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authorWanpeng Li <wanpeng.li@hotmail.com>2016-08-03 07:04:12 +0300
committerPaolo Bonzini <pbonzini@redhat.com>2016-08-04 15:21:43 +0300
commit910053002ef1fdc1d42b7015d5b2400172f43e42 (patch)
tree4a5a71503aa0f5bb68ea334e5a3daa0feff647e0 /arch/x86
parent055b6ae95e14326a514334a0a8528a40cd629d10 (diff)
downloadlinux-910053002ef1fdc1d42b7015d5b2400172f43e42.tar.xz
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')
-rw-r--r--arch/x86/kvm/lapic.c3
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);