Commit 1217c0c7 authored by Nadav Amit's avatar Nadav Amit Committed by Ben Hutchings

KVM: x86: Inter-privilege level ret emulation is not implemeneted

commit 9e8919ae upstream.

Return unhandlable error on inter-privilege level ret instruction.  This is
since the current emulation does not check the privilege level correctly when
loading the CS, and does not pop RSP/SS as needed.
Signed-off-by: default avatarNadav Amit <namit@cs.technion.ac.il>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
Signed-off-by: default avatarBen Hutchings <ben@decadent.org.uk>
parent 73886aa0
...@@ -1818,6 +1818,7 @@ static int em_ret_far(struct x86_emulate_ctxt *ctxt) ...@@ -1818,6 +1818,7 @@ static int em_ret_far(struct x86_emulate_ctxt *ctxt)
{ {
int rc; int rc;
unsigned long cs; unsigned long cs;
int cpl = ctxt->ops->cpl(ctxt);
rc = emulate_pop(ctxt, &ctxt->_eip, ctxt->op_bytes); rc = emulate_pop(ctxt, &ctxt->_eip, ctxt->op_bytes);
if (rc != X86EMUL_CONTINUE) if (rc != X86EMUL_CONTINUE)
...@@ -1827,6 +1828,9 @@ static int em_ret_far(struct x86_emulate_ctxt *ctxt) ...@@ -1827,6 +1828,9 @@ static int em_ret_far(struct x86_emulate_ctxt *ctxt)
rc = emulate_pop(ctxt, &cs, ctxt->op_bytes); rc = emulate_pop(ctxt, &cs, ctxt->op_bytes);
if (rc != X86EMUL_CONTINUE) if (rc != X86EMUL_CONTINUE)
return rc; return rc;
/* Outer-privilege level return is not implemented */
if (ctxt->mode >= X86EMUL_MODE_PROT16 && (cs & 3) > cpl)
return X86EMUL_UNHANDLEABLE;
rc = load_segment_descriptor(ctxt, (u16)cs, VCPU_SREG_CS); rc = load_segment_descriptor(ctxt, (u16)cs, VCPU_SREG_CS);
return rc; return rc;
} }
......
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