KVM: arm64: Don't initialize idreg debugfs w/ preemption disabled
Testing KVM with DEBUG_ATOMIC_SLEEP enabled doesn't get far before hitting the
first splat:
BUG: sleeping function called from invalid context at kernel/locking/rwsem.c:1578
in_atomic(): 1, irqs_disabled(): 0, non_block: 0, pid: 13062, name: vgic_lpi_stress
preempt_count: 1, expected: 0
2 locks held by vgic_lpi_stress/13062:
#0: ffff080084553240 (&vcpu->mutex){+.+.}-{3:3}, at: kvm_vcpu_ioctl+0xc0/0x13f0
#1: ffff800080485f08 (&kvm->arch.config_lock){+.+.}-{3:3}, at: kvm_arch_vcpu_ioctl+0xd60/0x1788
CPU: 19 PID: 13062 Comm: vgic_lpi_stress Tainted: G W O 6.8.0-dbg-DEV #1
Call trace:
dump_backtrace+0xf8/0x148
show_stack+0x20/0x38
dump_stack_lvl+0xb4/0xf8
dump_stack+0x18/0x40
__might_resched+0x248/0x2a0
__might_sleep+0x50/0x88
down_write+0x30/0x150
start_creating+0x90/0x1a0
__debugfs_create_file+0x5c/0x1b0
debugfs_create_file+0x34/0x48
kvm_reset_sys_regs+0x120/0x1e8
kvm_reset_vcpu+0x148/0x270
kvm_arch_vcpu_ioctl+0xddc/0x1788
kvm_vcpu_ioctl+0xb6c/0x13f0
__arm64_sys_ioctl+0x98/0xd8
invoke_syscall+0x48/0x108
el0_svc_common+0xb4/0xf0
do_el0_svc+0x24/0x38
el0_svc+0x54/0x128
el0t_64_sync_handler+0x68/0xc0
el0t_64_sync+0x1a8/0x1b0
kvm_reset_vcpu() disables preemption as it needs to unload vCPU state
from the CPU to twiddle with it, which subsequently explodes when
taking the parent inode's rwsem while creating the idreg debugfs file.
Fix it by moving the initialization to kvm_arch_create_vm_debugfs().
Fixes: 891766581dea ("KVM: arm64: Add debugfs file for guest's ID registers")
Reviewed-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20240227094115.1723330-3-oliver.upton@linux.dev
Signed-off-by: Oliver Upton <oliver.upton@linux.dev>
3 files changed
