xen/qspinlock: Don't kick CPU if IRQ is not initialized

The following commit:

  1fb3a8b2cfb2 ("xen/spinlock: Fix locking path engaging too soon under PVHVM.")

... moved the initalization of the kicker interrupt until after
native_cpu_up() is called.

However, when using qspinlocks, a CPU may try to kick another CPU that is
spinning (because it has not yet initialized its kicker interrupt), resulting
in the following crash during boot:

  kernel BUG at /build/linux-Ay7j_C/linux-4.4.0/drivers/xen/events/events_base.c:1210!
  invalid opcode: 0000 [#1] SMP
  ...
  RIP: 0010:[<ffffffff814c97c9>]  [<ffffffff814c97c9>] xen_send_IPI_one+0x59/0x60
  ...
  Call Trace:
   [<ffffffff8102be9e>] xen_qlock_kick+0xe/0x10
   [<ffffffff810cabc2>] __pv_queued_spin_unlock+0xb2/0xf0
   [<ffffffff810ca6d1>] ? __raw_callee_save___pv_queued_spin_unlock+0x11/0x20
   [<ffffffff81052936>] ? check_tsc_warp+0x76/0x150
   [<ffffffff81052aa6>] check_tsc_sync_source+0x96/0x160
   [<ffffffff81051e28>] native_cpu_up+0x3d8/0x9f0
   [<ffffffff8102b315>] xen_hvm_cpu_up+0x35/0x80
   [<ffffffff8108198c>] _cpu_up+0x13c/0x180
   [<ffffffff81081a4a>] cpu_up+0x7a/0xa0
   [<ffffffff81f80dfc>] smp_init+0x7f/0x81
   [<ffffffff81f5a121>] kernel_init_freeable+0xef/0x212
   [<ffffffff81817f30>] ? rest_init+0x80/0x80
   [<ffffffff81817f3e>] kernel_init+0xe/0xe0
   [<ffffffff8182488f>] ret_from_fork+0x3f/0x70
   [<ffffffff81817f30>] ? rest_init+0x80/0x80

To fix this, only send the kick if the target CPU's interrupt has been
initialized. This check isn't racy, because the target is waiting for
the spinlock, so it won't have initialized the interrupt in the
meantime.

Signed-off-by: Ross Lagerwall <[email protected]>
Reviewed-by: Boris Ostrovsky <[email protected]>
Cc: David Vrabel <[email protected]>
Cc: Juergen Gross <[email protected]>
Cc: Konrad Rzeszutek Wilk <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: [email protected]
Cc: [email protected]
Signed-off-by: Ingo Molnar <[email protected]>

0 files changed, 0 insertions, 0 deletions