On Fri, 2021-09-10 at 17:10 +0200, Paolo Bonzini wrote:
> On 19/07/21 13:21, Yang Zhong wrote:
> > +void sgx_memory_backend_reset(HostMemoryBackend *backend, int fd,
> > + Error **errp)
> > +{
> > + MemoryRegion *mr = &backend->mr;
> > +
> > + mr->enabled = false;
> > +
> > + /* destroy the old memory region if it exist */
> > + if (fd > 0 && mr->destructor) {
> > + mr->destructor(mr);
> > + }
> > +
> > + sgx_epc_backend_memory_alloc(backend, errp);
> > +}
> > +
>
> Jarkko, Sean, Kai,
>
> this I think is problematic because it has a race window while
> /dev/sgx_vepc is closed and then reopened. First, the vEPC space could
> be exhausted by somebody doing another mmap in the meanwhile. Second,
> somebody might (for whatever reason) remove /dev/sgx_vepc while QEMU runs.
1: Why is it a problem that mmap() could fail?
2: Are you speaking about removing device node? If you have succesfully
mapped /dev/sgx_vepc, that should not have much effect (file refcount).
/Jarkko
