KVM: move and fix substitue search for missing CPUID entries

[platform/kernel/linux-arm64.git] / arch / x86 / kvm / x86.c

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 4a1ba05..934b4c6 100644 (file)
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -4958,12 +4958,6 @@ struct kvm_cpuid_entry2 *kvm_find_cpuid_entry(struct kvm_vcpu *vcpu,
                        best = e;
                        break;
                }
-               /*
-                * Both basic or both extended?
-                */
-               if (((e->function ^ function) & 0x80000000) == 0)
-                       if (!best || e->function > best->function)
-                               best = e;
        }
        return best;
 }
@@ -4983,6 +4977,27 @@ not_found:
        return 36;
 }
 
+/*
+ * If no match is found, check whether we exceed the vCPU's limit
+ * and return the content of the highest valid _standard_ leaf instead.
+ * This is to satisfy the CPUID specification.
+ */
+static struct kvm_cpuid_entry2* check_cpuid_limit(struct kvm_vcpu *vcpu,
+                                                  u32 function, u32 index)
+{
+       struct kvm_cpuid_entry2 *maxlevel;
+
+       maxlevel = kvm_find_cpuid_entry(vcpu, function & 0x80000000, 0);
+       if (!maxlevel || maxlevel->eax >= function)
+               return NULL;
+       if (function & 0x80000000) {
+               maxlevel = kvm_find_cpuid_entry(vcpu, 0, 0);
+               if (!maxlevel)
+                       return NULL;
+       }
+       return kvm_find_cpuid_entry(vcpu, maxlevel->eax, index);
+}
+
 void kvm_emulate_cpuid(struct kvm_vcpu *vcpu)
 {
        u32 function, index;
@@ -4995,6 +5010,10 @@ void kvm_emulate_cpuid(struct kvm_vcpu *vcpu)
        kvm_register_write(vcpu, VCPU_REGS_RCX, 0);
        kvm_register_write(vcpu, VCPU_REGS_RDX, 0);
        best = kvm_find_cpuid_entry(vcpu, function, index);
+
+       if (!best)
+               best = check_cpuid_limit(vcpu, function, index);
+
        if (best) {
                kvm_register_write(vcpu, VCPU_REGS_RAX, best->eax);
                kvm_register_write(vcpu, VCPU_REGS_RBX, best->ebx);