Re: [PATCH] KVM: apic: avoid calculating pending eoi from an uninitialized val

[linmiaohe]

Sean Christopherson <sean.j.christopherson@xxxxxxxxx> wrote:
>On Thu, Feb 20, 2020 at 05:33:17PM +0100, Vitaly Kuznetsov wrote:
>> linmiaohe <linmiaohe@xxxxxxxxxx> writes:
>> 
>
>Rather than initialize @val, I'd prefer to explicitly handle the error, similar to pv_eoi_clr_pending() and pv_eoi_set_pending(), e.g.
>
>	u8 val;
>
>	if (pv_eoi_get_user(vcpu, &val) < 0) {
>		printk(KERN_WARNING "Can't read EOI MSR value: 0x%llx\n",
>			   (unsigned long long)vcpu->arch.pv_eoi.msr_val);
>		return false;
>	}
>	return val & 0x1;

Looks good. Handle the error explicitly can help remind us @val is unusable.
Will do. Thanks.

>> >  	if (pv_eoi_get_user(vcpu, &val) < 0)
>> >  		printk(KERN_WARNING "Can't read EOI MSR value: 0x%llx\n",
>> >  			   (unsigned long long)vcpu->arch.pv_eoi.msr_val);
>> 
>> Reviewed-by: Vitaly Kuznetsov <vkuznets@xxxxxxxxxx>
>> 
>> But why compilers don't complain?
>
>Clang might?
>