KVM: x86: fix CPUID entries returned by KVM_GET_CPUID2 ioctl

KVM: x86: fix CPUID entries returned by KVM_GET_CPUID2 ioctl

Recent commit 255cbecfe0 modified struct kvm_vcpu_arch to make
'cpuid_entries' a pointer to an array of kvm_cpuid_entry2 entries
rather than embedding the array in the struct. KVM_SET_CPUID and
KVM_SET_CPUID2 were updated accordingly, but KVM_GET_CPUID2 was missed.

As a result, KVM_GET_CPUID2 currently returns random fields from struct
kvm_vcpu_arch to userspace rather than the expected CPUID values. Fix
this by treating 'cpuid_entries' as a pointer when copying its
contents to userspace buffer.

Fixes: 255cbecfe0c9 ("KVM: x86: allocate vcpu->arch.cpuid_entries dynamically")
Cc: Vitaly Kuznetsov <[email protected]>
Signed-off-by: Michael Roth <[email protected]>
Message-Id: <20210128024451.1816770[email protected]>
Cc: [email protected]
Signed-off-by: Paolo Bonzini <[email protected]>