[OpenIndiana-discuss] Intel hardware

[russell]

Hi Jerry

About why Intel is vulnerable to Meltdown and AMD, while Intel basically 
licensed the x64 instruction set from AMD the actual implementation of 
those instructions is completely different.

The instruction set for x86 and x64 is targeted at  Complex Instruction 
Set Computers (CISCs) however the underlying architecture of the Intel 
CPU is a hybrid CISC/RISC design. Intel can issue microcode updates to 
alter how x86/x64 instructions are mapped/translated into CISC/RISC 
architecture to fix execution issues and some security issues. As 
already been discussed widely the Meltdown security failure is core CPU 
functionality which has to be programmed around, so that OS Kernel 
Memory has to exist in a separate Virtual Machine from the User 
Programs. When an application needs to access the kernel it makes the 
function call which triggers the OS to save the request before switching 
to the kernel Virtual Machine which can then process the request,  but 
the process is reversed to return the results to the user application. 
Which is why Amazon have issued performance warnings, Microsoft Azure 
customers are complaining about broken servers.

AMD also has a combined CISC/RISC design but it is completely different 
from Intel which is why it is not susceptible to Meltdown and is 
susceptible to only one of the Spectre vulnerabilities.

In respect of ARM processors, Apple designs it own ARM processors which 
is why all their products are effected by Meltdown but only one of the 
standard ARM production cores is known to be susceptible. Equally 
Qualcomm designs its own ARM chips which have be reported to vulnerable 
to Meltdown.

In order to address vulnerabilities in speculative instruction execution 
the CPU should write the information into a separate L1 cache which 
implements process locking to stop other processes from accessing the 
speculative results.

Regards

Russell