tree c3f93d577fe10dfad4d3e1787069595b6d6782d9
parent 9a9abf6b612709f67b9e3852554191541631d075
author Nadav Amit <namit@cs.technion.ac.il> 1414922097 +0200
committer Paolo Bonzini <pbonzini@redhat.com> 1415371450 +0100

KVM: x86: Remove redundant and incorrect cpl check on task-switch

Task-switch emulation checks the privilege level prior to performing the
task-switch.  This check is incorrect in the case of task-gates, in which the
tss.dpl is ignored, and can cause superfluous exceptions.  Moreover this check
is unnecassary, since the CPU checks the privilege levels prior to exiting.
Intel SDM 25.4.2 says "If CALL or JMP accesses a TSS descriptor directly
outside IA-32e mode, privilege levels are checked on the TSS descriptor" prior
to exiting.  AMD 15.14.1 says "The intercept is checked before the task switch
takes place but after the incoming TSS and task gate (if one was involved) have
been checked for correctness."

This patch removes the CPL checks for CALL and JMP.

Signed-off-by: Nadav Amit <namit@cs.technion.ac.il>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>