• Wanpeng Li's avatar
    KVM: lapic: fix access preemption timer stuff even if kernel_irqchip=off · 91005300
    Wanpeng Li authored
    BUG: unable to handle kernel NULL pointer dereference at 000000000000008c
    IP: [<ffffffffc04e0180>] kvm_lapic_hv_timer_in_use+0x10/0x20 [kvm]
    PGD 0
    Oops: 0000 [#1] SMP
    Call Trace:
     kvm_arch_vcpu_load+0x86/0x260 [kvm]
     vcpu_load+0x46/0x60 [kvm]
     kvm_vcpu_ioctl+0x79/0x7c0 [kvm]
     ? __lock_is_held+0x54/0x70
     do_vfs_ioctl+0x96/0x6a0
     ? __fget_light+0x2a/0x90
     SyS_ioctl+0x79/0x90
     do_syscall_64+0x7c/0x1e0
     entry_SYSCALL64_slow_path+0x25/0x25
    RIP  [<ffffffffc04e0180>] kvm_lapic_hv_timer_in_use+0x10/0x20 [kvm]
     RSP <ffff8800db1f3d70>
    CR2: 000000000000008c
    ---[ end trace a55fb79d2b3b4ee8 ]---
    
    This can be reproduced steadily by kernel_irqchip=off.
    
    We should not access preemption timer stuff if lapic is emulated in userspace.
    This patch fix it by avoiding access preemption timer stuff when kernel_irqchip=off.
    
    Cc: Paolo Bonzini <pbonzini@redhat.com>
    Cc: Radim Krčmář <rkrcmar@redhat.com>
    Cc: Yunhong Jiang <yunhong.jiang@intel.com>
    Signed-off-by: default avatarWanpeng Li <wanpeng.li@hotmail.com>
    Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
    91005300
lapic.c 58.9 KB