KVM: x86: do not check CS.DPL against RPL during task switch

This reverts the check added by commit 5045b468037d (KVM: x86: check CS.DPL
against RPL during task switch, 2014-05-15).  Although the CS.DPL=CS.RPL
check is mentioned in table 7-1 of the SDM as causing a #TSS exception,
it is not mentioned in table 6-6 that lists "invalid TSS conditions"
which cause #TSS exceptions. In fact it causes some tests to fail, which
pass on bare-metal.

Keep the rest of the commit, since we will find new uses for it in 3.18.

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

1 files changed, 0 insertions, 3 deletions

diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index ef117b842334..03954f7900f5 100644
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -1491,9 +1491,6 @@ static int __load_segment_descriptor(struct x86_emulate_ctxt *ctxt,
                         goto exception;
                 break;
         case VCPU_SREG_CS:
-                if (in_task_switch && rpl != dpl)
-                        goto exception;
-
                 if (!(seg_desc.type & 8))
                         goto exception;