KVM: x86: Update number of entries for KVM_GET_CPUID2 on success, not failure
authorSean Christopherson <seanjc@google.com>
Fri, 26 May 2023 21:03:39 +0000 (14:03 -0700)
committerSean Christopherson <seanjc@google.com>
Thu, 1 Jun 2023 21:07:14 +0000 (14:07 -0700)
commitab322c43cce97ff6d05439c9b72bf1513e3e1020
tree8a024e2055877fa1e5900250bff12b3680cbd17f
parent0d42522bdee70b9197be63dd76c9f6297cd1e832
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 <itazur@amazon.com>
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 <seanjc@google.com>
arch/x86/kvm/cpuid.c