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=-9.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, USER_AGENT_GIT 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 C2037C3F2D1 for ; Tue, 3 Mar 2020 00:01:57 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 9A38724677 for ; Tue, 3 Mar 2020 00:01:57 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727276AbgCBX5Z (ORCPT ); Mon, 2 Mar 2020 18:57:25 -0500 Received: from mga03.intel.com ([134.134.136.65]:17168 "EHLO mga03.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727101AbgCBX5Z (ORCPT ); Mon, 2 Mar 2020 18:57:25 -0500 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga006.jf.intel.com ([10.7.209.51]) by orsmga103.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 02 Mar 2020 15:57:23 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.70,509,1574150400"; d="scan'208";a="243384768" Received: from sjchrist-coffee.jf.intel.com ([10.54.74.202]) by orsmga006.jf.intel.com with ESMTP; 02 Mar 2020 15:57:23 -0800 From: Sean Christopherson To: Paolo Bonzini Cc: Sean Christopherson , Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Joerg Roedel , kvm@vger.kernel.org, linux-kernel@vger.kernel.org, Xiaoyao Li Subject: [PATCH v2 48/66] KVM: x86: Remove stateful CPUID handling Date: Mon, 2 Mar 2020 15:56:51 -0800 Message-Id: <20200302235709.27467-49-sean.j.christopherson@intel.com> X-Mailer: git-send-email 2.24.1 In-Reply-To: <20200302235709.27467-1-sean.j.christopherson@intel.com> References: <20200302235709.27467-1-sean.j.christopherson@intel.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org Remove the code for handling stateful CPUID 0x2 and mark the associated flags as deprecated. WARN if host CPUID 0x2.0.AL > 1, i.e. if by some miracle a host with stateful CPUID 0x2 is encountered. No known CPU exists that supports hardware accelerated virtualization _and_ a stateful CPUID 0x2. Barring an extremely contrived nested virtualization scenario, stateful CPUID support is dead code. Suggested-by: Vitaly Kuznetsov Suggested-by: Paolo Bonzini Signed-off-by: Sean Christopherson --- Documentation/virt/kvm/api.rst | 22 ++-------- arch/x86/kvm/cpuid.c | 73 ++++++---------------------------- 2 files changed, 17 insertions(+), 78 deletions(-) diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst index ebd383fba939..c38cd9f88237 100644 --- a/Documentation/virt/kvm/api.rst +++ b/Documentation/virt/kvm/api.rst @@ -1574,8 +1574,8 @@ This ioctl would set vcpu's xcr to the value userspace specified. }; #define KVM_CPUID_FLAG_SIGNIFCANT_INDEX BIT(0) - #define KVM_CPUID_FLAG_STATEFUL_FUNC BIT(1) - #define KVM_CPUID_FLAG_STATE_READ_NEXT BIT(2) + #define KVM_CPUID_FLAG_STATEFUL_FUNC BIT(1) /* deprecated */ + #define KVM_CPUID_FLAG_STATE_READ_NEXT BIT(2) /* deprecated */ struct kvm_cpuid_entry2 { __u32 function; @@ -1626,13 +1626,6 @@ emulate them efficiently. The fields in each entry are defined as follows: KVM_CPUID_FLAG_SIGNIFCANT_INDEX: if the index field is valid - KVM_CPUID_FLAG_STATEFUL_FUNC: - if cpuid for this function returns different values for successive - invocations; there will be several entries with the same function, - all with this flag set - KVM_CPUID_FLAG_STATE_READ_NEXT: - for KVM_CPUID_FLAG_STATEFUL_FUNC entries, set if this entry is - the first entry to be read by a cpu eax, ebx, ecx, edx: the values returned by the cpuid instruction for @@ -3347,8 +3340,8 @@ The member 'flags' is used for passing flags from userspace. :: #define KVM_CPUID_FLAG_SIGNIFCANT_INDEX BIT(0) - #define KVM_CPUID_FLAG_STATEFUL_FUNC BIT(1) - #define KVM_CPUID_FLAG_STATE_READ_NEXT BIT(2) + #define KVM_CPUID_FLAG_STATEFUL_FUNC BIT(1) /* deprecated */ + #define KVM_CPUID_FLAG_STATE_READ_NEXT BIT(2) /* deprecated */ struct kvm_cpuid_entry2 { __u32 function; @@ -3394,13 +3387,6 @@ The fields in each entry are defined as follows: KVM_CPUID_FLAG_SIGNIFCANT_INDEX: if the index field is valid - KVM_CPUID_FLAG_STATEFUL_FUNC: - if cpuid for this function returns different values for successive - invocations; there will be several entries with the same function, - all with this flag set - KVM_CPUID_FLAG_STATE_READ_NEXT: - for KVM_CPUID_FLAG_STATEFUL_FUNC entries, set if this entry is - the first entry to be read by a cpu eax, ebx, ecx, edx: diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c index b5dce17c070f..49527dbcc90c 100644 --- a/arch/x86/kvm/cpuid.c +++ b/arch/x86/kvm/cpuid.c @@ -495,25 +495,16 @@ static inline int __do_cpuid_func(struct kvm_cpuid_array *array, u32 function) * time, with the least-significant byte in EAX enumerating the * number of times software should do CPUID(2, 0). * - * Modern CPUs (quite likely every CPU KVM has *ever* run on) - * are less idiotic. Intel's SDM states that EAX & 0xff "will - * always return 01H. Software should ignore this value and not + * Modern CPUs, i.e. every CPU KVM has *ever* run on are less + * idiotic. Intel's SDM states that EAX & 0xff "will always + * return 01H. Software should ignore this value and not * interpret it as an informational descriptor", while AMD's * APM states that CPUID(2) is reserved. + * + * WARN if a frankenstein CPU that supports virtualization and + * a stateful CPUID.0x2 is encountered. */ - max_idx = entry->eax & 0xff; - if (likely(max_idx <= 1)) - break; - - entry->flags |= KVM_CPUID_FLAG_STATEFUL_FUNC; - entry->flags |= KVM_CPUID_FLAG_STATE_READ_NEXT; - - for (i = 1; i < max_idx; ++i) { - entry = do_host_cpuid(array, function, 0); - if (!entry) - goto out; - entry->flags |= KVM_CPUID_FLAG_STATEFUL_FUNC; - } + WARN_ON_ONCE((entry->eax & 0xff) > 1); break; /* functions 4 and 0x8000001d have additional index. */ case 4: @@ -894,58 +885,20 @@ int kvm_dev_ioctl_get_cpuid(struct kvm_cpuid2 *cpuid, return r; } -static int move_to_next_stateful_cpuid_entry(struct kvm_vcpu *vcpu, int i) -{ - struct kvm_cpuid_entry2 *e = &vcpu->arch.cpuid_entries[i]; - struct kvm_cpuid_entry2 *ej; - int j = i; - int nent = vcpu->arch.cpuid_nent; - - e->flags &= ~KVM_CPUID_FLAG_STATE_READ_NEXT; - /* when no next entry is found, the current entry[i] is reselected */ - do { - j = (j + 1) % nent; - ej = &vcpu->arch.cpuid_entries[j]; - } while (ej->function != e->function); - - ej->flags |= KVM_CPUID_FLAG_STATE_READ_NEXT; - - return j; -} - -/* find an entry with matching function, matching index (if needed), and that - * should be read next (if it's stateful) */ -static int is_matching_cpuid_entry(struct kvm_cpuid_entry2 *e, - u32 function, u32 index) -{ - if (e->function != function) - return 0; - if ((e->flags & KVM_CPUID_FLAG_SIGNIFCANT_INDEX) && e->index != index) - return 0; - if (unlikely(e->flags & KVM_CPUID_FLAG_STATEFUL_FUNC) && - !(e->flags & KVM_CPUID_FLAG_STATE_READ_NEXT)) - return 0; - return 1; -} - struct kvm_cpuid_entry2 *kvm_find_cpuid_entry(struct kvm_vcpu *vcpu, u32 function, u32 index) { + struct kvm_cpuid_entry2 *e; int i; - struct kvm_cpuid_entry2 *best = NULL; for (i = 0; i < vcpu->arch.cpuid_nent; ++i) { - struct kvm_cpuid_entry2 *e; - e = &vcpu->arch.cpuid_entries[i]; - if (is_matching_cpuid_entry(e, function, index)) { - if (unlikely(e->flags & KVM_CPUID_FLAG_STATEFUL_FUNC)) - move_to_next_stateful_cpuid_entry(vcpu, i); - best = e; - break; - } + + if (e->function == function && (e->index == index || + !(e->flags & KVM_CPUID_FLAG_SIGNIFCANT_INDEX))) + return e; } - return best; + return NULL; } EXPORT_SYMBOL_GPL(kvm_find_cpuid_entry); -- 2.24.1