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Wanpeng Ligregkh
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KVM: LAPIC: Also cancel preemption timer during SET_LAPIC
commit 35fe7cf upstream. The below warning is splatting during guest reboot. ------------[ cut here ]------------ WARNING: CPU: 0 PID: 1931 at arch/x86/kvm/x86.c:10322 kvm_arch_vcpu_ioctl_run+0x874/0x880 [kvm] CPU: 0 PID: 1931 Comm: qemu-system-x86 Tainted: G I 5.17.0-rc1+ #5 RIP: 0010:kvm_arch_vcpu_ioctl_run+0x874/0x880 [kvm] Call Trace: <TASK> kvm_vcpu_ioctl+0x279/0x710 [kvm] __x64_sys_ioctl+0x83/0xb0 do_syscall_64+0x3b/0xc0 entry_SYSCALL_64_after_hwframe+0x44/0xae RIP: 0033:0x7fd39797350b This can be triggered by not exposing tsc-deadline mode and doing a reboot in the guest. The lapic_shutdown() function which is called in sys_reboot path will not disarm the flying timer, it just masks LVTT. lapic_shutdown() clears APIC state w/ LVT_MASKED and timer-mode bit is 0, this can trigger timer-mode switch between tsc-deadline and oneshot/periodic, which can result in preemption timer be cancelled in apic_update_lvtt(). However, We can't depend on this when not exposing tsc-deadline mode and oneshot/periodic modes emulated by preemption timer. Qemu will synchronise states around reset, let's cancel preemption timer under KVM_SET_LAPIC. Signed-off-by: Wanpeng Li <wanpengli@tencent.com> Message-Id: <1643102220-35667-1-git-send-email-wanpengli@tencent.com> Cc: stable@vger.kernel.org Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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arch/x86/kvm/lapic.c

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -2623,7 +2623,7 @@ int kvm_apic_set_state(struct kvm_vcpu *vcpu, struct kvm_lapic_state *s)
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kvm_apic_set_version(vcpu);
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apic_update_ppr(apic);
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hrtimer_cancel(&apic->lapic_timer.timer);
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cancel_apic_timer(apic);
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apic->lapic_timer.expired_tscdeadline = 0;
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apic_update_lvtt(apic);
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apic_manage_nmi_watchdog(apic, kvm_lapic_get_reg(apic, APIC_LVT0));

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