Enumerate AVX Vector Neural Network instructions

Enumerate AVX Vector Neural Network instructions

Add AVX version of the Vector Neural Network (VNNI) Instructions.

A processor supports AVX VNNI instructions if CPUID.0x07.0x1:EAX[4] is
present. The following instructions are available when this feature is
present.
  1. VPDPBUS: Multiply and Add Unsigned and Signed Bytes
  2. VPDPBUSDS: Multiply and Add Unsigned and Signed Bytes with Saturation
  3. VPDPWSSD: Multiply and Add Signed Word Integers
  4. VPDPWSSDS: Multiply and Add Signed Integers with Saturation

The only in-kernel usage of this is kvm passthrough. The CPU feature
flag is shown as "avx_vnni" in /proc/cpuinfo.

This instruction is currently documented in the latest "extensions"
manual (ISE). It will appear in the "main" manual (SDM) in the future.

Signed-off-by: Kyung Min Park <[email protected]>
Signed-off-by: Yang Zhong <[email protected]>
Reviewed-by: Tony Luck <[email protected]>
Message-Id: <20210105004909[email protected]>
Acked-by: Borislav Petkov <[email protected]>
Signed-off-by: Paolo Bonzini <[email protected]>