session in multiple threads w/o locking.. There was a single fpu
context shared per session, if multiple threads were using the session,
and both migrated away, they could corrupt each other's fpu context...
This patch adds a per cpu context and a lock to protect it...
It also tries to better address unloading of the aesni module...
The pause will be removed once the OpenCrypto Framework provides a
better method for draining callers into _newsession...
I first discovered the fpu context sharing issue w/ a flood ping over
an IPsec tunnel between two bhyve machines... The patch in D3015
was used to verify that this fix does fix the issue...
Reviewed by: gnn, kib (both earlier versions)
Differential Revision: https://reviews.freebsd.org/D3016
9d38fd076e