From ab322c43cce97ff6d05439c9b72bf1513e3e1020 Mon Sep 17 00:00:00 2001 From: Sean Christopherson Date: Fri, 26 May 2023 14:03:39 -0700 Subject: KVM: x86: Update number of entries for KVM_GET_CPUID2 on success, not failure Update cpuid->nent if and only if kvm_vcpu_ioctl_get_cpuid2() succeeds. The sole caller copies @cpuid to userspace only on success, i.e. the existing code effectively does nothing. Arguably, KVM should report the number of entries when returning -E2BIG so that userspace doesn't have to guess the size, but all other similar KVM ioctls() don't report the size either, i.e. userspace is conditioned to guess. Suggested-by: Takahiro Itazuri Link: https://lore.kernel.org/all/20230410141820.57328-1-itazur@amazon.com Link: https://lore.kernel.org/r/20230526210340.2799158-2-seanjc@google.com Signed-off-by: Sean Christopherson --- arch/x86/kvm/cpuid.c | 13 ++++--------- 1 file changed, 4 insertions(+), 9 deletions(-) (limited to 'arch/x86/kvm/cpuid.c') diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c index 0c9660a07b23..241f554f1764 100644 --- a/arch/x86/kvm/cpuid.c +++ b/arch/x86/kvm/cpuid.c @@ -501,20 +501,15 @@ int kvm_vcpu_ioctl_get_cpuid2(struct kvm_vcpu *vcpu, struct kvm_cpuid2 *cpuid, struct kvm_cpuid_entry2 __user *entries) { - int r; - - r = -E2BIG; if (cpuid->nent < vcpu->arch.cpuid_nent) - goto out; - r = -EFAULT; + return -E2BIG; + if (copy_to_user(entries, vcpu->arch.cpuid_entries, vcpu->arch.cpuid_nent * sizeof(struct kvm_cpuid_entry2))) - goto out; - return 0; + return -EFAULT; -out: cpuid->nent = vcpu->arch.cpuid_nent; - return r; + return 0; } /* Mask kvm_cpu_caps for @leaf with the raw CPUID capabilities of this CPU. */ -- cgit v1.2.3