HI Juergen, > On 6 Sep 2021, at 10:28, Juergen Gross <jgr...@suse.com> wrote: > > On 06.09.21 10:46, Andrew Cooper wrote: >> 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. > > Oh yes, indeed. > > Bertrand, does the attached patch fix the issue for you?
It does, my guest is now booting properly :-) So this is solving the issue on arm (and probably on x86 if it was present but untested by me). Feel free to add to your patch my: Reviewed-by: Bertrand Marquis <bertrand.marq...@arm.com> Thanks a lot for the quick fix Cheers Bertrand > > > Juergen > <0001-xen-sched-fix-sched_move_domain-for-domain-without-v.patch><OpenPGP_0xB0DE9DD628BF132F.asc>
