diff options
| -rw-r--r-- | arch/x86/kvm/x86_emulate.c | 72 |
1 files changed, 71 insertions, 1 deletions
diff --git a/arch/x86/kvm/x86_emulate.c b/arch/x86/kvm/x86_emulate.c index 7a9bddb3ebd..c6663d46f32 100644 --- a/arch/x86/kvm/x86_emulate.c +++ b/arch/x86/kvm/x86_emulate.c @@ -1541,6 +1541,73 @@ emulate_sysenter(struct x86_emulate_ctxt *ctxt) return 0; } +static int +emulate_sysexit(struct x86_emulate_ctxt *ctxt) +{ + struct decode_cache *c = &ctxt->decode; + struct kvm_segment cs, ss; + u64 msr_data; + int usermode; + + /* inject #UD if LOCK prefix is used */ + if (c->lock_prefix) + return -1; + + /* inject #GP if in real mode or paging is disabled */ + if (ctxt->mode == X86EMUL_MODE_REAL + || !(ctxt->vcpu->arch.cr0 & X86_CR0_PE)) { + kvm_inject_gp(ctxt->vcpu, 0); + return -1; + } + + /* sysexit must be called from CPL 0 */ + if (kvm_x86_ops->get_cpl(ctxt->vcpu) != 0) { + kvm_inject_gp(ctxt->vcpu, 0); + return -1; + } + + setup_syscalls_segments(ctxt, &cs, &ss); + + if ((c->rex_prefix & 0x8) != 0x0) + usermode = X86EMUL_MODE_PROT64; + else + usermode = X86EMUL_MODE_PROT32; + + cs.dpl = 3; + ss.dpl = 3; + kvm_x86_ops->get_msr(ctxt->vcpu, MSR_IA32_SYSENTER_CS, &msr_data); + switch (usermode) { + case X86EMUL_MODE_PROT32: + cs.selector = (u16)(msr_data + 16); + if ((msr_data & 0xfffc) == 0x0) { + kvm_inject_gp(ctxt->vcpu, 0); + return -1; + } + ss.selector = (u16)(msr_data + 24); + break; + case X86EMUL_MODE_PROT64: + cs.selector = (u16)(msr_data + 32); + if (msr_data == 0x0) { + kvm_inject_gp(ctxt->vcpu, 0); + return -1; + } + ss.selector = cs.selector + 8; + cs.db = 0; + cs.l = 1; + break; + } + cs.selector |= SELECTOR_RPL_MASK; + ss.selector |= SELECTOR_RPL_MASK; + + kvm_x86_ops->set_segment(ctxt->vcpu, &cs, VCPU_SREG_CS); + kvm_x86_ops->set_segment(ctxt->vcpu, &ss, VCPU_SREG_SS); + + c->eip = ctxt->vcpu->arch.regs[VCPU_REGS_RDX]; + c->regs[VCPU_REGS_RSP] = ctxt->vcpu->arch.regs[VCPU_REGS_RCX]; + + return 0; +} + int x86_emulate_insn(struct x86_emulate_ctxt *ctxt, struct x86_emulate_ops *ops) { @@ -2215,7 +2282,10 @@ twobyte_insn: goto writeback; break; case 0x35: /* sysexit */ - goto cannot_emulate; + if (emulate_sysexit(ctxt) == -1) + goto cannot_emulate; + else + goto writeback; break; case 0x40 ... 0x4f: /* cmov */ c->dst.val = c->dst.orig_val = c->src.val; |