On 06/09/2021 09:23, Juergen Gross wrote: > On 03.09.21 17:41, Bertrand Marquis wrote: >> Hi, >> >> While doing some investigation with cpupools I encountered a crash >> when trying to isolate a guest to its own physical cpu. >> >> I am using current staging status. >> >> I did the following (on FVP with 8 cores): >> - start dom0 with dom0_max_vcpus=1 >> - remove core 1 from dom0 cpupool: xl cpupool-cpu-remove Pool-0 1 >> - create a new pool: xl cpupool-create name=\"NetPool\” >> - add core 1 to the pool: xl cpupool-cpu-add NetPool 1 >> - create a guest in NetPool using the following in the guest config: >> pool=“NetPool" >> >> I end with a crash with the following call trace during guest creation: >> (XEN) Xen call trace: >> (XEN) [<0000000000234cb0>] credit2.c#csched2_alloc_udata+0x58/0xfc >> (PC) >> (XEN) [<0000000000234c80>] credit2.c#csched2_alloc_udata+0x28/0xfc >> (LR) >> (XEN) [<0000000000242d38>] sched_move_domain+0x144/0x6c0 >> (XEN) [<000000000022dd18>] >> cpupool.c#cpupool_move_domain_locked+0x38/0x70 >> (XEN) [<000000000022fadc>] cpupool_do_sysctl+0x73c/0x780 >> (XEN) [<000000000022d8e0>] do_sysctl+0x788/0xa58 >> (XEN) [<0000000000273b68>] traps.c#do_trap_hypercall+0x78/0x170 >> (XEN) [<0000000000274f70>] do_trap_guest_sync+0x138/0x618 >> (XEN) [<0000000000260458>] entry.o#guest_sync_slowpath+0xa4/0xd4 >> >> After some debugging I found out that unit->vcpu_list is NULL after >> unit->vcpu_list = d->vcpu[unit->unit_id]; with unit_id 0 in >> common/sched/core.c:688 >> This makes the call to is_idle_unit(unit) in csched2_alloc_udata >> trigger the crash. > > So there is no vcpu 0 in that domain? How is this possible?
Easy, depending on the order of hypercalls issued by the toolstack. Between DOMCTL_createdomain and DOMCTL_max_vcpus, the domain exists but the vcpus haven't been allocated. ~Andrew
