On 25.05.2020 14:18, Tamas K Lengyel wrote: > On Mon, May 25, 2020 at 12:06 AM Jan Beulich <jbeul...@suse.com> wrote: >> >> On 22.05.2020 18:33, Tamas K Lengyel wrote: >>> When running shallow forks without device models it may be undesirable for >>> Xen >>> to inject interrupts. With Windows forks we have observed the kernel going >>> into >>> infinite loops when trying to process such interrupts, likely because it >>> attempts >>> to interact with devices that are not responding without QEMU running. By >>> disabling interrupt injection the fuzzer can exercise the target code >>> without >>> interference. >>> >>> Forks & memory sharing are only available on Intel CPUs so this only applies >>> to vmx. >> >> Looking at e.g. mem_sharing_control() I can't seem to be able to confirm >> this. Would you mind pointing me at where this restriction is coming from? > > Both mem_access and mem_sharing are only implemented for EPT: > http://xenbits.xen.org/hg/xen-unstable.hg/file/5eadf9363c25/xen/arch/x86/mm/p2m-ept.c#l126.
p2m-pt.c:p2m_type_to_flags() has a similar case label. And I can't spot a respective restriction in mem_sharing_memop(), i.e. it looks to me as if enabling mem-sharing on NPT (to satisfy hap_enabled() in mem_sharing_control()) would be possible. Jan
