From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Hildenbrand Date: Mon, 25 Mar 2019 09:29:40 +0000 Subject: Re: [PATCH] kvm: vmx: Silence a shift wrap warning Message-Id: List-Id: References: <20190325090448.GB16023@kadam> In-Reply-To: <20190325090448.GB16023@kadam> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: kernel-janitors@vger.kernel.org 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 > --- > 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 > goto fail; > > switch (function) { > -- Thanks, David / dhildenb