KVM: fix cpuid E2BIG handling for extended request types

(cherry picked from commit cb007648)

If we run out of cpuid entries for extended request types
we should return -E2BIG, just like we do for the standard
request types.
Signed-off-by: Mark McLoughlin <markmc@redhat.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

arch/x86/kvm/x86.c

@@ -1448,6 +1448,10 @@ static int kvm_dev_ioctl_get_supported_cpuid(struct kvm_cpuid2 *cpuid,
 	for (func = 0x80000001; func <= limit && nent < cpuid->nent; ++func)
 		do_cpuid_ent(&cpuid_entries[nent], func, 0,
 			     &nent, cpuid->nent);
+	r = -E2BIG;
+	if (nent >= cpuid->nent)
+		goto out_free;
+
 	r = -EFAULT;
 	if (copy_to_user(entries, cpuid_entries,
 			 nent * sizeof(struct kvm_cpuid_entry2)))