Author: cem Date: Tue Apr 21 21:34:24 2020 New Revision: 360177 URL: https://svnweb.freebsd.org/changeset/base/360177
Log: vmm(4): Decode and emulate BEXTR Clang 10 -march=native kernels on znver1 emit BEXTR for APIC reads, apparently. Decode and emulate the instruction. Reviewed by: grehan Differential Revision: https://reviews.freebsd.org/D24463 Modified: head/sys/amd64/vmm/vmm_instruction_emul.c Modified: head/sys/amd64/vmm/vmm_instruction_emul.c ============================================================================== --- head/sys/amd64/vmm/vmm_instruction_emul.c Tue Apr 21 21:33:06 2020 (r360176) +++ head/sys/amd64/vmm/vmm_instruction_emul.c Tue Apr 21 21:34:24 2020 (r360177) @@ -84,6 +84,7 @@ enum { VIE_OP_TYPE_TWOB_GRP15, VIE_OP_TYPE_ADD, VIE_OP_TYPE_TEST, + VIE_OP_TYPE_BEXTR, VIE_OP_TYPE_LAST }; @@ -95,6 +96,10 @@ enum { #define VIE_OP_F_NO_GLA_VERIFICATION (1 << 4) static const struct vie_op three_byte_opcodes_0f38[256] = { + [0xF7] = { + .op_byte = 0xF7, + .op_type = VIE_OP_TYPE_BEXTR, + }, }; static const struct vie_op two_byte_opcodes[256] = { @@ -1318,6 +1323,83 @@ emulate_test(void *vm, int vcpuid, uint64_t gpa, struc } static int +emulate_bextr(void *vm, int vcpuid, uint64_t gpa, struct vie *vie, + struct vm_guest_paging *paging, mem_region_read_t memread, + mem_region_write_t memwrite, void *arg) +{ + uint64_t src1, src2, dst, rflags; + unsigned start, len; + int error, size; + + size = vie->opsize; + error = EINVAL; + + /* + * VEX.LZ.0F38.W0 F7 /r BEXTR r32a, r/m32, r32b + * VEX.LZ.0F38.W1 F7 /r BEXTR r64a, r/m64, r64b + * + * Destination operand is ModRM:reg. Source operands are ModRM:r/m and + * Vex.vvvv. + * + * Operand size is always 32-bit if not in 64-bit mode (W1 is ignored). + */ + if (size != 4 && paging->cpu_mode != CPU_MODE_64BIT) + size = 4; + + /* + * Extracts contiguous bits from the first /source/ operand (second + * operand) using an index and length specified in the second /source/ + * operand (third operand). + */ + error = memread(vm, vcpuid, gpa, &src1, size, arg); + if (error) + return (error); + error = vie_read_register(vm, vcpuid, gpr_map[vie->vex_reg], &src2); + if (error) + return (error); + error = vie_read_register(vm, vcpuid, VM_REG_GUEST_RFLAGS, &rflags); + if (error) + return (error); + + start = (src2 & 0xff); + len = (src2 & 0xff00) >> 8; + + /* If no bits are extracted, the destination register is cleared. */ + dst = 0; + + /* If START exceeds the operand size, no bits are extracted. */ + if (start > size * 8) + goto done; + /* Length is bounded by both the destination size and start offset. */ + if (start + len > size * 8) + len = (size * 8) - start; + if (len == 0) + goto done; + + if (start > 0) + src1 = (src1 >> start); + if (len < 64) + src1 = src1 & ((1ull << len) - 1); + dst = src1; + +done: + error = vie_update_register(vm, vcpuid, gpr_map[vie->reg], dst, size); + if (error) + return (error); + + /* + * AMD: OF, CF cleared; SF/AF/PF undefined; ZF set by result. + * Intel: ZF is set by result; AF/SF/PF undefined; all others cleared. + */ + rflags &= ~RFLAGS_STATUS_BITS; + if (dst == 0) + rflags |= PSL_Z; + error = vie_update_register(vm, vcpuid, VM_REG_GUEST_RFLAGS, rflags, + 8); + return (error); +} + +static int emulate_add(void *vm, int vcpuid, uint64_t gpa, struct vie *vie, mem_region_read_t memread, mem_region_write_t memwrite, void *arg) { @@ -1744,6 +1826,10 @@ vmm_emulate_instruction(void *vm, int vcpuid, uint64_t break; case VIE_OP_TYPE_TEST: error = emulate_test(vm, vcpuid, gpa, vie, + memread, memwrite, memarg); + break; + case VIE_OP_TYPE_BEXTR: + error = emulate_bextr(vm, vcpuid, gpa, vie, paging, memread, memwrite, memarg); break; default: _______________________________________________ svn-src-all@freebsd.org mailing list https://lists.freebsd.org/mailman/listinfo/svn-src-all To unsubscribe, send any mail to "svn-src-all-unsubscr...@freebsd.org"
