From: Nadav Amit Date: Sun, 15 Jun 2014 13:12:59 +0000 (+0300) Subject: KVM: x86: Inter-privilege level ret emulation is not implemeneted X-Git-Tag: v3.2.64~235 X-Git-Url: https://git.openpandora.org/cgi-bin/gitweb.cgi?p=pandora-kernel.git;a=commitdiff_plain;h=1217c0c7df80f3663a67473e8d25ab06dbd41fb9 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 Signed-off-by: Paolo Bonzini Signed-off-by: Ben Hutchings --- diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c index f5302da9af21..638cab52ff28 100644 --- a/arch/x86/kvm/emulate.c +++ b/arch/x86/kvm/emulate.c @@ -1818,6 +1818,7 @@ static int em_ret_far(struct x86_emulate_ctxt *ctxt) { int rc; unsigned long cs; + int cpl = ctxt->ops->cpl(ctxt); rc = emulate_pop(ctxt, &ctxt->_eip, ctxt->op_bytes); if (rc != X86EMUL_CONTINUE) @@ -1827,6 +1828,9 @@ static int em_ret_far(struct x86_emulate_ctxt *ctxt) rc = emulate_pop(ctxt, &cs, ctxt->op_bytes); if (rc != X86EMUL_CONTINUE) 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); return rc; }