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().
>
> Fixes: 0b8f11737cff ("KVM: Add infrastructure and macro to mark VM as bugged")
> Signed-off-by: Wei Wang <wei.w.wang@xxxxxxxxx>
> ---
> include/linux/kvm_host.h | 12 ++++--------
> 1 file changed, 4 insertions(+), 8 deletions(-)
>
> diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
> index f06635b24bd0..d77ddf82c5c8 100644
> --- a/include/linux/kvm_host.h
> +++ b/include/linux/kvm_host.h
> @@ -881,20 +881,16 @@ static inline void kvm_vm_bugged(struct kvm *kvm)
>
> #define KVM_BUG(cond, kvm, fmt...) \
> ({ \
> - int __ret = (cond); \
> - \
> - if (WARN_ONCE(__ret && !(kvm)->vm_bugged, fmt)) \
> + if (WARN_ONCE(!!cond && !(kvm)->vm_bugged, fmt)) \
> kvm_vm_bugged(kvm); \
> - unlikely(__ret); \
> + unlikely(!!cond); \
> })
>
> #define KVM_BUG_ON(cond, kvm) \
> ({ \
> - int __ret = (cond); \
> - \
> - if (WARN_ON_ONCE(__ret && !(kvm)->vm_bugged)) \
> + if (WARN_ON_ONCE(!!(cond) && !(kvm)->vm_bugged)) \
> kvm_vm_bugged(kvm); \
> - unlikely(__ret); \
> + unlikely(!!(cond)); \
> })
