Because AES-NI instructions will touch XMM state, corresponding code
must be enclosed within kernel_fpu_begin/end, which used
preempt_disable/enable. So sleep should be prevented between
kernel_fpu_begin/end.
Signed-off-by: Huang Ying <ying.huang@intel.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Because kernel_fpu_begin() and kernel_fpu_end() operations are too
slow, the performance gain of general mode implementation + aes-aesni
is almost all compensated.
The AES-NI support for more modes are implemented as follow:
- Add a new AES algorithm implementation named __aes-aesni without
kernel_fpu_begin/end()
- Use fpu(<mode>(AES)) to provide kenrel_fpu_begin/end() invoking
- Add <mode>(AES) ablkcipher, which uses cryptd(fpu(<mode>(AES))) to
defer cryption to cryptd context in soft_irq context.
Now the ctr, lrw, pcbc and xts support are added.
Performance testing based on dm-crypt shows that cryption time can be
reduced to 50% of general mode implementation + aes-aesni implementation.
Signed-off-by: Huang Ying <ying.huang@intel.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Intel AES-NI is a new set of Single Instruction Multiple Data (SIMD)
instructions that are going to be introduced in the next generation of
Intel processor, as of 2009. These instructions enable fast and secure
data encryption and decryption, using the Advanced Encryption Standard
(AES), defined by FIPS Publication number 197. The architecture
introduces six instructions that offer full hardware support for
AES. Four of them support high performance data encryption and
decryption, and the other two instructions support the AES key
expansion procedure.
The white paper can be downloaded from:
http://softwarecommunity.intel.com/isn/downloads/intelavx/AES-Instructions-Set_WP.pdf
AES may be used in soft_irq context, but MMX/SSE context can not be
touched safely in soft_irq context. So in_interrupt() is checked, if
in IRQ or soft_irq context, the general x86_64 implementation are used
instead.
Signed-off-by: Huang Ying <ying.huang@intel.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
