Modify the KVM_GET_CPUID2 API to return the number of valid entries in nent field of kvm_cpuid2, even when the API is successful. Previously, the KVM_GET_CPUID2 API only updated the nent field when an error was returned. If the API was called with an entry count larger than necessary (e.g., KVM_MAX_CPUID_ENTRIES), it would succeed, but the nent field would continue to show a value larger than the actual number of entries filled by the KVM_GET_CPUID2 API. With this change, users can rely on the updated nent field and there is no need to traverse unnecessary entries and check whether an entry is valid or not. Signed-off-by: Takahiro Itazuri <itazur@xxxxxxxxxx> --- arch/x86/kvm/cpuid.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c index 599aebec2d52..31838dfddda6 100644 --- a/arch/x86/kvm/cpuid.c +++ b/arch/x86/kvm/cpuid.c @@ -523,10 +523,13 @@ int kvm_vcpu_ioctl_get_cpuid2(struct kvm_vcpu *vcpu, struct kvm_cpuid2 *cpuid, struct kvm_cpuid_entry2 __user *entries) { - int r; + int nent, r; + + nent = cpuid->nent; + cpuid->nent = vcpu->arch.cpuid_nent; r = -E2BIG; - if (cpuid->nent < vcpu->arch.cpuid_nent) + if (nent < vcpu->arch.cpuid_nent) goto out; r = -EFAULT; if (copy_to_user(entries, vcpu->arch.cpuid_entries, @@ -535,7 +538,6 @@ int kvm_vcpu_ioctl_get_cpuid2(struct kvm_vcpu *vcpu, return 0; out: - cpuid->nent = vcpu->arch.cpuid_nent; return r; } -- 2.39.2