From: Magnus Kulke <[email protected]> Connect the x86 instruction decoder and emulator to the MSHV backend to handle intercepted instructions. This enables software emulation of MMIO operations in MSHV guests. MSHV has a translate_gva hypercall that is used to accessing the physical guest memory.
A guest might read from unmapped memory regions (e.g. OVMF will probe 0xfed40000 for a vTPM). In those cases 0xFF bytes is returned instead of aborting the execution. Signed-off-by: Magnus Kulke <[email protected]> Link: https://lore.kernel.org/r/[email protected] [mshv.h/mshv_int.h split. - Paolo] Signed-off-by: Paolo Bonzini <[email protected]> --- include/system/mshv_int.h | 4 ++ accel/mshv/mem.c | 65 +++++++++++++++++ target/i386/mshv/mshv-cpu.c | 135 ++++++++++++++++++++++++++++++++++++ 3 files changed, 204 insertions(+) diff --git a/include/system/mshv_int.h b/include/system/mshv_int.h index 66494383134..b29d39911db 100644 --- a/include/system/mshv_int.h +++ b/include/system/mshv_int.h @@ -101,6 +101,10 @@ typedef struct MshvMemoryRegion { bool readonly; } MshvMemoryRegion; +int mshv_guest_mem_read(uint64_t gpa, uint8_t *data, uintptr_t size, + bool is_secure_mode, bool instruction_fetch); +int mshv_guest_mem_write(uint64_t gpa, const uint8_t *data, uintptr_t size, + bool is_secure_mode); void mshv_set_phys_mem(MshvMemoryListener *mml, MemoryRegionSection *section, bool add); diff --git a/accel/mshv/mem.c b/accel/mshv/mem.c index a0a40eb3333..e55c38d4db9 100644 --- a/accel/mshv/mem.c +++ b/accel/mshv/mem.c @@ -59,6 +59,71 @@ static int map_or_unmap(int vm_fd, const MshvMemoryRegion *mr, bool map) return set_guest_memory(vm_fd, ®ion); } +static int handle_unmapped_mmio_region_read(uint64_t gpa, uint64_t size, + uint8_t *data) +{ + warn_report("read from unmapped mmio region gpa=0x%lx size=%lu", gpa, size); + + if (size == 0 || size > 8) { + error_report("invalid size %lu for reading from unmapped mmio region", + size); + return -1; + } + + memset(data, 0xFF, size); + + return 0; +} + +int mshv_guest_mem_read(uint64_t gpa, uint8_t *data, uintptr_t size, + bool is_secure_mode, bool instruction_fetch) +{ + int ret; + MemTxAttrs memattr = { .secure = is_secure_mode }; + + if (instruction_fetch) { + trace_mshv_insn_fetch(gpa, size); + } else { + trace_mshv_mem_read(gpa, size); + } + + ret = address_space_rw(&address_space_memory, gpa, memattr, (void *)data, + size, false); + if (ret == MEMTX_OK) { + return 0; + } + + if (ret == MEMTX_DECODE_ERROR) { + return handle_unmapped_mmio_region_read(gpa, size, data); + } + + error_report("failed to read guest memory at 0x%lx", gpa); + return -1; +} + +int mshv_guest_mem_write(uint64_t gpa, const uint8_t *data, uintptr_t size, + bool is_secure_mode) +{ + int ret; + MemTxAttrs memattr = { .secure = is_secure_mode }; + + trace_mshv_mem_write(gpa, size); + ret = address_space_rw(&address_space_memory, gpa, memattr, (void *)data, + size, true); + if (ret == MEMTX_OK) { + return 0; + } + + if (ret == MEMTX_DECODE_ERROR) { + warn_report("write to unmapped mmio region gpa=0x%lx size=%lu", gpa, + size); + return 0; + } + + error_report("Failed to write guest memory"); + return -1; +} + static int set_memory(const MshvMemoryRegion *mshv_mr, bool add) { int ret = 0; diff --git a/target/i386/mshv/mshv-cpu.c b/target/i386/mshv/mshv-cpu.c index 1f43dfc58ac..424ebdb1228 100644 --- a/target/i386/mshv/mshv-cpu.c +++ b/target/i386/mshv/mshv-cpu.c @@ -104,6 +104,47 @@ static enum hv_register_name FPU_REGISTER_NAMES[26] = { HV_X64_REGISTER_XMM_CONTROL_STATUS, }; +static int translate_gva(const CPUState *cpu, uint64_t gva, uint64_t *gpa, + uint64_t flags) +{ + int ret; + int cpu_fd = mshv_vcpufd(cpu); + int vp_index = cpu->cpu_index; + + hv_input_translate_virtual_address in = { 0 }; + hv_output_translate_virtual_address out = { 0 }; + struct mshv_root_hvcall args = {0}; + uint64_t gva_page = gva >> HV_HYP_PAGE_SHIFT; + + in.vp_index = vp_index; + in.control_flags = flags; + in.gva_page = gva_page; + + /* create the hvcall envelope */ + args.code = HVCALL_TRANSLATE_VIRTUAL_ADDRESS; + args.in_sz = sizeof(in); + args.in_ptr = (uint64_t) ∈ + args.out_sz = sizeof(out); + args.out_ptr = (uint64_t) &out; + + /* perform the call */ + ret = mshv_hvcall(cpu_fd, &args); + if (ret < 0) { + error_report("Failed to invoke gva->gpa translation"); + return -errno; + } + + if (out.translation_result.result_code != HV_TRANSLATE_GVA_SUCCESS) { + error_report("Failed to translate gva (" TARGET_FMT_lx ") to gpa", gva); + return -1; + } + + *gpa = ((out.gpa_page << HV_HYP_PAGE_SHIFT) + | (gva & ~(uint64_t)HV_HYP_PAGE_MASK)); + + return 0; +} + int mshv_set_generic_regs(const CPUState *cpu, const hv_register_assoc *assocs, size_t n_regs) { @@ -1006,8 +1047,102 @@ int mshv_create_vcpu(int vm_fd, uint8_t vp_index, int *cpu_fd) return 0; } +static int guest_mem_read_with_gva(const CPUState *cpu, uint64_t gva, + uint8_t *data, uintptr_t size, + bool fetch_instruction) +{ + int ret; + uint64_t gpa, flags; + + flags = HV_TRANSLATE_GVA_VALIDATE_READ; + ret = translate_gva(cpu, gva, &gpa, flags); + if (ret < 0) { + error_report("failed to translate gva to gpa"); + return -1; + } + + ret = mshv_guest_mem_read(gpa, data, size, false, fetch_instruction); + if (ret < 0) { + error_report("failed to read from guest memory"); + return -1; + } + + return 0; +} + +static int guest_mem_write_with_gva(const CPUState *cpu, uint64_t gva, + const uint8_t *data, uintptr_t size) +{ + int ret; + uint64_t gpa, flags; + + flags = HV_TRANSLATE_GVA_VALIDATE_WRITE; + ret = translate_gva(cpu, gva, &gpa, flags); + if (ret < 0) { + error_report("failed to translate gva to gpa"); + return -1; + } + ret = mshv_guest_mem_write(gpa, data, size, false); + if (ret < 0) { + error_report("failed to write to guest memory"); + return -1; + } + return 0; +} + +static void write_mem(CPUState *cpu, void *data, target_ulong addr, int bytes) +{ + if (guest_mem_write_with_gva(cpu, addr, data, bytes) < 0) { + error_report("failed to write memory"); + abort(); + } +} + +static void fetch_instruction(CPUState *cpu, void *data, + target_ulong addr, int bytes) +{ + if (guest_mem_read_with_gva(cpu, addr, data, bytes, true) < 0) { + error_report("failed to fetch instruction"); + abort(); + } +} + +static void read_mem(CPUState *cpu, void *data, target_ulong addr, int bytes) +{ + if (guest_mem_read_with_gva(cpu, addr, data, bytes, false) < 0) { + error_report("failed to read memory"); + abort(); + } +} + +static void read_segment_descriptor(CPUState *cpu, + struct x86_segment_descriptor *desc, + enum X86Seg seg_idx) +{ + bool ret; + X86CPU *x86_cpu = X86_CPU(cpu); + CPUX86State *env = &x86_cpu->env; + SegmentCache *seg = &env->segs[seg_idx]; + x86_segment_selector sel = { .sel = seg->selector & 0xFFFF }; + + ret = x86_read_segment_descriptor(cpu, desc, sel); + if (ret == false) { + error_report("failed to read segment descriptor"); + abort(); + } +} + +static const struct x86_emul_ops mshv_x86_emul_ops = { + .fetch_instruction = fetch_instruction, + .read_mem = read_mem, + .write_mem = write_mem, + .read_segment_descriptor = read_segment_descriptor, +}; + void mshv_init_mmio_emu(void) { + init_decoder(); + init_emu(&mshv_x86_emul_ops); } void mshv_arch_init_vcpu(CPUState *cpu) -- 2.51.0
