Hi all,
enabling lockdep I see the following reported in the host when I start a kvm guest:
[12399.954245] CPU0 CPU1
[12399.958762] ---- ----
[12399.963279] lock(&(&dist->lpi_list_lock)->rlock);
[12399.968146] local_irq_disable();
[12399.974052] lock(&(&vgic_cpu->ap_list_lock)->rlock);
[12399.981696] lock(&(&dist->lpi_list_lock)->rlock);
[12399.989081] <Interrupt>
[12399.991688] lock(&(&vgic_cpu->ap_list_lock)->rlock);
[12399.996989]
*** DEADLOCK ***
[12400.002897] 2 locks held by qemu-system-aar/5597:
[12400.007587] #0: 0000000042beb9dc (&vcpu->mutex){+.+.}, at: kvm_vcpu_ioctl+0x7c/0xa68
[12400.015411] #1: 00000000c45d644a (&(&vgic_cpu->ap_list_lock)->rlock){-.-.}, at: kvm_vgic_sync_hwstate+0x8c/0x328
There is nothing unusual in my config or qemu parameters, I can upload these
if needed. I see this on ThunderX and ThunderX2 and also with older kernels
(4.13+ distribution kernel).
I tried making the lpi_list_lock irq safe but that just leads to different
warnings. The locking here seems to be quite sophisticated and I'm not familiar
with it.
Full dmesg: https://paste.ubuntu.com/p/BZ5QTg62Ym/
--Jan
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