KVM: x86: Inter-privilege level ret emulation is not implemeneted
commit 9e8919ae793f4edfaa29694a70f71a515ae9942a 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: Nadav Amit <namit@cs.technion.ac.il> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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@ -2209,6 +2209,7 @@ static int em_ret_far(struct x86_emulate_ctxt *ctxt)
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{
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int rc;
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unsigned long cs;
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int cpl = ctxt->ops->cpl(ctxt);
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rc = emulate_pop(ctxt, &ctxt->_eip, ctxt->op_bytes);
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if (rc != X86EMUL_CONTINUE)
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@ -2218,6 +2219,9 @@ static int em_ret_far(struct x86_emulate_ctxt *ctxt)
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rc = emulate_pop(ctxt, &cs, ctxt->op_bytes);
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if (rc != X86EMUL_CONTINUE)
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return rc;
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/* Outer-privilege level return is not implemented */
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if (ctxt->mode >= X86EMUL_MODE_PROT16 && (cs & 3) > cpl)
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return X86EMUL_UNHANDLEABLE;
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rc = load_segment_descriptor(ctxt, (u16)cs, VCPU_SREG_CS);
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return rc;
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}
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