On Mon, May 25, 2020 at 06:00:08AM -0700, Tamas K Lengyel wrote: > When running shallow forks, ie. VM forks without device models (QEMU), it may > be undesirable for Xen to inject interrupts. When creating such forks from > Windows VMs we have observed the kernel trying to process interrupts > immediately after the fork is executed. However without QEMU running such > interrupt handling may not be possible because it may attempt to interact with > devices that are not emulated by a backend. In the best case scenario such > interrupt handling would only present a detour in the VM forks' execution > flow, but in the worst case as we actually observed can completely stall it. > By disabling interrupt injection a fuzzer can exercise the target code without > interference. For other use-cases this option probably doesn't make sense, > that's why this is not enabled by default. > > Forks & memory sharing are only available on Intel CPUs so this only applies > to vmx. Note that this is part of the experimental VM forking feature that's > completely disabled by default and can only be enabled by using > XEN_CONFIG_EXPERT during compile time. > > Signed-off-by: Tamas K Lengyel <tamas.leng...@intel.com>
Reviewed-by: Roger Pau Monné <roger....@citrix.com> Thanks, Roger.
