ + return vcpu->arch.msr_misc_features_enables & + MSR_MISC_FEATURES_ENABLES_CPUID_FAULT; +} + #endif diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c index 45c7306c8780..6a2ea945d01f 100644 --- a/arch/x86/kvm/emulate.c +++ b/arch/x86/kvm/emulate.c @@ -3854,6 +3854,13 @@ static int em_sti(struct x86_emulate_ctxt *ctxt) static int em_cpuid(struct x86_emulate_ctxt *ctxt) { u32 eax, ebx, ecx, edx; + u64 msr = 0; + + ctxt->ops->get_msr(ctxt, MSR_MISC_FEATURES_ENABLES, &msr); + if (msr & MSR_MISC_FEATURES_ENABLES_CPUID_FAULT && + ctxt->ops->cpl(ctxt)) { + return emulate_gp(ctxt, 0); + } eax = reg_read(ctxt, VCPU_REGS_RAX); ecx = reg_read(ctxt, VCPU_REGS_RCX); diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 1faf620a6fdc..16d2082d85fb 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -1008,6 +1008,8 @@ static u32 emulated_msrs[] = { MSR_IA32_MCG_CTL, MSR_IA32_MCG_EXT_CTL, MSR_IA32_SMBASE, + MSR_PLATFORM_INFO, + MSR_MISC_FEATURES_ENABLES, }; static unsigned num_emulated_msrs; @@ -2331,6 +2333,21 @@ int kvm_set_msr_common(struct kvm_vcpu *vcpu, struct msr_data *msr_info) return 1; vcpu->arch.osvw.status = data; break; + case MSR_PLATFORM_INFO: + if (!msr_info->host_initiated || + data & ~MSR_PLATFORM_INFO_CPUID_FAULT || + (!(data & MSR_PLATFORM_INFO_CPUID_FAULT) && + cpuid_fault_enabled(vcpu))) + return 1; + vcpu->arch.msr_platform_info = data; + break; + case MSR_MISC_FEATURES_ENABLES: + if (data & ~MSR_MISC_FEATURES_ENABLES_CPUID_FAULT || + (data & MSR_MISC_FEATURES_ENABLES_CPUID_FAULT && + !supports_cpuid_fault(vcpu))) + return 1; + vcpu->arch.msr_misc_features_enables = data; + break; default: if (msr && (msr == vcpu->kvm->arch.xen_hvm_config.msr)) return xen_hvm_config(vcpu, data); @@ -2545,6 +2562,12 @@ int kvm_get_msr_common(struct kvm_vcpu *vcpu, struct msr_data *msr_info) return 1; msr_info->data = vcpu->arch.osvw.status; break; + case MSR_PLATFORM_INFO: + msr_info->data = vcpu->arch.msr_platform_info; + break; + case MSR_MISC_FEATURES_ENABLES: + msr_info->data = vcpu->arch.msr_misc_features_enables; + break; default: if (kvm_pmu_is_valid_msr(vcpu, msr_info->index)) return kvm_pmu_get_msr(vcpu, msr_info->index, &msr_info->data); @@ -7724,6 +7747,9 @@ void kvm_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event) if (!init_event) { kvm_pmu_reset(vcpu); vcpu->arch.smbase = 0x30000; + + vcpu->arch.msr_platform_info = MSR_PLATFORM_INFO_CPUID_FAULT; + vcpu->arch.msr_misc_features_enables = 0; } memset(vcpu->arch.regs, 0, sizeof(vcpu->arch.regs)); -- 2.11.0