From patchwork Mon Jan 18 03:28:29 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Huang, Kai" X-Patchwork-Id: 12026341 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=-16.7 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham 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 0D375C433DB for ; Mon, 18 Jan 2021 03:29:58 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D896E224B1 for ; Mon, 18 Jan 2021 03:29:57 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731702AbhARD3y (ORCPT ); Sun, 17 Jan 2021 22:29:54 -0500 Received: from mga12.intel.com ([192.55.52.136]:16939 "EHLO mga12.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731692AbhARD3x (ORCPT ); Sun, 17 Jan 2021 22:29:53 -0500 IronPort-SDR: r0LSn1NakH0NsReBWcPWkrfvWBZYYgdRz2wpGh/7Av3utxbHUmr43igIeDUAqMt1aCimFFWscF h+HZosI0l+QQ== X-IronPort-AV: E=McAfee;i="6000,8403,9867"; a="157933903" X-IronPort-AV: E=Sophos;i="5.79,355,1602572400"; d="scan'208";a="157933903" Received: from fmsmga005.fm.intel.com ([10.253.24.32]) by fmsmga106.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 17 Jan 2021 19:29:02 -0800 IronPort-SDR: rVHi8x3Cbzgiyk4M6c9Rw1NZgIo3vxQFme11MY1gvOP3NUdUb56OLYsZJKJon5ty62Y/fnfgXr hqos1HziTwNA== X-IronPort-AV: E=Sophos;i="5.79,355,1602572400"; d="scan'208";a="573151110" Received: from amrahman-mobl.amr.corp.intel.com (HELO khuang2-desk.gar.corp.intel.com) ([10.252.142.253]) by fmsmga005-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 17 Jan 2021 19:28:58 -0800 From: Kai Huang To: linux-sgx@vger.kernel.org, kvm@vger.kernel.org, x86@kernel.org Cc: seanjc@google.com, jarkko@kernel.org, luto@kernel.org, dave.hansen@intel.com, haitao.huang@intel.com, pbonzini@redhat.com, bp@alien8.de, tglx@linutronix.de, mingo@redhat.com, hpa@zytor.com, jmattson@google.com, joro@8bytes.org, vkuznets@redhat.com, wanpengli@tencent.com, Kai Huang Subject: [RFC PATCH v2 18/26] KVM: x86: Add support for reverse CPUID lookup of scattered features Date: Mon, 18 Jan 2021 16:28:29 +1300 Message-Id: <5aea48bc36c55a633b76536515f9e888e9e54423.1610935432.git.kai.huang@intel.com> X-Mailer: git-send-email 2.29.2 In-Reply-To: References: MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-sgx@vger.kernel.org From: Sean Christopherson Introduce a scheme that allows KVM's CPUID magic to support features that are scattered in the kernel's feature words. To advertise and/or query guest support for CPUID-based features, KVM requires the bit number of an X86_FEATURE_* to match the bit number in its associated CPUID entry. For scattered features, this does not hold true. Add a framework to allow defining KVM-only words, stored in kvm_cpu_caps after the shared kernel caps, that can be used to gather the scattered feature bits by translating X86_FEATURE_* flags into their KVM-defined feature. Note, because reverse_cpuid_check() effectively forces kvm_cpu_caps lookups to be resolved at compile time, there is no runtime cost for translating from kernel-defined to kvm-defined features. More details here: https://lkml.kernel.org/r/X/jxCOLG+HUO4QlZ@google.com Signed-off-by: Sean Christopherson Signed-off-by: Kai Huang --- arch/x86/kvm/cpuid.c | 32 +++++++++++++++++++++++++++----- arch/x86/kvm/cpuid.h | 39 ++++++++++++++++++++++++++++++++++----- 2 files changed, 61 insertions(+), 10 deletions(-) diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c index 13036cf0b912..f8037fab8950 100644 --- a/arch/x86/kvm/cpuid.c +++ b/arch/x86/kvm/cpuid.c @@ -28,7 +28,7 @@ * Unlike "struct cpuinfo_x86.x86_capability", kvm_cpu_caps doesn't need to be * aligned to sizeof(unsigned long) because it's not accessed via bitops. */ -u32 kvm_cpu_caps[NCAPINTS] __read_mostly; +u32 kvm_cpu_caps[NR_KVM_CPU_CAPS] __read_mostly; EXPORT_SYMBOL_GPL(kvm_cpu_caps); static u32 xstate_required_size(u64 xstate_bv, bool compacted) @@ -53,6 +53,7 @@ static u32 xstate_required_size(u64 xstate_bv, bool compacted) } #define F feature_bit +#define SF(name) (boot_cpu_has(X86_FEATURE_##name) ? F(name) : 0) static inline struct kvm_cpuid_entry2 *cpuid_entry2_find( struct kvm_cpuid_entry2 *entries, int nent, u32 function, u32 index) @@ -331,13 +332,13 @@ int kvm_vcpu_ioctl_get_cpuid2(struct kvm_vcpu *vcpu, return r; } -static __always_inline void kvm_cpu_cap_mask(enum cpuid_leafs leaf, u32 mask) +/* Mask kvm_cpu_caps for @leaf with the raw CPUID capabilities of this CPU. */ +static __always_inline void __kvm_cpu_cap_mask(enum cpuid_leafs leaf) { const struct cpuid_reg cpuid = x86_feature_cpuid(leaf * 32); struct kvm_cpuid_entry2 entry; reverse_cpuid_check(leaf); - kvm_cpu_caps[leaf] &= mask; cpuid_count(cpuid.function, cpuid.index, &entry.eax, &entry.ebx, &entry.ecx, &entry.edx); @@ -345,6 +346,26 @@ static __always_inline void kvm_cpu_cap_mask(enum cpuid_leafs leaf, u32 mask) kvm_cpu_caps[leaf] &= *__cpuid_entry_get_reg(&entry, cpuid.reg); } +static __always_inline void kvm_cpu_cap_mask(enum cpuid_leafs leaf, u32 mask) +{ + /* Use the "init" variant for scattered leafs. */ + BUILD_BUG_ON(leaf >= NCAPINTS); + + kvm_cpu_caps[leaf] &= mask; + + __kvm_cpu_cap_mask(leaf); +} + +static __always_inline void kvm_cpu_cap_init(enum cpuid_leafs leaf, u32 mask) +{ + /* Use the "mask" variant for hardwared-defined leafs. */ + BUILD_BUG_ON(leaf < NCAPINTS); + + kvm_cpu_caps[leaf] = mask; + + __kvm_cpu_cap_mask(leaf); +} + void kvm_set_cpu_caps(void) { unsigned int f_nx = is_efer_nx() ? F(NX) : 0; @@ -355,12 +376,13 @@ void kvm_set_cpu_caps(void) unsigned int f_gbpages = 0; unsigned int f_lm = 0; #endif + memset(kvm_cpu_caps, 0, sizeof(kvm_cpu_caps)); - BUILD_BUG_ON(sizeof(kvm_cpu_caps) > + BUILD_BUG_ON(sizeof(kvm_cpu_caps) - (NKVMCAPINTS * sizeof(*kvm_cpu_caps)) > sizeof(boot_cpu_data.x86_capability)); memcpy(&kvm_cpu_caps, &boot_cpu_data.x86_capability, - sizeof(kvm_cpu_caps)); + sizeof(kvm_cpu_caps) - (NKVMCAPINTS * sizeof(*kvm_cpu_caps))); kvm_cpu_cap_mask(CPUID_1_ECX, /* diff --git a/arch/x86/kvm/cpuid.h b/arch/x86/kvm/cpuid.h index dc921d76e42e..2041e2f07347 100644 --- a/arch/x86/kvm/cpuid.h +++ b/arch/x86/kvm/cpuid.h @@ -7,7 +7,20 @@ #include #include -extern u32 kvm_cpu_caps[NCAPINTS] __read_mostly; +/* + * Hardware-defined CPUID leafs that are scattered in the kernel, but need to + * be directly used by KVM. Note, these word values conflict with the kernel's + * "bug" caps, but KVM doesn't use those. + */ +enum kvm_only_cpuid_leafs { + NR_KVM_CPU_CAPS = NCAPINTS, + + NKVMCAPINTS = NR_KVM_CPU_CAPS - NCAPINTS, +}; + +#define X86_KVM_FEATURE(w, f) ((w)*32 + (f)) + +extern u32 kvm_cpu_caps[NR_KVM_CPU_CAPS] __read_mostly; void kvm_set_cpu_caps(void); void kvm_update_cpuid_runtime(struct kvm_vcpu *vcpu); @@ -83,6 +96,20 @@ static __always_inline void reverse_cpuid_check(unsigned int x86_leaf) BUILD_BUG_ON(reverse_cpuid[x86_leaf].function == 0); } +/* + * Translate feature bits that are scattered in the kernel's cpufeatures word + * into KVM feature words that align with hardware's definitions. + */ +static __always_inline u32 __feature_translate(int x86_feature) +{ + return x86_feature; +} + +static __always_inline u32 __feature_leaf(int x86_feature) +{ + return __feature_translate(x86_feature) / 32; +} + /* * Retrieve the bit mask from an X86_FEATURE_* definition. Features contain * the hardware defined bit number (stored in bits 4:0) and a software defined @@ -91,6 +118,8 @@ static __always_inline void reverse_cpuid_check(unsigned int x86_leaf) */ static __always_inline u32 __feature_bit(int x86_feature) { + x86_feature = __feature_translate(x86_feature); + reverse_cpuid_check(x86_feature / 32); return 1 << (x86_feature & 31); } @@ -99,7 +128,7 @@ static __always_inline u32 __feature_bit(int x86_feature) static __always_inline struct cpuid_reg x86_feature_cpuid(unsigned int x86_feature) { - unsigned int x86_leaf = x86_feature / 32; + unsigned int x86_leaf = __feature_leaf(x86_feature); reverse_cpuid_check(x86_leaf); return reverse_cpuid[x86_leaf]; @@ -291,7 +320,7 @@ static inline bool cpuid_fault_enabled(struct kvm_vcpu *vcpu) static __always_inline void kvm_cpu_cap_clear(unsigned int x86_feature) { - unsigned int x86_leaf = x86_feature / 32; + unsigned int x86_leaf = __feature_leaf(x86_feature); reverse_cpuid_check(x86_leaf); kvm_cpu_caps[x86_leaf] &= ~__feature_bit(x86_feature); @@ -299,7 +328,7 @@ static __always_inline void kvm_cpu_cap_clear(unsigned int x86_feature) static __always_inline void kvm_cpu_cap_set(unsigned int x86_feature) { - unsigned int x86_leaf = x86_feature / 32; + unsigned int x86_leaf = __feature_leaf(x86_feature); reverse_cpuid_check(x86_leaf); kvm_cpu_caps[x86_leaf] |= __feature_bit(x86_feature); @@ -307,7 +336,7 @@ static __always_inline void kvm_cpu_cap_set(unsigned int x86_feature) static __always_inline u32 kvm_cpu_cap_get(unsigned int x86_feature) { - unsigned int x86_leaf = x86_feature / 32; + unsigned int x86_leaf = __feature_leaf(x86_feature); reverse_cpuid_check(x86_leaf); return kvm_cpu_caps[x86_leaf] & __feature_bit(x86_feature);