From 28867cee754c07b3fa0a679ed2ea394843130217 Mon Sep 17 00:00:00 2001 From: Avi Kivity Date: Mon, 16 Jan 2012 15:08:44 +0200 Subject: KVM: x86 emulator: add 8-bit memory operands Useful for MOVSX/MOVZX. Signed-off-by: Avi Kivity Signed-off-by: Marcelo Tosatti --- arch/x86/kvm/emulate.c | 5 +++++ 1 file changed, 5 insertions(+) (limited to 'arch/x86/kvm/emulate.c') diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c index 0982507b962a..5da6b3619201 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 */ @@ -3656,6 +3658,9 @@ 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; -- cgit v1.2.3 From 2adb5ad9fe1b44d0ae8b00d2bd6568e6163215b3 Mon Sep 17 00:00:00 2001 From: Avi Kivity Date: Mon, 16 Jan 2012 15:08:45 +0200 Subject: KVM: x86 emulator: Remove byte-sized MOVSX/MOVZX hack Currently we treat MOVSX/MOVZX with a byte source as a byte instruction, and change the destination operand size with a hack. Change it to be a word instruction, so the destination receives its natural size, and change the source to be SrcMem8. Signed-off-by: Avi Kivity Signed-off-by: Marcelo Tosatti --- arch/x86/kvm/emulate.c | 13 +++++-------- 1 file changed, 5 insertions(+), 8 deletions(-) (limited to 'arch/x86/kvm/emulate.c') diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c index 5da6b3619201..6eaedac7cf6a 100644 --- a/arch/x86/kvm/emulate.c +++ b/arch/x86/kvm/emulate.c @@ -860,8 +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; @@ -878,7 +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 { @@ -3516,13 +3515,13 @@ 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), @@ -3604,9 +3603,7 @@ 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); -- cgit v1.2.3 From 1a18a69b762374c423305772500f36eb8984ca52 Mon Sep 17 00:00:00 2001 From: Avi Kivity Date: Wed, 1 Feb 2012 12:23:21 +0200 Subject: KVM: x86 emulator: reject SYSENTER in compatibility mode on AMD guests If the guest thinks it's an AMD, it will not have prepared the SYSENTER MSRs, and if the guest executes SYSENTER in compatibility mode, it will fails. Detect this condition and #UD instead, like the spec says. Signed-off-by: Avi Kivity --- arch/x86/kvm/emulate.c | 19 +++++++++++++++++++ 1 file changed, 19 insertions(+) (limited to 'arch/x86/kvm/emulate.c') diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c index 6eaedac7cf6a..71450aca3b86 100644 --- a/arch/x86/kvm/emulate.c +++ b/arch/x86/kvm/emulate.c @@ -1892,6 +1892,17 @@ 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; @@ -2008,6 +2019,14 @@ 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. */ -- cgit v1.2.3 From 7f3d35fddd173e52886d03bc34b5b5d6f5bea343 Mon Sep 17 00:00:00 2001 From: Kevin Wolf Date: Wed, 8 Feb 2012 14:34:38 +0100 Subject: KVM: x86 emulator: Fix task switch privilege checks Currently, all task switches check privileges against the DPL of the TSS. This is only correct for jmp/call to a TSS. If a task gate is used, the DPL of this take gate is used for the check instead. Exceptions, external interrupts and iret shouldn't perform any check. [avi: kill kvm-kmod remnants] Signed-off-by: Kevin Wolf Signed-off-by: Avi Kivity --- arch/x86/kvm/emulate.c | 53 +++++++++++++++++++++++++++++++++++++++++++------- 1 file changed, 46 insertions(+), 7 deletions(-) (limited to 'arch/x86/kvm/emulate.c') diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c index 71450aca3b86..fa310a48591c 100644 --- a/arch/x86/kvm/emulate.c +++ b/arch/x86/kvm/emulate.c @@ -1152,6 +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) { @@ -2421,7 +2437,7 @@ 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; @@ -2443,12 +2459,35 @@ 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)) || @@ -2501,7 +2540,7 @@ 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; @@ -2509,7 +2548,7 @@ 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) -- cgit v1.2.3 From 66b0ab8fac1031ffc70eb77491048339f2717a54 Mon Sep 17 00:00:00 2001 From: Kevin Wolf Date: Wed, 8 Feb 2012 14:34:39 +0100 Subject: KVM: x86 emulator: VM86 segments must have DPL 3 Setting the segment DPL to 0 for at least the VM86 code segment makes the VM entry fail on VMX. Signed-off-by: Kevin Wolf Signed-off-by: Avi Kivity --- arch/x86/kvm/emulate.c | 2 ++ 1 file changed, 2 insertions(+) (limited to 'arch/x86/kvm/emulate.c') diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c index fa310a48591c..b19e9fffe582 100644 --- a/arch/x86/kvm/emulate.c +++ b/arch/x86/kvm/emulate.c @@ -1244,6 +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; } -- cgit v1.2.3 From 4cee4798a304ee1ea579423ca048f16ceaccdfb5 Mon Sep 17 00:00:00 2001 From: Kevin Wolf Date: Wed, 8 Feb 2012 14:34:41 +0100 Subject: KVM: x86 emulator: Allow PM/VM86 switch during task switch Task switches can switch between Protected Mode and VM86. The current mode must be updated during the task switch emulation so that the new segment selectors are interpreted correctly. In order to let privilege checks succeed, rflags needs to be updated in the vcpu struct as this causes a CPL update. Signed-off-by: Kevin Wolf Signed-off-by: Avi Kivity --- arch/x86/kvm/emulate.c | 20 ++++++++++++++++++++ 1 file changed, 20 insertions(+) (limited to 'arch/x86/kvm/emulate.c') diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c index b19e9fffe582..83756223f8aa 100644 --- a/arch/x86/kvm/emulate.c +++ b/arch/x86/kvm/emulate.c @@ -2344,6 +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; @@ -2365,6 +2367,24 @@ static int load_state_from_tss32(struct x86_emulate_ctxt *ctxt, set_segment_selector(ctxt, tss->fs, VCPU_SREG_FS); 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 -- cgit v1.2.3