diff options
Diffstat (limited to 'arch/x86/kvm/emulate.c')
| -rw-r--r-- | arch/x86/kvm/emulate.c | 163 |
1 files changed, 148 insertions, 15 deletions
diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c index 05a562b..8375622 100644 --- a/arch/x86/kvm/emulate.c +++ b/arch/x86/kvm/emulate.c @@ -57,6 +57,7 @@ #define OpDS 23ull /* DS */ #define OpFS 24ull /* FS */ #define OpGS 25ull /* GS */ +#define OpMem8 26ull /* 8-bit zero extended memory operand */ #define OpBits 5 /* Width of operand field */ #define OpMask ((1ull << OpBits) - 1) @@ -101,6 +102,7 @@ #define SrcAcc (OpAcc << SrcShift) #define SrcImmU16 (OpImmU16 << SrcShift) #define SrcDX (OpDX << SrcShift) +#define SrcMem8 (OpMem8 << SrcShift) #define SrcMask (OpMask << SrcShift) #define BitOp (1<<11) #define MemAbs (1<<12) /* Memory operand is absolute displacement */ @@ -858,8 +860,7 @@ static void write_sse_reg(struct x86_emulate_ctxt *ctxt, sse128_t *data, } static void decode_register_operand(struct x86_emulate_ctxt *ctxt, - struct operand *op, - int inhibit_bytereg) + struct operand *op) { unsigned reg = ctxt->modrm_reg; int highbyte_regs = ctxt->rex_prefix == 0; @@ -876,7 +877,7 @@ static void decode_register_operand(struct x86_emulate_ctxt *ctxt, } op->type = OP_REG; - if ((ctxt->d & ByteOp) && !inhibit_bytereg) { + if (ctxt->d & ByteOp) { op->addr.reg = decode_register(reg, ctxt->regs, highbyte_regs); op->bytes = 1; } else { @@ -1151,6 +1152,22 @@ static int pio_in_emulated(struct x86_emulate_ctxt *ctxt, return 1; } +static int read_interrupt_descriptor(struct x86_emulate_ctxt *ctxt, + u16 index, struct desc_struct *desc) +{ + struct desc_ptr dt; + ulong addr; + + ctxt->ops->get_idt(ctxt, &dt); + + if (dt.size < index * 8 + 7) + return emulate_gp(ctxt, index << 3 | 0x2); + + addr = dt.address + index * 8; + return ctxt->ops->read_std(ctxt, addr, desc, sizeof *desc, + &ctxt->exception); +} + static void get_descriptor_table_ptr(struct x86_emulate_ctxt *ctxt, u16 selector, struct desc_ptr *dt) { @@ -1227,6 +1244,8 @@ static int load_segment_descriptor(struct x86_emulate_ctxt *ctxt, seg_desc.type = 3; seg_desc.p = 1; seg_desc.s = 1; + if (ctxt->mode == X86EMUL_MODE_VM86) + seg_desc.dpl = 3; goto load; } @@ -1891,6 +1910,62 @@ setup_syscalls_segments(struct x86_emulate_ctxt *ctxt, ss->p = 1; } +static bool vendor_intel(struct x86_emulate_ctxt *ctxt) +{ + u32 eax, ebx, ecx, edx; + + eax = ecx = 0; + return ctxt->ops->get_cpuid(ctxt, &eax, &ebx, &ecx, &edx) + && ebx == X86EMUL_CPUID_VENDOR_GenuineIntel_ebx + && ecx == X86EMUL_CPUID_VENDOR_GenuineIntel_ecx + && edx == X86EMUL_CPUID_VENDOR_GenuineIntel_edx; +} + +static bool em_syscall_is_enabled(struct x86_emulate_ctxt *ctxt) +{ + struct x86_emulate_ops *ops = ctxt->ops; + u32 eax, ebx, ecx, edx; + + /* + * syscall should always be enabled in longmode - so only become + * vendor specific (cpuid) if other modes are active... + */ + if (ctxt->mode == X86EMUL_MODE_PROT64) + return true; + + eax = 0x00000000; + ecx = 0x00000000; + if (ops->get_cpuid(ctxt, &eax, &ebx, &ecx, &edx)) { + /* + * Intel ("GenuineIntel") + * remark: Intel CPUs only support "syscall" in 64bit + * longmode. Also an 64bit guest with a + * 32bit compat-app running will #UD !! While this + * behaviour can be fixed (by emulating) into AMD + * response - CPUs of AMD can't behave like Intel. + */ + if (ebx == X86EMUL_CPUID_VENDOR_GenuineIntel_ebx && + ecx == X86EMUL_CPUID_VENDOR_GenuineIntel_ecx && + edx == X86EMUL_CPUID_VENDOR_GenuineIntel_edx) + return false; + + /* AMD ("AuthenticAMD") */ + if (ebx == X86EMUL_CPUID_VENDOR_AuthenticAMD_ebx && + ecx == X86EMUL_CPUID_VENDOR_AuthenticAMD_ecx && + edx == X86EMUL_CPUID_VENDOR_AuthenticAMD_edx) + return true; + + /* AMD ("AMDisbetter!") */ + if (ebx == X86EMUL_CPUID_VENDOR_AMDisbetterI_ebx && + ecx == X86EMUL_CPUID_VENDOR_AMDisbetterI_ecx && + edx == X86EMUL_CPUID_VENDOR_AMDisbetterI_edx) + return true; + } + + /* default: (not Intel, not AMD), apply Intel's stricter rules... */ + return false; +} + static int em_syscall(struct x86_emulate_ctxt *ctxt) { struct x86_emulate_ops *ops = ctxt->ops; @@ -1904,9 +1979,15 @@ static int em_syscall(struct x86_emulate_ctxt *ctxt) ctxt->mode == X86EMUL_MODE_VM86) return emulate_ud(ctxt); + if (!(em_syscall_is_enabled(ctxt))) + return emulate_ud(ctxt); + ops->get_msr(ctxt, MSR_EFER, &efer); setup_syscalls_segments(ctxt, &cs, &ss); + if (!(efer & EFER_SCE)) + return emulate_ud(ctxt); + ops->get_msr(ctxt, MSR_STAR, &msr_data); msr_data >>= 32; cs_sel = (u16)(msr_data & 0xfffc); @@ -1956,6 +2037,14 @@ static int em_sysenter(struct x86_emulate_ctxt *ctxt) if (ctxt->mode == X86EMUL_MODE_REAL) return emulate_gp(ctxt, 0); + /* + * Not recognized on AMD in compat mode (but is recognized in legacy + * mode). + */ + if ((ctxt->mode == X86EMUL_MODE_PROT32) && (efer & EFER_LMA) + && !vendor_intel(ctxt)) + return emulate_ud(ctxt); + /* XXX sysenter/sysexit have not been tested in 64bit mode. * Therefore, we inject an #UD. */ @@ -2255,6 +2344,8 @@ static int load_state_from_tss32(struct x86_emulate_ctxt *ctxt, return emulate_gp(ctxt, 0); ctxt->_eip = tss->eip; ctxt->eflags = tss->eflags | 2; + + /* General purpose registers */ ctxt->regs[VCPU_REGS_RAX] = tss->eax; ctxt->regs[VCPU_REGS_RCX] = tss->ecx; ctxt->regs[VCPU_REGS_RDX] = tss->edx; @@ -2277,6 +2368,24 @@ static int load_state_from_tss32(struct x86_emulate_ctxt *ctxt, set_segment_selector(ctxt, tss->gs, VCPU_SREG_GS); /* + * If we're switching between Protected Mode and VM86, we need to make + * sure to update the mode before loading the segment descriptors so + * that the selectors are interpreted correctly. + * + * Need to get rflags to the vcpu struct immediately because it + * influences the CPL which is checked at least when loading the segment + * descriptors and when pushing an error code to the new kernel stack. + * + * TODO Introduce a separate ctxt->ops->set_cpl callback + */ + if (ctxt->eflags & X86_EFLAGS_VM) + ctxt->mode = X86EMUL_MODE_VM86; + else + ctxt->mode = X86EMUL_MODE_PROT32; + + ctxt->ops->set_rflags(ctxt, ctxt->eflags); + + /* * Now load segment descriptors. If fault happenes at this stage * it is handled in a context of new task */ @@ -2350,7 +2459,7 @@ static int task_switch_32(struct x86_emulate_ctxt *ctxt, } static int emulator_do_task_switch(struct x86_emulate_ctxt *ctxt, - u16 tss_selector, int reason, + u16 tss_selector, int idt_index, int reason, bool has_error_code, u32 error_code) { struct x86_emulate_ops *ops = ctxt->ops; @@ -2372,12 +2481,35 @@ static int emulator_do_task_switch(struct x86_emulate_ctxt *ctxt, /* FIXME: check that next_tss_desc is tss */ - if (reason != TASK_SWITCH_IRET) { - if ((tss_selector & 3) > next_tss_desc.dpl || - ops->cpl(ctxt) > next_tss_desc.dpl) - return emulate_gp(ctxt, 0); + /* + * Check privileges. The three cases are task switch caused by... + * + * 1. jmp/call/int to task gate: Check against DPL of the task gate + * 2. Exception/IRQ/iret: No check is performed + * 3. jmp/call to TSS: Check agains DPL of the TSS + */ + if (reason == TASK_SWITCH_GATE) { + if (idt_index != -1) { + /* Software interrupts */ + struct desc_struct task_gate_desc; + int dpl; + + ret = read_interrupt_descriptor(ctxt, idt_index, + &task_gate_desc); + if (ret != X86EMUL_CONTINUE) + return ret; + + dpl = task_gate_desc.dpl; + if ((tss_selector & 3) > dpl || ops->cpl(ctxt) > dpl) + return emulate_gp(ctxt, (idt_index << 3) | 0x2); + } + } else if (reason != TASK_SWITCH_IRET) { + int dpl = next_tss_desc.dpl; + if ((tss_selector & 3) > dpl || ops->cpl(ctxt) > dpl) + return emulate_gp(ctxt, tss_selector); } + desc_limit = desc_limit_scaled(&next_tss_desc); if (!next_tss_desc.p || ((desc_limit < 0x67 && (next_tss_desc.type & 8)) || @@ -2430,7 +2562,7 @@ static int emulator_do_task_switch(struct x86_emulate_ctxt *ctxt, } int emulator_task_switch(struct x86_emulate_ctxt *ctxt, - u16 tss_selector, int reason, + u16 tss_selector, int idt_index, int reason, bool has_error_code, u32 error_code) { int rc; @@ -2438,7 +2570,7 @@ int emulator_task_switch(struct x86_emulate_ctxt *ctxt, ctxt->_eip = ctxt->eip; ctxt->dst.type = OP_NONE; - rc = emulator_do_task_switch(ctxt, tss_selector, reason, + rc = emulator_do_task_switch(ctxt, tss_selector, idt_index, reason, has_error_code, error_code); if (rc == X86EMUL_CONTINUE) @@ -3463,13 +3595,13 @@ static struct opcode twobyte_table[256] = { I(DstMem | SrcReg | ModRM | BitOp | Lock, em_btr), I(DstReg | SrcMemFAddr | ModRM | Src2FS, em_lseg), I(DstReg | SrcMemFAddr | ModRM | Src2GS, em_lseg), - D(ByteOp | DstReg | SrcMem | ModRM | Mov), D(DstReg | SrcMem16 | ModRM | Mov), + D(DstReg | SrcMem8 | ModRM | Mov), D(DstReg | SrcMem16 | ModRM | Mov), /* 0xB8 - 0xBF */ N, N, G(BitOp, group8), I(DstMem | SrcReg | ModRM | BitOp | Lock | PageTable, em_btc), I(DstReg | SrcMem | ModRM, em_bsf), I(DstReg | SrcMem | ModRM, em_bsr), - D(ByteOp | DstReg | SrcMem | ModRM | Mov), D(DstReg | SrcMem16 | ModRM | Mov), + D(DstReg | SrcMem8 | ModRM | Mov), D(DstReg | SrcMem16 | ModRM | Mov), /* 0xC0 - 0xCF */ D2bv(DstMem | SrcReg | ModRM | Lock), N, D(DstMem | SrcReg | ModRM | Mov), @@ -3551,9 +3683,7 @@ static int decode_operand(struct x86_emulate_ctxt *ctxt, struct operand *op, switch (d) { case OpReg: - decode_register_operand(ctxt, op, - op == &ctxt->dst && - ctxt->twobyte && (ctxt->b == 0xb6 || ctxt->b == 0xb7)); + decode_register_operand(ctxt, op); break; case OpImmUByte: rc = decode_imm(ctxt, op, 1, false); @@ -3605,6 +3735,9 @@ static int decode_operand(struct x86_emulate_ctxt *ctxt, struct operand *op, case OpImm: rc = decode_imm(ctxt, op, imm_size(ctxt), true); break; + case OpMem8: + ctxt->memop.bytes = 1; + goto mem_common; case OpMem16: ctxt->memop.bytes = 2; goto mem_common; |
