KVM: x86: Prevent deadlock against tk_core.seq

syzbot reported a possible deadlock in pvclock_gtod_notify():

CPU 0  		  	   	    	    CPU 1
write_seqcount_begin(&tk_core.seq);
  pvclock_gtod_notify()			    spin_lock(&pool->lock);
    queue_work(..., &pvclock_gtod_work)	    ktime_get()
     spin_lock(&pool->lock);		      do {
     						seq = read_seqcount_begin(tk_core.seq)
						...
				              } while (read_seqcount_retry(&tk_core.seq, seq);

While this is unlikely to happen, it's possible.

Delegate queue_work() to irq_work() which postpones it until the
tk_core.seq write held region is left and interrupts are reenabled.

Fixes: 16e8d74d2da9 ("KVM: x86: notifier for clocksource changes")
Reported-by: [email protected]
Signed-off-by: Thomas Gleixner <[email protected]>
Message-Id: <[email protected]>
Signed-off-by: Paolo Bonzini <[email protected]>

0 files changed, 0 insertions, 0 deletions