From: Wanpeng Li <[email protected]>
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 <[email protected]>
---
arch/x86/kvm/lapic.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
index baca9fa37a91..4662469240bc 100644
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -2629,7 +2629,7 @@ int kvm_apic_set_state(struct kvm_vcpu *vcpu, struct kvm_lapic_state *s)
kvm_apic_set_version(vcpu);
apic_update_ppr(apic);
- hrtimer_cancel(&apic->lapic_timer.timer);
+ cancel_apic_timer(apic);
apic->lapic_timer.expired_tscdeadline = 0;
apic_update_lvtt(apic);
apic_manage_nmi_watchdog(apic, kvm_lapic_get_reg(apic, APIC_LVT0));
--
2.25.1
On 1/25/22 10:17, Wanpeng Li wrote:
> From: Wanpeng Li <[email protected]>
>
> 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 <[email protected]>
> ---
> arch/x86/kvm/lapic.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
> index baca9fa37a91..4662469240bc 100644
> --- a/arch/x86/kvm/lapic.c
> +++ b/arch/x86/kvm/lapic.c
> @@ -2629,7 +2629,7 @@ int kvm_apic_set_state(struct kvm_vcpu *vcpu, struct kvm_lapic_state *s)
> kvm_apic_set_version(vcpu);
>
> apic_update_ppr(apic);
> - hrtimer_cancel(&apic->lapic_timer.timer);
> + cancel_apic_timer(apic);
> apic->lapic_timer.expired_tscdeadline = 0;
> apic_update_lvtt(apic);
> apic_manage_nmi_watchdog(apic, kvm_lapic_get_reg(apic, APIC_LVT0));
Queued, with Cc to stable.
Paolo