On Thu, Mar 02, 2023, Wang, Wei W wrote:
> On Thursday, March 2, 2023 3:47 AM, David Matlack wrote:
> > On Wed, Mar 1, 2023 at 5:38 AM Wei Wang <wei.w.wang@xxxxxxxxx> wrote:
> > >
> > > Current KVM_BUG and KVM_BUG_ON assumes that 'cond' passed from
> > callers
> > > is 32-bit as it casts 'cond' to the type of int. This will be wrong if 'cond'
> > > provided by a caller is 64-bit, e.g. an error code of
> > > 0xc0000d0300000000 will be converted to 0, which is not expected.
> > > Improves the implementation by using !!(cond) in KVM_BUG and
> > > KVM_BUG_ON. Compared to changing 'int' to 'int64_t', this has less LOCs.
> >
> > Less LOC is nice to have, but please preserve the behavior that "cond"
> > is evaluated only once by KVM_BUG() and KVM_BUG_ON(). i.e.
> > KVM_BUG_ON(do_something(), kvm) should only result in a single call to
> > do_something().
>
> Good point, thanks! Using 'typeof(cond)' looks like a better choice.
I don't get it. Why bothering the type if we just do this?
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index 4f26b244f6d0..10455253c6ea 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -848,7 +848,7 @@ static inline void kvm_vm_bugged(struct kvm *kvm)
#define KVM_BUG(cond, kvm, fmt...) \
({ \
- int __ret = (cond); \
+ int __ret = !!(cond); \
\
if (WARN_ONCE(__ret && !(kvm)->vm_bugged, fmt)) \
kvm_vm_bugged(kvm); \
@@ -857,7 +857,7 @@ static inline void kvm_vm_bugged(struct kvm *kvm)
#define KVM_BUG_ON(cond, kvm) \
({ \
- int __ret = (cond); \
+ int __ret = !!(cond); \
\
if (WARN_ON_ONCE(__ret && !(kvm)->vm_bugged)) \
kvm_vm_bugged(kvm); \
