Re: [PATCH 2/2] KVM, Fix QEMU-KVM is killed by guest SRAO MCE

[Avi Kivity]

On 04/27/2010 12:25 PM, Huang Ying wrote:
> > On 04/27/2010 10:04 AM, Huang Ying wrote:
> >      
> > > +static void kvm_send_hwpoison_signal(struct kvm *kvm, gfn_t gfn)
> > > +{
> > > +	char buf[1];
> > > +	void __user *hva;
> > > +	int r;
> > > +
> > > +	/* Touch the page, so send SIGBUS */
> > > +	hva = (void __user *)gfn_to_hva(kvm, gfn);
> > > +	r = copy_from_user(buf, hva, 1);
> > >
> > >        
> > No error check?  What will a copy_from_user() of poisoned page expected
> > to return?
> >
> > Best to return -EFAULT on failure for consistency.
> >      
> Just want to use the side effect of copy_from_user, SIGBUS will be sent
> to current process because the page touched is marked as poisoned. That
> is, failure is expected, so the return value is not checked.
>    

What if the failure doesn't happen?  Say, someone mmap()ed over the page.

btw, better to use (void)copy_from_user(...) instead to avoid the 
initialized but not used warning the compiler may generate.


--
error compiling committee.c: too many arguments to function

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