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 mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id A3258C433EF for ; Fri, 5 Nov 2021 09:51:36 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8A19361186 for ; Fri, 5 Nov 2021 09:51:36 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232910AbhKEJyN (ORCPT ); Fri, 5 Nov 2021 05:54:13 -0400 Received: from mail.xenproject.org ([104.130.215.37]:56594 "EHLO mail.xenproject.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232883AbhKEJyK (ORCPT ); Fri, 5 Nov 2021 05:54:10 -0400 Received: from xenbits.xenproject.org ([104.239.192.120]) by mail.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1mivsR-00048c-Jd; Fri, 05 Nov 2021 09:51:15 +0000 Received: from host86-165-42-146.range86-165.btcentralplus.com ([86.165.42.146] helo=debian.home) by xenbits.xenproject.org with esmtpsa (TLS1.3:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1mivsR-00088M-BO; Fri, 05 Nov 2021 09:51:15 +0000 From: Paul Durrant To: kvm@vger.kernel.org Cc: Paul Durrant , Paolo Bonzini , Sean Christopherson , Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Joerg Roedel Subject: [PATCH v2 2/2] KVM: x86: Make sure KVM_CPUID_FEATURES really are KVM_CPUID_FEATURES Date: Fri, 5 Nov 2021 09:51:01 +0000 Message-Id: <20211105095101.5384-3-pdurrant@amazon.com> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20211105095101.5384-1-pdurrant@amazon.com> References: <20211105095101.5384-1-pdurrant@amazon.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org Currently when kvm_update_cpuid_runtime() runs, it assumes that the KVM_CPUID_FEATURES leaf is located at 0x40000001. This is not true, however, if Hyper-V support is enabled. In this case the KVM leaves will be offset. This patch introdues as new 'kvm_cpuid_base' field into struct kvm_vcpu_arch to track the location of the KVM leaves and function kvm_update_kvm_cpuid_base() (called from kvm_set_cpuid()) to locate the leaves using the 'KVMKVMKVM\0\0\0' signature (which is now given a definition in kvm_para.h). Adjustment of KVM_CPUID_FEATURES will hence now target the correct leaf. NOTE: A new for_each_possible_hypervisor_cpuid_base() macro is intoduced into processor.h to avoid having duplicate code for the iteration over possible hypervisor base leaves. Signed-off-by: Paul Durrant --- Cc: Paolo Bonzini Cc: Sean Christopherson Cc: Vitaly Kuznetsov Cc: Wanpeng Li Cc: Jim Mattson Cc: Joerg Roedel v2: - Added new for_each_possible_hypervisor_cpuid_base() macro - Added KVM_SIGNATURE definition - Other amendments as requested by Sean --- arch/x86/include/asm/kvm_host.h | 1 + arch/x86/include/asm/processor.h | 5 ++- arch/x86/include/uapi/asm/kvm_para.h | 1 + arch/x86/kernel/kvm.c | 2 +- arch/x86/kvm/cpuid.c | 46 ++++++++++++++++++++++++---- 5 files changed, 47 insertions(+), 8 deletions(-) diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h index 88fce6ab4bbd..21133ffa23e9 100644 --- a/arch/x86/include/asm/kvm_host.h +++ b/arch/x86/include/asm/kvm_host.h @@ -725,6 +725,7 @@ struct kvm_vcpu_arch { int cpuid_nent; struct kvm_cpuid_entry2 *cpuid_entries; + u32 kvm_cpuid_base; u64 reserved_gpa_bits; int maxphyaddr; diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h index 9ad2acaaae9b..726318cda082 100644 --- a/arch/x86/include/asm/processor.h +++ b/arch/x86/include/asm/processor.h @@ -807,11 +807,14 @@ static inline u32 amd_get_nodes_per_socket(void) { return 0; } static inline u32 amd_get_highest_perf(void) { return 0; } #endif +#define for_each_possible_hypervisor_cpuid_base(function) \ + for (function = 0x40000000; function < 0x40010000; function += 0x100) + static inline uint32_t hypervisor_cpuid_base(const char *sig, uint32_t leaves) { uint32_t base, eax, signature[3]; - for (base = 0x40000000; base < 0x40010000; base += 0x100) { + for_each_possible_hypervisor_cpuid_base(base) { cpuid(base, &eax, &signature[0], &signature[1], &signature[2]); if (!memcmp(sig, signature, 12) && diff --git a/arch/x86/include/uapi/asm/kvm_para.h b/arch/x86/include/uapi/asm/kvm_para.h index 5146bbab84d4..6e64b27b2c1e 100644 --- a/arch/x86/include/uapi/asm/kvm_para.h +++ b/arch/x86/include/uapi/asm/kvm_para.h @@ -8,6 +8,7 @@ * should be used to determine that a VM is running under KVM. */ #define KVM_CPUID_SIGNATURE 0x40000000 +#define KVM_SIGNATURE "KVMKVMKVM\0\0\0" /* This CPUID returns two feature bitmaps in eax, edx. Before enabling * a particular paravirtualization, the appropriate feature bit should diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c index b656456c3a94..c97859170286 100644 --- a/arch/x86/kernel/kvm.c +++ b/arch/x86/kernel/kvm.c @@ -755,7 +755,7 @@ static noinline uint32_t __kvm_cpuid_base(void) return 0; /* So we don't blow up on old processors */ if (boot_cpu_has(X86_FEATURE_HYPERVISOR)) - return hypervisor_cpuid_base("KVMKVMKVM\0\0\0", 0); + return hypervisor_cpuid_base(KVM_SIGNATURE, 0); return 0; } diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c index 41529c168e91..e19dabf1848b 100644 --- a/arch/x86/kvm/cpuid.c +++ b/arch/x86/kvm/cpuid.c @@ -99,11 +99,45 @@ static int kvm_check_cpuid(struct kvm_cpuid_entry2 *entries, int nent) return 0; } -void kvm_update_pv_runtime(struct kvm_vcpu *vcpu) +static void kvm_update_kvm_cpuid_base(struct kvm_vcpu *vcpu) { - struct kvm_cpuid_entry2 *best; + u32 function; + struct kvm_cpuid_entry2 *entry; + + vcpu->arch.kvm_cpuid_base = 0; + + for_each_possible_hypervisor_cpuid_base(function) { + entry = kvm_find_cpuid_entry(vcpu, function, 0); + + if (entry) { + u32 signature[3]; + + signature[0] = entry->ebx; + signature[1] = entry->ecx; + signature[2] = entry->edx; + + BUILD_BUG_ON(sizeof(signature) > sizeof(KVM_SIGNATURE)); + if (!memcmp(signature, KVM_SIGNATURE, sizeof(signature))) { + vcpu->arch.kvm_cpuid_base = function; + break; + } + } + } +} + +struct kvm_cpuid_entry2 *kvm_find_kvm_cpuid_features(struct kvm_vcpu *vcpu) +{ + u32 base = vcpu->arch.kvm_cpuid_base; + + if (!base) + return NULL; + + return kvm_find_cpuid_entry(vcpu, base | KVM_CPUID_FEATURES, 0); +} - best = kvm_find_cpuid_entry(vcpu, KVM_CPUID_FEATURES, 0); +void kvm_update_pv_runtime(struct kvm_vcpu *vcpu) +{ + struct kvm_cpuid_entry2 *best = kvm_find_kvm_cpuid_features(vcpu); /* * save the feature bitmap to avoid cpuid lookup for every PV @@ -142,7 +176,7 @@ void kvm_update_cpuid_runtime(struct kvm_vcpu *vcpu) cpuid_entry_has(best, X86_FEATURE_XSAVEC))) best->ebx = xstate_required_size(vcpu->arch.xcr0, true); - best = kvm_find_cpuid_entry(vcpu, KVM_CPUID_FEATURES, 0); + best = kvm_find_kvm_cpuid_features(vcpu); if (kvm_hlt_in_guest(vcpu->kvm) && best && (best->eax & (1 << KVM_FEATURE_PV_UNHALT))) best->eax &= ~(1 << KVM_FEATURE_PV_UNHALT); @@ -252,6 +286,7 @@ static int kvm_set_cpuid(struct kvm_vcpu *vcpu, struct kvm_cpuid_entry2 *e2, vcpu->arch.cpuid_entries = e2; vcpu->arch.cpuid_nent = nent; + kvm_update_kvm_cpuid_base(vcpu); kvm_update_cpuid_runtime(vcpu); kvm_vcpu_after_set_cpuid(vcpu); @@ -872,8 +907,7 @@ static inline int __do_cpuid_func(struct kvm_cpuid_array *array, u32 function) } break; case KVM_CPUID_SIGNATURE: { - static const char signature[12] = "KVMKVMKVM\0\0"; - const u32 *sigptr = (const u32 *)signature; + const u32 *sigptr = (const u32 *)KVM_SIGNATURE; entry->eax = KVM_CPUID_FEATURES; entry->ebx = sigptr[0]; entry->ecx = sigptr[1]; -- 2.20.1