[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: HVM guest only bring up a single vCPU
On Thu, Aug 26, 2021 at 10:00:58PM +0100, Julien Grall wrote: > Hi Andrew, > > While doing more testing today, I noticed that only one vCPU would be > brought up with HVM guest with Xen 4.16 on my setup (QEMU): > > [ 1.122180] > ================================================================================ > [ 1.122180] UBSAN: shift-out-of-bounds in > oss/linux/arch/x86/kernel/apic/apic.c:2362:13 > [ 1.122180] shift exponent -1 is negative > [ 1.122180] CPU: 0 PID: 1 Comm: swapper/0 Not tainted 5.14.0-rc7+ #304 > [ 1.122180] Hardware name: Xen HVM domU, BIOS 4.16-unstable 06/07/2021 > [ 1.122180] Call Trace: > [ 1.122180] dump_stack_lvl+0x56/0x6c > [ 1.122180] ubsan_epilogue+0x5/0x50 > [ 1.122180] __ubsan_handle_shift_out_of_bounds+0xfa/0x140 > [ 1.122180] ? cgroup_kill_write+0x4d/0x150 > [ 1.122180] ? cpu_up+0x6e/0x100 > [ 1.122180] ? _raw_spin_unlock_irqrestore+0x30/0x50 > [ 1.122180] ? rcu_read_lock_held_common+0xe/0x40 > [ 1.122180] ? irq_shutdown_and_deactivate+0x11/0x30 > [ 1.122180] ? lock_release+0xc7/0x2a0 > [ 1.122180] ? apic_id_is_primary_thread+0x56/0x60 > [ 1.122180] apic_id_is_primary_thread+0x56/0x60 > [ 1.122180] cpu_up+0xbd/0x100 > [ 1.122180] bringup_nonboot_cpus+0x4f/0x60 > [ 1.122180] smp_init+0x26/0x74 > [ 1.122180] kernel_init_freeable+0x183/0x32d > [ 1.122180] ? _raw_spin_unlock_irq+0x24/0x40 > [ 1.122180] ? rest_init+0x330/0x330 > [ 1.122180] kernel_init+0x17/0x140 > [ 1.122180] ? rest_init+0x330/0x330 > [ 1.122180] ret_from_fork+0x22/0x30 > [ 1.122244] > ================================================================================ > [ 1.123176] installing Xen timer for CPU 1 > [ 1.123369] x86: Booting SMP configuration: > [ 1.123409] .... node #0, CPUs: #1 > [ 1.154400] Callback from call_rcu_tasks_trace() invoked. > [ 1.154491] smp: Brought up 1 node, 1 CPU > [ 1.154526] smpboot: Max logical packages: 2 > [ 1.154570] smpboot: Total of 1 processors activated (5999.99 BogoMIPS) > > I have tried a PV guest (same setup) and the kernel could bring up all the > vCPUs. > > Digging down, Linux will set smp_num_siblings to 0 (via detect_ht_early()) > and as a result will skip all the CPUs. The value is retrieve from a CPUID > leaf. So it sounds like we don't set the leaft correctly. > > FWIW, I have also tried on Xen 4.11 and could spot the same issue. Does this > ring any bell to you? Is it maybe this: https://lore.kernel.org/xen-devel/20201106003529.391649-1-bmasney@xxxxxxxxxx/T/#u ? -- Best Regards, Marek Marczykowski-Górecki Invisible Things Lab Attachment:
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