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| author | Wanpeng Li <wanpeng.li@hotmail.com> | 2016-08-03 12:04:12 +0800 |
|---|---|---|
| committer | Paolo Bonzini <pbonzini@redhat.com> | 2016-08-04 14:21:43 +0200 |
| commit | 910053002ef1fdc1d42b7015d5b2400172f43e42 (patch) | |
| tree | 4a5a71503aa0f5bb68ea334e5a3daa0feff647e0 /arch/x86/kvm/lapic.c | |
| parent | 055b6ae95e14326a514334a0a8528a40cd629d10 (diff) | |
| download | lwn-910053002ef1fdc1d42b7015d5b2400172f43e42.tar.gz lwn-910053002ef1fdc1d42b7015d5b2400172f43e42.zip | |
KVM: lapic: fix access preemption timer stuff even if kernel_irqchip=off
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: Wanpeng Li <wanpeng.li@hotmail.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'arch/x86/kvm/lapic.c')
| -rw-r--r-- | arch/x86/kvm/lapic.c | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c index 730cf174090a..b62c85229711 100644 --- a/arch/x86/kvm/lapic.c +++ b/arch/x86/kvm/lapic.c @@ -1349,6 +1349,9 @@ static void start_sw_tscdeadline(struct kvm_lapic *apic) bool kvm_lapic_hv_timer_in_use(struct kvm_vcpu *vcpu) { + if (!lapic_in_kernel(vcpu)) + return false; + return vcpu->arch.apic->lapic_timer.hv_timer_in_use; } EXPORT_SYMBOL_GPL(kvm_lapic_hv_timer_in_use); |