Re: [patch] kvm: suppress KVM_SET_GSI_ROUTING allocation failure

[David Rientjes]

On Tue, 13 Feb 2018, Paolo Bonzini wrote:

> >> The KVM_SET_GSI_ROUTING ioctl does a vmalloc() of
> >> sizeof(struct kvm_irq_routing_entry) multiplied by a user-supplied value.
> >> This can be up to 4096 entries on architectures such as arm64 and s390
> >> (and the upper bound may be increased on s390 eventually).
> >>
> >> This can produce a vmalloc allocation failure warning:
> >>
> > [...]
> >>  kvm_vm_ioctl+0x910/0x15e0 arch/x86/kvm/../../../virt/kvm/kvm_main.c:4153
> > 
> >                                                                        ^^^^^
> > 
> >> @@ -3063,7 +3063,8 @@ static long kvm_vm_ioctl(struct file *filp,
> > 
> >       ^^^^^
> > 
> > 
> > Are you sure that you got the right vmalloc?
> 
> Nice catch!  But well, it's the only one in the whole file. :)
> 
> That seems very much like an old patch then.  I'm unqueuing it.
> 

It's not a catch at all, the fact that I saw this warning with an older 
kernel for KVM_SET_GSI_ROUTING doesn't mean that I can't patch it with an 
upstream kernel.  Would you prefer I remove the stack trace completely?