Aurelien Jarno wrote: > Avi Kivity a écrit : > >> Aurelien Jarno wrote: >> >>> The patch below removes the check for c->modrm_reg == 7 to detect the >>> invlpg instruction, as it was the case before before commit >>> aa38840d3d2e0a804e628077df8d8879b496d741. This fixes the boot of FreeBSD >>> on an AMD64 CPU. >>> >>> It also moves the assignation of c->src.bytes after the test as it is >>> not needed for the invlpg instruction. >>> >>> Signed-off-by: Aurelien Jarno <[EMAIL PROTECTED]> >>> >>> diff --git a/drivers/kvm/x86_emulate.c b/drivers/kvm/x86_emulate.c >>> index fa33fcd..01aa952 100644 >>> --- a/drivers/kvm/x86_emulate.c >>> +++ b/drivers/kvm/x86_emulate.c >>> @@ -824,12 +824,10 @@ modrm_done: >>> c->src.bytes = 4; >>> goto srcmem_common; >>> case SrcMem: >>> - c->src.bytes = (c->d & ByteOp) ? 1 : >>> - c->op_bytes; >>> /* Don't fetch the address for invlpg: it could be unmapped. */ >>> - if (c->twobyte && c->b == 0x01 >>> - && c->modrm_reg == 7) >>> + if (c->twobyte && c->b == 0x01) >>> break; >>> + c->src.bytes = (c->d & ByteOp) ? 1 : c->op_bytes; >>> >>> >>> >> I don't understand why this helps. All of the other instructions in >> this group either have modrm_mod == 3 or do require evaluation of the >> > ^^^^^^^^^ > The test actually concerns modrm_reg and not modrm_mod. Maybe it is wrong? > >
I meant, the instructions all require modrm_mod == 3 which means they reference registers, and not memory. >> source. invlpg is the only one that doesn't. >> > > I have marked the invlpg instruction the same way as it is done in > kvm-37 to know what happens. I get either modrm_reg = 4 or = 6 when the > invlpg instruction is executed, but never = 7. > > Then it isn't the invlpg instruction at all. Rather smsw (modrm_reg == 4) or lmsw ( == 6). I'm confused. (looks) Okay. What we have here is total breakage when emulating an instruction that uses a mod r/m encoding that actually refers to a register (modrm_mod == 3). In x86_decode_insn() we set src.type as OP_MEM, and in x86_emulate_insn() we happily fetch it even though it's a register, generating a fault. It usually doesn't bite us because these instructions are directly executed. The fix is probably to switch to OP_REG if SrcMem and ModRM and modrm_mod == 3 (similarly for DstMem). -- error compiling committee.c: too many arguments to function ------------------------------------------------------------------------- This SF.net email is sponsored by: Splunk Inc. Still grepping through log files to find problems? Stop. Now Search log events and configuration files using AJAX and a browser. Download your FREE copy of Splunk now >> http://get.splunk.com/ _______________________________________________ kvm-devel mailing list kvm-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/kvm-devel
