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authorWanpeng Li <wanpeng.li@hotmail.com>2016-07-06 18:29:58 +0800
committerYunhong Jiang <yunhong.jiang@linux.intel.com>2016-07-18 08:10:21 -0700
commitae6912551e1bc31e4b846221b7cf5ec2aac76104 (patch)
tree791853c390e7e1e2b0f2f91a1acb7c5bdf13caf3 /kernel/arch/x86/.gitignore
parentc81c5f9e9856d3149ec81c099dfddca212a50e54 (diff)
KVM: nVMX: avoid incorrect preemption timer vmexit in nested guest
The preemption timer for nested VMX is emulated by hrtimer which is started on L2 entry, stopped on L2 exit and evaluated via the check_nested_events hook. However, nested_vmx_exit_handled is always returning true for preemption timer vmexit. Then, the L1 preemption timer vmexit is captured and be treated as a L2 preemption timer vmexit, causing NULL pointer dereferences or worse in the L1 guest's vmexit handler: BUG: unable to handle kernel NULL pointer dereference at (null) IP: [< (null)>] (null) PGD 0 Oops: 0010 [#1] SMP Call Trace: ? kvm_lapic_expired_hv_timer+0x47/0x90 [kvm] handle_preemption_timer+0xe/0x20 [kvm_intel] vmx_handle_exit+0x169/0x15a0 [kvm_intel] ? kvm_arch_vcpu_ioctl_run+0xd5d/0x19d0 [kvm] kvm_arch_vcpu_ioctl_run+0xdee/0x19d0 [kvm] ? kvm_arch_vcpu_ioctl_run+0xd5d/0x19d0 [kvm] ? vcpu_load+0x1c/0x60 [kvm] ? kvm_arch_vcpu_load+0x57/0x260 [kvm] kvm_vcpu_ioctl+0x2d3/0x7c0 [kvm] do_vfs_ioctl+0x96/0x6a0 ? __fget_light+0x2a/0x90 SyS_ioctl+0x79/0x90 do_syscall_64+0x68/0x180 entry_SYSCALL64_slow_path+0x25/0x25 Code: Bad RIP value. RIP [< (null)>] (null) RSP <ffff8800b5263c48> CR2: 0000000000000000 ---[ end trace 9c70c48b1a2bc66e ]--- This can be reproduced readily by preemption timer enabled on L0 and disabled on L1. Return false since preemption timer vmexits must never be reflected to L2. Cc: Paolo Bonzini <pbonzini@redhat.com> Cc: Radim Krčmář <rkrcmar@redhat.com> Cc: Yunhong Jiang <yunhong.jiang@intel.com> Cc: Jan Kiszka <jan.kiszka@siemens.com> Cc: Haozhong Zhang <haozhong.zhang@intel.com> Signed-off-by: Wanpeng Li <wanpeng.li@hotmail.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Change-Id: Iaffcd503666879e8157c8559876330110a66e5c4 upstream-status: backport Signed-off-by: Yunhong Jiang <yunhong.jiang@linux.intel.com>
Diffstat (limited to 'kernel/arch/x86/.gitignore')
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