Re: [libvirt] [PATCH 3/3] qemu: Pass file descriptor when using TPM passthrough

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. Signed-off-by: Stefan Berger <stefanb(a)linux.vnet.ibm.com&gt; --- src/qemu/qemu_command.c | 121 ++++++++++++++++++++++++++++++++++++++++++++++-- 1 file changed, 117 insertions(+), 4 deletions(-) diff --git a/src/qemu/qemu_command.c b/src/qemu/qemu_command.c index 539c956..12e2e2f 100644 --- a/src/qemu/qemu_command.c +++ b/src/qemu/qemu_command.c @@ -161,6 +161,58 @@ VIR_ENUM_IMPL(qemuNumaPolicy, VIR_DOMAIN_NUMATUNE_MEM_LAST, "interleave"); /** + * qemuVirCommandGetFDSet: + * @cmd: the command to modify + * @fd: fd to reassign to the child + * + * Get the parameters for the QEMU -add-fd command line option + * for the given file descriptor. The file descriptor must previously + * have been 'transferred' in a virCommandPassFD() call. + * This function for example returns "set=10,fd=20". + */ +static char * +qemuVirCommandGetFDSet(virCommandPtr cmd, int fd) +{ + char *result = NULL; + int idx = virCommandPassFDGetFDIndex(cmd, fd); + + if (idx >= 0) { + ignore_value(virAsprintf(&result, "set=%d,fd=%d", idx, fd) < 0);