diff options
Diffstat (limited to 'arch/x86/kvm/cpuid.c')
| -rw-r--r-- | arch/x86/kvm/cpuid.c | 45 |
1 files changed, 39 insertions, 6 deletions
diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c index ec91b9b127fa..299ed439af25 100644 --- a/arch/x86/kvm/cpuid.c +++ b/arch/x86/kvm/cpuid.c @@ -918,16 +918,49 @@ struct kvm_cpuid_entry2 *kvm_find_cpuid_entry(struct kvm_vcpu *vcpu, EXPORT_SYMBOL_GPL(kvm_find_cpuid_entry); /* - * If the basic or extended CPUID leaf requested is higher than the - * maximum supported basic or extended leaf, respectively, then it is - * out of range. + * Intel CPUID semantics treats any query for an out-of-range leaf as if the + * highest basic leaf (i.e. CPUID.0H:EAX) were requested. AMD CPUID semantics + * returns all zeroes for any undefined leaf, whether or not the leaf is in + * range. Centaur/VIA follows Intel semantics. + * + * A leaf is considered out-of-range if its function is higher than the maximum + * supported leaf of its associated class or if its associated class does not + * exist. + * + * There are three primary classes to be considered, with their respective + * ranges described as "<base> - <top>[,<base2> - <top2>] inclusive. A primary + * class exists if a guest CPUID entry for its <base> leaf exists. For a given + * class, CPUID.<base>.EAX contains the max supported leaf for the class. + * + * - Basic: 0x00000000 - 0x3fffffff, 0x50000000 - 0x7fffffff + * - Hypervisor: 0x40000000 - 0x4fffffff + * - Extended: 0x80000000 - 0xbfffffff + * - Centaur: 0xc0000000 - 0xcfffffff + * + * The Hypervisor class is further subdivided into sub-classes that each act as + * their own indepdent class associated with a 0x100 byte range. E.g. if Qemu + * is advertising support for both HyperV and KVM, the resulting Hypervisor + * CPUID sub-classes are: + * + * - HyperV: 0x40000000 - 0x400000ff + * - KVM: 0x40000100 - 0x400001ff */ static bool cpuid_function_in_range(struct kvm_vcpu *vcpu, u32 function) { - struct kvm_cpuid_entry2 *max; + struct kvm_cpuid_entry2 *basic, *class; + + basic = kvm_find_cpuid_entry(vcpu, 0, 0); + if (!basic) + return true; + + if (function >= 0x40000000 && function <= 0x4fffffff) + class = kvm_find_cpuid_entry(vcpu, function & 0xffffff00, 0); + else if (function >= 0xc0000000) + class = kvm_find_cpuid_entry(vcpu, 0xc0000000, 0); + else + class = kvm_find_cpuid_entry(vcpu, function & 0x80000000, 0); - max = kvm_find_cpuid_entry(vcpu, function & 0x80000000, 0); - return max && function <= max->eax; + return class && function <= class->eax; } bool kvm_cpuid(struct kvm_vcpu *vcpu, u32 *eax, u32 *ebx, |