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.
Yang explained to me (offlist) that this is needed because Windows fails
to reboot without it. We would need a way to ask Linux to reinitialize
the vEPC, that doesn't involve munmap/mmap; this could be for example
fallocate(FALLOC_FL_ZERO_RANGE).
What do you all think?
Paolo
