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  1. 12 Jul, 2017 35 commits
  3. 05 Jul, 2017 5 commits
    • Greg Kroah-Hartman's avatar
      Linux 4.9.36 · 9f86f302
      Greg Kroah-Hartman authored
      9f86f302
    • Wanpeng Li's avatar
      KVM: nVMX: Fix exception injection · a29fd27c
      Wanpeng Li authored 
      commit d4912215 upstream.

 WARNING: CPU: 3 PID: 2840 at arch/x86/kvm/vmx.c:10966 nested_vmx_vmexit+0xdcd/0xde0 [kvm_intel]
 CPU: 3 PID: 2840 Comm: qemu-system-x86 Tainted: G           OE   4.12.0-rc3+ #23
 RIP: 0010:nested_vmx_vmexit+0xdcd/0xde0 [kvm_intel]
 Call Trace:
  ? kvm_check_async_pf_completion+0xef/0x120 [kvm]
  ? rcu_read_lock_sched_held+0x79/0x80
  vmx_queue_exception+0x104/0x160 [kvm_intel]
  ? vmx_queue_exception+0x104/0x160 [kvm_intel]
  kvm_arch_vcpu_ioctl_run+0x1171/0x1ce0 [kvm]
  ? kvm_arch_vcpu_load+0x47/0x240 [kvm]
  ? kvm_arch_vcpu_load+0x62/0x240 [kvm]
  kvm_vcpu_ioctl+0x384/0x7b0 [kvm]
  ? kvm_vcpu_ioctl+0x384/0x7b0 [kvm]
  ? __fget+0xf3/0x210
  do_vfs_ioctl+0xa4/0x700
  ? __fget+0x114/0x210
  SyS_ioctl+0x79/0x90
  do_syscall_64+0x81/0x220
  entry_SYSCALL64_slow_path+0x25/0x25

This is triggered occasionally by running both win7 and win2016 in L2, in
addition, EPT is disabled on both L1 and L2. It can't be reproduced easily.

Commit 0b6ac343 (KVM: nVMX: Correct handling of exception injection) mentioned
that "KVM wants to inject page-faults which it got to the guest. This function
assumes it is called with the exit reason in vmcs02 being a #PF exception".
Commit e011c663 (KVM: nVMX: Check all exceptions for intercept during delivery to
L2) allows to check all exceptions for intercept during delivery to L2. However,
there is no guarantee the exit reason is exception currently, when there is an
external interrupt occurred on host, maybe a time interrupt for host which should
not be injected to guest, and somewhere queues an exception, then the function
nested_vmx_check_exception() will be called and the vmexit emulation codes will
try to emulate the "Acknowledge interrupt on exit" behavior, the warning is
triggered.

Reusing the exit reason from the L2->L0 vmexit is wrong in this case,
the reason must always be EXCEPTION_NMI when injecting an exception into
L1 as a nested vmexit.

Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Radim Krčmář <rkrcmar@redhat.com>
Signed-off-by: default avatarWanpeng Li <wanpeng.li@hotmail.com>
Fixes: e011c663 ("KVM: nVMX: Check all exceptions for intercept during delivery to L2")
Signed-off-by: default avatarRadim Krčmář <rkrcmar@redhat.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      a29fd27c
    • Radim Krčmář's avatar
      KVM: x86: zero base3 of unusable segments · d1d3756f
      Radim Krčmář authored 
      commit f0367ee1 upstream.

Static checker noticed that base3 could be used uninitialized if the
segment was not present (useable).  Random stack values probably would
not pass VMCS entry checks.
Reported-by: default avatarDan Carpenter <dan.carpenter@oracle.com>
Fixes: 1aa36616 ("KVM: x86 emulator: consolidate segment accessors")
Reviewed-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
Reviewed-by: default avatarDavid Hildenbrand <david@redhat.com>
Signed-off-by: default avatarRadim Krčmář <rkrcmar@redhat.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      d1d3756f
    • Radim Krčmář's avatar
      KVM: x86/vPMU: fix undefined shift in intel_pmu_refresh() · f3c3ec96
      Radim Krčmář authored 
      commit 34b0dadb upstream.

Static analysis noticed that pmu->nr_arch_gp_counters can be 32
(INTEL_PMC_MAX_GENERIC) and therefore cannot be used to shift 'int'.

I didn't add BUILD_BUG_ON for it as we have a better checker.
Reported-by: default avatarDan Carpenter <dan.carpenter@oracle.com>
Fixes: 25462f7f ("KVM: x86/vPMU: Define kvm_pmu_ops to support vPMU function dispatch")
Reviewed-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
Reviewed-by: default avatarDavid Hildenbrand <david@redhat.com>
Signed-off-by: default avatarRadim Krčmář <rkrcmar@redhat.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      f3c3ec96
    • Ladi Prosek's avatar
      KVM: x86: fix emulation of RSM and IRET instructions · 1eeb7942
      Ladi Prosek authored 
      commit 6ed071f0 upstream.

On AMD, the effect of set_nmi_mask called by emulate_iret_real and em_rsm
on hflags is reverted later on in x86_emulate_instruction where hflags are
overwritten with ctxt->emul_flags (the kvm_set_hflags call). This manifests
as a hang when rebooting Windows VMs with QEMU, OVMF, and >1 vcpu.

Instead of trying to merge ctxt->emul_flags into vcpu->arch.hflags after
an instruction is emulated, this commit deletes emul_flags altogether and
makes the emulator access vcpu->arch.hflags using two new accessors. This
way all changes, on the emulator side as well as in functions called from
the emulator and accessing vcpu state with emul_to_vcpu, are preserved.

More details on the bug and its manifestation with Windows and OVMF:

  It's a KVM bug in the interaction between SMI/SMM and NMI, specific to AMD.
  I believe that the SMM part explains why we started seeing this only with
  OVMF.

  KVM masks and unmasks NMI when entering and leaving SMM. When KVM emulates
  the RSM instruction in em_rsm, the set_nmi_mask call doesn't stick because
  later on in x86_emulate_instruction we overwrite arch.hflags with
  ctxt->emul_flags, effectively reverting the effect of the set_nmi_mask call.
  The AMD-specific hflag of interest here is HF_NMI_MASK.

  When rebooting the system, Windows sends an NMI IPI to all but the current
  cpu to shut them down. Only after all of them are parked in HLT will the
  initiating cpu finish the restart. If NMI is masked, other cpus never get
  the memo and the initiating cpu spins forever, waiting for
  hal!HalpInterruptProcessorsStarted to drop. That's the symptom we observe.

Fixes: a584539b ("KVM: x86: pass the whole hflags field to emulator and back")
Signed-off-by: default avatarLadi Prosek <lprosek@redhat.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      1eeb7942
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