KVM: Add and use pr_unimpl for standard formatting of unimplemented features

All guest-invokable printks should be ratelimited to prevent malicious
guests from flooding logs.  This is a start.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Avi Kivity <avi@qumranet.com>

1 files changed, 8 insertions, 0 deletions

diff --git a/drivers/kvm/kvm.h b/drivers/kvm/kvm.h
index cfda3abff89a..6d258261891e 100644
--- a/drivers/kvm/kvm.h
+++ b/drivers/kvm/kvm.h
@@ -474,6 +474,14 @@ struct kvm_arch_ops {
 
 extern struct kvm_arch_ops *kvm_arch_ops;
 
+/* The guest did something we don't support. */
+#define pr_unimpl(vcpu, fmt, ...)                                       \
+ do {                                                                   \
+        if (printk_ratelimit())                                         \
+                printk(KERN_ERR "kvm: %i: cpu%i " fmt,                  \
+                       current->tgid, (vcpu)->vcpu_id , ## __VA_ARGS__); \
+ } while(0)
+
 #define kvm_printf(kvm, fmt ...) printk(KERN_DEBUG fmt)
 #define vcpu_printf(vcpu, fmt...) kvm_printf(vcpu->kvm, fmt)