linux/arch
Wanpeng Li 55123e3c86 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>
2016-07-11 09:49:26 +02:00
..
alpha lib/GCD.c: use binary GCD algorithm instead of Euclidean 2016-05-20 17:58:30 -07:00
arc Merge branch 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2016-05-25 17:05:40 -07:00
arm KVM: remove kvm_guest_enter/exit wrappers 2016-07-01 11:03:21 +02:00
arm64 KVM: ARM64: Fix typos 2016-06-14 11:16:27 +02:00
avr32 printk/nmi: generic solution for safe printk in NMI 2016-05-20 17:58:30 -07:00
blackfin printk/nmi: generic solution for safe printk in NMI 2016-05-20 17:58:30 -07:00
c6x asm-generic patch for 4.7 2016-05-24 15:24:37 -07:00
cris MTD updates for v4.7: 2016-05-24 11:00:20 -07:00
frv exit_thread: remove empty bodies 2016-05-20 17:58:30 -07:00
h8300 Merge branch 'hash' of git://ftp.sciencehorizons.net/linux 2016-05-28 16:15:25 -07:00
hexagon asm-generic patch for 4.7 2016-05-24 15:24:37 -07:00
ia64 Merge branch 'kbuild' of git://git.kernel.org/pub/scm/linux/kernel/git/mmarek/kbuild 2016-05-26 22:01:22 -07:00
m32r Merge branch 'kbuild' of git://git.kernel.org/pub/scm/linux/kernel/git/mmarek/kbuild 2016-05-26 22:01:22 -07:00
m68k Merge branch 'hash' of git://ftp.sciencehorizons.net/linux 2016-05-28 16:15:25 -07:00
metag Merge branch 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2016-05-25 17:05:40 -07:00
microblaze Merge branch 'hash' of git://ftp.sciencehorizons.net/linux 2016-05-28 16:15:25 -07:00
mips MIPS: KVM: Emulate generic QEMU machine on r6 T&E 2016-07-05 16:09:20 +02:00
mn10300 Merge branch 'kbuild' of git://git.kernel.org/pub/scm/linux/kernel/git/mmarek/kbuild 2016-05-26 22:01:22 -07:00
nios2 Merge branch 'kbuild' of git://git.kernel.org/pub/scm/linux/kernel/git/mmarek/kbuild 2016-05-26 22:01:22 -07:00
openrisc asm-generic patch for 4.7 2016-05-24 15:24:37 -07:00
parisc parisc: Whitespace cleanups in unistd.h 2016-05-25 15:40:49 +02:00
powerpc KVM: remove kvm_guest_enter/exit wrappers 2016-07-01 11:03:21 +02:00
s390 KVM: s390: inject PER i-fetch events on applicable icpts 2016-07-05 12:02:56 +02:00
score asm-generic patch for 4.7 2016-05-24 15:24:37 -07:00
sh Merge branch 'kbuild' of git://git.kernel.org/pub/scm/linux/kernel/git/mmarek/kbuild 2016-05-26 22:01:22 -07:00
sparc Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/sparc 2016-05-31 22:20:56 -07:00
tile Merge branch 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2016-05-25 17:05:40 -07:00
um Merge branch 'for-linus-4.7-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rw/uml 2016-05-27 18:54:59 -07:00
unicore32 Merge branch 'kbuild' of git://git.kernel.org/pub/scm/linux/kernel/git/mmarek/kbuild 2016-05-26 22:01:22 -07:00
x86 KVM: nVMX: avoid incorrect preemption timer vmexit in nested guest 2016-07-11 09:49:26 +02:00
xtensa Merge branch 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2016-05-25 17:05:40 -07:00
.gitignore
Kconfig Merge branch 'hash' of git://ftp.sciencehorizons.net/linux 2016-05-28 16:15:25 -07:00