Re: [libvirt] [PATCH] qemu: Pass file descriptor when using TPM passthrough

From: Stefan Berger <stefanb(a)linux.vnet.ibm.com&gt; Pass the TPM file descriptor to QEMU via command line. Instead of passing /dev/tpm0 we now pass /dev/fdset/10 and the additional parameters -add-fd set=10,fd=20. This addresses the use case when QEMU is started with non-root privileges and QEMU cannot open /dev/tpm0 for example. One problem is that for the passing of the file descriptor set to work, virCommandReorderFDs must not be called on the virCommand. This is prevented by setting a flag in the virCommandPassFDGetFDIndex that is checked to be clear when virCommandReorderFDs is run.