KVM: VMX: Fix kvm_set_shared_msr() called in preemptible context
authorAvi Kivity <avi@redhat.com>
Wed, 18 Apr 2012 12:03:04 +0000 (15:03 +0300)
committerMarcelo Tosatti <mtosatti@redhat.com>
Thu, 19 Apr 2012 02:42:27 +0000 (23:42 -0300)
commit2225fd56049643c1a7d645c0ce9d499d43c7974e
tree968ee8ee689d619c663d49ad5f7cc150d38daab5
parent32f6daad4651a748a58a3ab6da0611862175722f
KVM: VMX: Fix kvm_set_shared_msr() called in preemptible context

kvm_set_shared_msr() may not be called in preemptible context,
but vmx_set_msr() does so:

  BUG: using smp_processor_id() in preemptible [00000000] code: qemu-kvm/22713
  caller is kvm_set_shared_msr+0x32/0xa0 [kvm]
  Pid: 22713, comm: qemu-kvm Not tainted 3.4.0-rc3+ #39
  Call Trace:
   [<ffffffff8131fa82>] debug_smp_processor_id+0xe2/0x100
   [<ffffffffa0328ae2>] kvm_set_shared_msr+0x32/0xa0 [kvm]
   [<ffffffffa03a103b>] vmx_set_msr+0x28b/0x2d0 [kvm_intel]
   ...

Making kvm_set_shared_msr() work in preemptible is cleaner, but
it's used in the fast path.  Making two variants is overkill, so
this patch just disables preemption around the call.

Reported-by: Dave Jones <davej@redhat.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
arch/x86/kvm/vmx.c