Ths patch adds IRET instruction (opcode 0xcf). Currently, only IRET in real mode is emulated. Protected mode support is to be added later if needed.
Signed-off-by: Mohammed Gamal <[email protected]> ---- Changes from v1: - Corrected handling of eflags --- arch/x86/kvm/emulate.c | 69 ++++++++++++++++++++++++++++++++++++++++++++++++ 1 files changed, 69 insertions(+), 0 deletions(-) diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c index b38bd8b..e45fd28 100644 --- a/arch/x86/kvm/emulate.c +++ b/arch/x86/kvm/emulate.c @@ -1778,6 +1778,69 @@ static int emulate_popa(struct x86_emulate_ctxt *ctxt, return rc; } +static int emulate_iret_real(struct x86_emulate_ctxt *ctxt, + struct x86_emulate_ops *ops) +{ + struct decode_cache *c = &ctxt->decode; + int rc = X86EMUL_CONTINUE; + unsigned long temp_eip = 0; + unsigned long temp_eflags = 0; + unsigned long mask = EFLG_CF | EFLG_PF | EFLG_AF | EFLG_ZF | EFLG_SF | EFLG_TF | + EFLG_IF | EFLG_DF | EFLG_OF | EFLG_IOPL | EFLG_NT | EFLG_RF | + EFLG_AC | EFLG_ID | (1 << 1); /* Last one is the reserved bit */ + unsigned long vm86_mask = EFLG_VM | EFLG_VIF | EFLG_VIP; + + /* TODO: Add stack limit check */ + + rc = emulate_pop(ctxt, ops, &temp_eip, c->op_bytes); + + if (rc != X86EMUL_CONTINUE) + return rc; + + if (temp_eip & ~0xffff) { + emulate_gp(ctxt, 0); + return X86EMUL_PROPAGATE_FAULT; + } + + c->eip = temp_eip; + + rc = emulate_pop_sreg(ctxt, ops, VCPU_SREG_CS); + + if (rc != X86EMUL_CONTINUE) + return rc; + + rc = emulate_pop(ctxt, ops, &temp_eflags, c->op_bytes); + + if (rc != X86EMUL_CONTINUE) + return rc; + + if (c->op_bytes == 4) { + temp_eflags = ((temp_eflags & mask) | (ctxt->eflags & vm86_mask)); + ctxt->eflags = temp_eflags; + } else if (c->op_bytes == 2) { + temp_eflags &= ~0xfffd; /* Do not clear reserved bit 1 */ + ctxt->eflags |= temp_eflags; + } + + return rc; +} + +static inline int emulate_iret(struct x86_emulate_ctxt *ctxt, + struct x86_emulate_ops* ops) +{ + switch(ctxt->mode) { + case X86EMUL_MODE_REAL: + return emulate_iret_real(ctxt, ops); + case X86EMUL_MODE_VM86: + case X86EMUL_MODE_PROT16: + case X86EMUL_MODE_PROT32: + case X86EMUL_MODE_PROT64: + default: + /* iret from protected mode unimplemented yet */ + return X86EMUL_UNHANDLEABLE; + } +} + static inline int emulate_grp1a(struct x86_emulate_ctxt *ctxt, struct x86_emulate_ops *ops) { @@ -2910,6 +2973,12 @@ special_insn: if (rc != X86EMUL_CONTINUE) goto done; break; + case 0xcf: /* iret */ + rc = emulate_iret(ctxt, ops); + + if (rc != X86EMUL_CONTINUE) + goto done; + break; case 0xd0 ... 0xd1: /* Grp2 */ c->src.val = 1; emulate_grp2(ctxt); -- 1.7.0.4 -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
