Re: [PATCH] kvm: vmx: Silence a shift wrap warning

[David Hildenbrand <david@redhat.com>]

On 25.03.19 10:04, Dan Carpenter wrote:
> This code generates a Smatch warning:
> 
> arch/x86/kvm/vmx/nested.c:4828 handle_vmfunc() warn: should '(1 << function)' be a 64 bit type?
> 
> The warning is generated because "vmcs12->vm_function_control" is a u64
> but the shift can only test the lower 32 bits.  This doesn't cause a
> problem in the current code because we only use BIT(0).  This patch just
> silences the static checker warning.
> 
> Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
> ---
>  arch/x86/kvm/vmx/nested.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
> index f24a2c225070..1f4398246bd9 100644
> --- a/arch/x86/kvm/vmx/nested.c
> +++ b/arch/x86/kvm/vmx/nested.c
> @@ -4825,7 +4825,7 @@ static int handle_vmfunc(struct kvm_vcpu *vcpu)
>  	}
>  
>  	vmcs12 = get_vmcs12(vcpu);
> -	if ((vmcs12->vm_function_control & (1 << function)) = 0)
> +	if ((vmcs12->vm_function_control & (1ULL << function)) = 0)

I guess one set of parentheses could be dropped here, while touching the
line.

Reviewed-by: David Hildenbrand <david@redhat.com>

>  		goto fail;
>  
>  	switch (function) {
> 


-- 

Thanks,

David / dhildenb