diff options
Diffstat (limited to 'target/i386/mshv/x86.c')
| -rw-r--r-- | target/i386/mshv/x86.c | 297 |
1 files changed, 297 insertions, 0 deletions
diff --git a/target/i386/mshv/x86.c b/target/i386/mshv/x86.c new file mode 100644 index 0000000..d574b3b --- /dev/null +++ b/target/i386/mshv/x86.c @@ -0,0 +1,297 @@ +/* + * QEMU MSHV support + * + * Copyright Microsoft, Corp. 2025 + * + * Authors: Magnus Kulke <magnuskulke@microsoft.com> + * + * SPDX-License-Identifier: GPL-2.0-or-later + */ + +#include "qemu/osdep.h" + +#include "cpu.h" +#include "emulate/x86_decode.h" +#include "emulate/x86_emu.h" +#include "qemu/typedefs.h" +#include "qemu/error-report.h" +#include "system/mshv.h" + +/* RW or Exec segment */ +static const uint8_t RWRX_SEGMENT_TYPE = 0x2; +static const uint8_t CODE_SEGMENT_TYPE = 0x8; +static const uint8_t EXPAND_DOWN_SEGMENT_TYPE = 0x4; + +typedef enum CpuMode { + REAL_MODE, + PROTECTED_MODE, + LONG_MODE, +} CpuMode; + +static CpuMode cpu_mode(CPUState *cpu) +{ + enum CpuMode m = REAL_MODE; + + if (x86_is_protected(cpu)) { + m = PROTECTED_MODE; + + if (x86_is_long_mode(cpu)) { + m = LONG_MODE; + } + } + + return m; +} + +static bool segment_type_ro(const SegmentCache *seg) +{ + uint32_t type_ = (seg->flags >> DESC_TYPE_SHIFT) & 15; + return (type_ & (~RWRX_SEGMENT_TYPE)) == 0; +} + +static bool segment_type_code(const SegmentCache *seg) +{ + uint32_t type_ = (seg->flags >> DESC_TYPE_SHIFT) & 15; + return (type_ & CODE_SEGMENT_TYPE) != 0; +} + +static bool segment_expands_down(const SegmentCache *seg) +{ + uint32_t type_ = (seg->flags >> DESC_TYPE_SHIFT) & 15; + + if (segment_type_code(seg)) { + return false; + } + + return (type_ & EXPAND_DOWN_SEGMENT_TYPE) != 0; +} + +static uint32_t segment_limit(const SegmentCache *seg) +{ + uint32_t limit = seg->limit; + uint32_t granularity = (seg->flags & DESC_G_MASK) != 0; + + if (granularity != 0) { + limit = (limit << 12) | 0xFFF; + } + + return limit; +} + +static uint8_t segment_db(const SegmentCache *seg) +{ + return (seg->flags >> DESC_B_SHIFT) & 1; +} + +static uint32_t segment_max_limit(const SegmentCache *seg) +{ + if (segment_db(seg) != 0) { + return 0xFFFFFFFF; + } + return 0xFFFF; +} + +static int linearize(CPUState *cpu, + target_ulong logical_addr, target_ulong *linear_addr, + X86Seg seg_idx) +{ + enum CpuMode mode; + X86CPU *x86_cpu = X86_CPU(cpu); + CPUX86State *env = &x86_cpu->env; + SegmentCache *seg = &env->segs[seg_idx]; + target_ulong base = seg->base; + target_ulong logical_addr_32b; + uint32_t limit; + /* TODO: the emulator will not pass us "write" indicator yet */ + bool write = false; + + mode = cpu_mode(cpu); + + switch (mode) { + case LONG_MODE: + if (__builtin_add_overflow(logical_addr, base, linear_addr)) { + error_report("Address overflow"); + return -1; + } + break; + case PROTECTED_MODE: + case REAL_MODE: + if (segment_type_ro(seg) && write) { + error_report("Cannot write to read-only segment"); + return -1; + } + + logical_addr_32b = logical_addr & 0xFFFFFFFF; + limit = segment_limit(seg); + + if (segment_expands_down(seg)) { + if (logical_addr_32b >= limit) { + error_report("Address exceeds limit (expands down)"); + return -1; + } + + limit = segment_max_limit(seg); + } + + if (logical_addr_32b > limit) { + error_report("Address exceeds limit %u", limit); + return -1; + } + *linear_addr = logical_addr_32b + base; + break; + default: + error_report("Unknown cpu mode: %d", mode); + return -1; + } + + return 0; +} + +bool x86_read_segment_descriptor(CPUState *cpu, + struct x86_segment_descriptor *desc, + x86_segment_selector sel) +{ + target_ulong base; + uint32_t limit; + X86CPU *x86_cpu = X86_CPU(cpu); + CPUX86State *env = &x86_cpu->env; + target_ulong gva; + + memset(desc, 0, sizeof(*desc)); + + /* valid gdt descriptors start from index 1 */ + if (!sel.index && GDT_SEL == sel.ti) { + return false; + } + + if (GDT_SEL == sel.ti) { + base = env->gdt.base; + limit = env->gdt.limit; + } else { + base = env->ldt.base; + limit = env->ldt.limit; + } + + if (sel.index * 8 >= limit) { + return false; + } + + gva = base + sel.index * 8; + emul_ops->read_mem(cpu, desc, gva, sizeof(*desc)); + + return true; +} + +bool x86_read_call_gate(CPUState *cpu, struct x86_call_gate *idt_desc, + int gate) +{ + target_ulong base; + uint32_t limit; + X86CPU *x86_cpu = X86_CPU(cpu); + CPUX86State *env = &x86_cpu->env; + target_ulong gva; + + base = env->idt.base; + limit = env->idt.limit; + + memset(idt_desc, 0, sizeof(*idt_desc)); + if (gate * 8 >= limit) { + perror("call gate exceeds idt limit"); + return false; + } + + gva = base + gate * 8; + emul_ops->read_mem(cpu, idt_desc, gva, sizeof(*idt_desc)); + + return true; +} + +bool x86_is_protected(CPUState *cpu) +{ + X86CPU *x86_cpu = X86_CPU(cpu); + CPUX86State *env = &x86_cpu->env; + uint64_t cr0 = env->cr[0]; + + return cr0 & CR0_PE_MASK; +} + +bool x86_is_real(CPUState *cpu) +{ + return !x86_is_protected(cpu); +} + +bool x86_is_v8086(CPUState *cpu) +{ + X86CPU *x86_cpu = X86_CPU(cpu); + CPUX86State *env = &x86_cpu->env; + return x86_is_protected(cpu) && (env->eflags & VM_MASK); +} + +bool x86_is_long_mode(CPUState *cpu) +{ + X86CPU *x86_cpu = X86_CPU(cpu); + CPUX86State *env = &x86_cpu->env; + uint64_t efer = env->efer; + uint64_t lme_lma = (MSR_EFER_LME | MSR_EFER_LMA); + + return ((efer & lme_lma) == lme_lma); +} + +bool x86_is_long64_mode(CPUState *cpu) +{ + error_report("unimplemented: is_long64_mode()"); + abort(); +} + +bool x86_is_paging_mode(CPUState *cpu) +{ + X86CPU *x86_cpu = X86_CPU(cpu); + CPUX86State *env = &x86_cpu->env; + uint64_t cr0 = env->cr[0]; + + return cr0 & CR0_PG_MASK; +} + +bool x86_is_pae_enabled(CPUState *cpu) +{ + X86CPU *x86_cpu = X86_CPU(cpu); + CPUX86State *env = &x86_cpu->env; + uint64_t cr4 = env->cr[4]; + + return cr4 & CR4_PAE_MASK; +} + +target_ulong linear_addr(CPUState *cpu, target_ulong addr, X86Seg seg) +{ + int ret; + target_ulong linear_addr; + + ret = linearize(cpu, addr, &linear_addr, seg); + if (ret < 0) { + error_report("failed to linearize address"); + abort(); + } + + return linear_addr; +} + +target_ulong linear_addr_size(CPUState *cpu, target_ulong addr, int size, + X86Seg seg) +{ + switch (size) { + case 2: + addr = (uint16_t)addr; + break; + case 4: + addr = (uint32_t)addr; + break; + default: + break; + } + return linear_addr(cpu, addr, seg); +} + +target_ulong linear_rip(CPUState *cpu, target_ulong rip) +{ + return linear_addr(cpu, rip, R_CS); +} |