x86/bugs: Make Safe-RET robust against interrupt injection
In the Linux kernel, the following vulnerability has been resolved:
x86/bugs: Make Safe-RET robust against interrupt injection
An attacker injecting interrupts while the Safe-RET mitigation executes
on machines affected by SRSO can neutralize the safe return sequence,
potentially leading to data leakage through speculative execution.
Fixup register state as if the Safe-RET sequence executed successfully
by "emulating" it, in a manner of speaking, and avoid executing a RET
instruction after returning from the interrupt.
