From: Alexey Kardashevskiy Date: Fri, 29 Mar 2019 05:40:13 +0000 (+1100) Subject: KVM: PPC: Book3S HV: Fix lockdep warning when entering the guest X-Git-Url: http://git.lede-project.org./?a=commitdiff_plain;h=3309bec85e60;p=openwrt%2Fstaging%2Fblogic.git KVM: PPC: Book3S HV: Fix lockdep warning when entering the guest The trace_hardirqs_on() sets current->hardirqs_enabled and from here the lockdep assumes interrupts are enabled although they are remain disabled until the context switches to the guest. Consequent srcu_read_lock() checks the flags in rcu_lock_acquire(), observes disabled interrupts and prints a warning (see below). This moves trace_hardirqs_on/off closer to __kvmppc_vcore_entry to prevent lockdep from being confused. DEBUG_LOCKS_WARN_ON(current->hardirqs_enabled) WARNING: CPU: 16 PID: 8038 at kernel/locking/lockdep.c:4128 check_flags.part.25+0x224/0x280 [...] NIP [c000000000185b84] check_flags.part.25+0x224/0x280 LR [c000000000185b80] check_flags.part.25+0x220/0x280 Call Trace: [c000003fec253710] [c000000000185b80] check_flags.part.25+0x220/0x280 (unreliable) [c000003fec253780] [c000000000187ea4] lock_acquire+0x94/0x260 [c000003fec253840] [c00800001a1e9768] kvmppc_run_core+0xa60/0x1ab0 [kvm_hv] [c000003fec253a10] [c00800001a1ed944] kvmppc_vcpu_run_hv+0x73c/0xec0 [kvm_hv] [c000003fec253ae0] [c00800001a1095dc] kvmppc_vcpu_run+0x34/0x48 [kvm] [c000003fec253b00] [c00800001a1056bc] kvm_arch_vcpu_ioctl_run+0x2f4/0x400 [kvm] [c000003fec253b90] [c00800001a0f3618] kvm_vcpu_ioctl+0x460/0x850 [kvm] [c000003fec253d00] [c00000000041c4f4] do_vfs_ioctl+0xe4/0x930 [c000003fec253db0] [c00000000041ce04] ksys_ioctl+0xc4/0x110 [c000003fec253e00] [c00000000041ce78] sys_ioctl+0x28/0x80 [c000003fec253e20] [c00000000000b5a4] system_call+0x5c/0x70 Instruction dump: 419e0034 3d220004 39291730 81290000 2f890000 409e0020 3c82ffc6 3c62ffc5 3884be70 386329c0 4bf6ea71 60000000 <0fe00000> 3c62ffc6 3863be90 4801273d irq event stamp: 1025 hardirqs last enabled at (1025): [] kvmppc_run_core+0xa20/0x1ab0 [kvm_hv] hardirqs last disabled at (1024): [] kvmppc_run_core+0x650/0x1ab0 [kvm_hv] softirqs last enabled at (0): [] copy_process.isra.4.part.5+0x5f0/0x1d00 softirqs last disabled at (0): [<0000000000000000>] (null) ---[ end trace 31180adcc848993e ]--- possible reason: unannotated irqs-off. irq event stamp: 1025 hardirqs last enabled at (1025): [] kvmppc_run_core+0xa20/0x1ab0 [kvm_hv] hardirqs last disabled at (1024): [] kvmppc_run_core+0x650/0x1ab0 [kvm_hv] softirqs last enabled at (0): [] copy_process.isra.4.part.5+0x5f0/0x1d00 softirqs last disabled at (0): [<0000000000000000>] (null) Fixes: 8b24e69fc47e ("KVM: PPC: Book3S HV: Close race with testing for signals on guest entry", 2017-06-26) Signed-off-by: Alexey Kardashevskiy Signed-off-by: Paul Mackerras --- diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c index 6a519b590474..696fc569ba65 100644 --- a/arch/powerpc/kvm/book3s_hv.c +++ b/arch/powerpc/kvm/book3s_hv.c @@ -3322,25 +3322,26 @@ static noinline void kvmppc_run_core(struct kvmppc_vcore *vc) kvmppc_radix_check_need_tlb_flush(vc->kvm, pcpu, NULL); } - /* - * Interrupts will be enabled once we get into the guest, - * so tell lockdep that we're about to enable interrupts. - */ - trace_hardirqs_on(); - guest_enter_irqoff(); srcu_idx = srcu_read_lock(&vc->kvm->srcu); this_cpu_disable_ftrace(); + /* + * Interrupts will be enabled once we get into the guest, + * so tell lockdep that we're about to enable interrupts. + */ + trace_hardirqs_on(); + trap = __kvmppc_vcore_entry(); + trace_hardirqs_off(); + this_cpu_enable_ftrace(); srcu_read_unlock(&vc->kvm->srcu, srcu_idx); - trace_hardirqs_off(); set_irq_happened(trap); spin_lock(&vc->lock);