Re: Re: [Xen-users] boot a existing windows in hvm domain

[Keir Fraser <keir@xensource.com>]

Very weird. The emulations now aren't at the same address as before either
(0xd4c3 rather than 0xd71b). Is the *only* difference that you added these
printf()s -- is it at all possible that the guest is executing down a
different path here for other reasons? If it's really down to the printf()s
then I guess you'll have to shuffle/remove printf()s to get the old
behaviour back.

 -- Keir

On 7/8/07 12:35, "Brady Chen" <chenchp@gmail.com> wrote:

> it's strange:
> if i add these prints, i get " Unknown opcode", not "trap".
> ===added printf
> [root@localhost firmware]# hg diff -p  vmxassist/vm86.c
> diff -r 6f18f5bdeea3 tools/firmware/vmxassist/vm86.c
> --- a/tools/firmware/vmxassist/vm86.c   Mon Aug 06 15:33:42 2007 +0100
> +++ b/tools/firmware/vmxassist/vm86.c   Tue Aug 07 19:33:55 2007 +0800
> @@ -40,7 +40,7 @@ static struct regs saved_rm_regs;
>  static struct regs saved_rm_regs;
> 
>  #ifdef DEBUG
> -int traceset = 0;
> +int traceset = ~0;
> 
>  char *states[] = {
>         "<VM86_REAL>",
> @@ -128,6 +128,7 @@ address(struct regs *regs, unsigned seg,
>         unsigned seg_base, seg_limit;
>         unsigned entry_low, entry_high;
> 
> +       printf("f 1\n");
>         if (seg == 0) {
>                 if (mode == VM86_REAL || mode == VM86_REAL_TO_PROTECTED)
>                         return off;
> @@ -135,12 +136,16 @@ address(struct regs *regs, unsigned seg,
>                         panic("segment is zero, but not in real mode!\n");
>         }
> 
> +       printf("f 2\n");
>         if (mode == VM86_REAL || seg > oldctx.gdtr_limit ||
>                 (mode == VM86_REAL_TO_PROTECTED && regs->cs == seg))
>                 return ((seg & 0xFFFF) << 4) + off;
> 
> +       printf("f 3\n");
>         gdt_phys_base = guest_linear_to_phys(oldctx.gdtr_base);
> +       printf("f 4\n");
>         if (gdt_phys_base != (uint32_t)gdt_phys_base) {
> +               printf("f 5\n");
>                 printf("gdt base address above 4G\n");
>                 cpuid_addr_value(gdt_phys_base + 8 * (seg >> 3), &entry);
>         } else
> @@ -152,14 +157,17 @@ address(struct regs *regs, unsigned seg,
>         seg_base  = (entry_high & 0xFF000000) | ((entry >> 16) & 0xFFFFFF);
>         seg_limit = (entry_high & 0xF0000) | (entry_low & 0xFFFF);
> 
> +       printf("f 6\n");
>         if (entry_high & 0x8000 &&
>                 ((entry_high & 0x800000 && off >> 12 <= seg_limit) ||
>                 (!(entry_high & 0x800000) && off <= seg_limit)))
>                 return seg_base + off;
> +       printf("f 7\n");
> 
>         panic("should never reach here in function address():\n\t"
>                   "entry=0x%08x%08x, mode=%d, seg=0x%08x, offset=0x%08x\n",
>                   entry_high, entry_low, mode, seg, off);
> +       printf("f 8\n");
> 
>         return 0;
>  }
> @@ -286,6 +294,7 @@ fetch8(struct regs *regs)
>         unsigned addr = address(regs, regs->cs, MASK16(regs->eip));
> 
>         regs->eip++;
> +       printf("f 9\n");
>         return read8(addr);
>  }
> 
> ===output when add many printf
> (XEN) HVM12: 0x0000D4C3: 0xD00:0x04C3 (0) addr32addr32f 1
> (XEN) HVM12: f 2
> (XEN) HVM12: f 9
> (XEN) HVM12: f 1
> (XEN) HVM12: f 2
> (XEN) HVM12: 0x0000D4C3: 0xD00:0x04C3 (0) data32data32f 1
> (XEN) HVM12: f 2
> (XEN) HVM12: f 9
> (XEN) HVM12: f 1
> (XEN) HVM12: f 2
> (XEN) HVM12: 0x0000D4C3: 0xD00:0x04C3 (0) opc 0x83opc 0xD7704f 1
> (XEN) HVM12: f 2
> (XEN) HVM12: Unknown opcode at 0D00:04C3=0xD4C3
> (XEN) HVM12: Halt called from %eip 0xD3B4A
> 
> On 8/7/07, Brady Chen <chenchp@gmail.com> wrote:
>> Hi, yes, it's crashed in fetch8. it's very slow after I add this print info.
>> the main function of fetch8 seems to be address(). seems crashed in
>> address().
>> 
>> (XEN) HVM7: after write16 of movw
>> (XEN) HVM7: top of opcode
>> (XEN) HVM7: Before fetch8
>> (XEN) HVM7: eax        7E80 ecx        2D1B edx           0 ebx        404E
>> (XEN) HVM7: esp       D76F4 ebp        1FF0 esi         7BE edi       C37FE
>> (XEN) HVM7: trapno        D errno         0
>> (XEN) HVM7: eip         71F cs          D00 eflags    33206
>> (XEN) HVM7: uesp       CFB4 uss           0
>> (XEN) HVM7: ves         D00 vds         D00 vfs           0 vgs           0
>> (XEN) HVM7: cr0       50032 cr2           0 cr3           0 cr4         651
>> (XEN) HVM7:
>> (XEN) HVM7: Trap (0x6) while in real mode
>> (XEN) HVM7: eax         D00 ecx           0 edx         71F ebx          89
>> (XEN) HVM7: esp       D75E4 ebp       D7630 esi       D7620 edi         D00
>> (XEN) HVM7: trapno        6 errno         0
>> (XEN) HVM7: eip       D0800 cs           10 eflags    13046
>> (XEN) HVM7: uesp        71F uss       D76D4
>> (XEN) HVM7: ves       D7610 vds       D3AB9 vfs       D762C vgs       D7644
>> (XEN) HVM7: cr0       50032 cr2           0 cr3           0 cr4         651
>> (XEN) HVM7:
>> (XEN) HVM7: 0xd0800 is 0xFFFF
>> (XEN) HVM7: 0xd0804 is 0x7D8B
>> (XEN) HVM7: Halt called from %eip 0xD037C
>> 
>> 
>> On 8/7/07, Keir Fraser <keir@xensource.com> wrote:
>>> How about trying:
>>>  printf("Before fetch8\n");
>>>  dump_regs(regs);
>>>  opc = fetch8(regs);
>>>  printf("After fetch8\n");
>>>  switch (opc) { ...
>>> 
>>> This will let you see what eip is being fetched from, and also confirm that
>>> the crash happens within fetch8().
>>> 
>>> You could also try adding more printf()s inside fetch8() and address() to
>>> find out which specific bit of fetch8() is crashing (if that indeed the
>>> function that is crashing).
>>> 
>>>  -- Keir
>>> 
>>> On 7/8/07 11:30, "Brady Chen" <chenchp@gmail.com> wrote:
>>> 
>>>> Hi, Keir,
>>>> I made the change as you said:
>>>> change diff is:
>>>> [root@localhost firmware]# hg diff vmxassist/vm86.c
>>>> diff -r 6f18f5bdeea3 tools/firmware/vmxassist/vm86.c
>>>> --- a/tools/firmware/vmxassist/vm86.c   Mon Aug 06 15:33:42 2007 +0100
>>>> +++ b/tools/firmware/vmxassist/vm86.c   Tue Aug 07 18:26:12 2007 +0800
>>>> @@ -40,7 +40,7 @@ static struct regs saved_rm_regs;
>>>>  static struct regs saved_rm_regs;
>>>> 
>>>>  #ifdef DEBUG
>>>> -int traceset = 0;
>>>> +int traceset = ~0;
>>>> 
>>>>  char *states[] = {
>>>>         "<VM86_REAL>",
>>>> @@ -620,6 +620,7 @@ movr(struct regs *regs, unsigned prefix,
>>>>                         TRACE((regs, regs->eip - eip,
>>>>                                 "movw %%%s, *0x%x", rnames[r], addr));
>>>>                         write16(addr, MASK16(val));
>>>> +                       printf("after write16 of movw\n");
>>>>                 }
>>>>                 return 1;
>>>> 
>>>> @@ -1305,6 +1306,7 @@ opcode(struct regs *regs)
>>>>         unsigned eip = regs->eip;
>>>>         unsigned opc, modrm, disp;
>>>>         unsigned prefix = 0;
>>>> +       printf("top of opcode\n");
>>>> 
>>>>         if (mode == VM86_PROTECTED_TO_REAL &&
>>>>                 oldctx.cs_arbytes.fields.default_ops_size) {
>>>> @@ -1712,6 +1714,8 @@ trap(int trapno, int errno, struct regs
>>>>                 if (trapno == 14)
>>>>                         printf("Page fault address 0x%x\n", get_cr2());
>>>>                 dump_regs(regs);
>>>> +               printf("0xd0800 is 0x%0x\n", *((unsigned short*)0xd0800));
>>>> +               printf("0xd0804 is 0x%0x\n", *((unsigned short*)0xd0804));
>>>>                 halt();
>>>>         }
>>>>  }
>>>> 
>>>> 
>>>> here is the output:
>>>> (XEN) HVM6: top of opcode
>>>> (XEN) HVM6: 0x0000D71F: 0xD00:0x071F (0) data32
>>>> (XEN) HVM6: 0x0000D71F: 0xD00:0x071F (0) opc 0x83
>>>> (XEN) HVM6: top of opcode
>>>> (XEN) HVM6: 0x0000D71B: 0xD00:0x071B (0) %es:
>>>> (XEN) HVM6: 0x0000D71B: 0xD00:0x071B (0) addr32
>>>> (XEN) HVM6: 0x0000D71D: 0xD00:0x071D (0) movw %ax, *0xD07FE
>>>> (XEN) HVM6: after write16 of movw
>>>> (XEN) HVM6: top of opcode
>>>> (XEN) HVM6: Trap (0x6) while in real mode
>>>> (XEN) HVM6: eax         D00 ecx           0 edx         71F ebx         71E
>>>> (XEN) HVM6: esp       D7554 ebp       D75A0 esi       D7590 edi         D00
>>>> (XEN) HVM6: trapno        6 errno         0
>>>> (XEN) HVM6: eip       D0800 cs           10 eflags    13046
>>>> (XEN) HVM6: uesp      D4C29 uss           2
>>>> (XEN) HVM6: ves       D4C18 vds       D4D9C vfs       D07FE vgs       D75B4
>>>> (XEN) HVM6: cr0       50032 cr2           0 cr3           0 cr4         651
>>>> (XEN) HVM6:
>>>> (XEN) HVM6: 0xd0800 is 0xFFFF
>>>> (XEN) HVM6: 0xd0804 is 0x7D8B
>>>> (XEN) HVM6: Halt called from %eip 0xD037C
>>>> 
>>>> objdump:
>>>>    d07ef:       e9 2f ff ff ff          jmp    d0723 <address+0x23>
>>>>    d07f4:       8b 55 08                mov    0x8(%ebp),%edx
>>>>    d07f7:       89 f8                   mov    %edi,%eax
>>>>    d07f9:       8b 5d f4                mov    0xfffffff4(%ebp),%ebx
>>>>    d07fc:       8b 75 f8                mov    0xfffffff8(%ebp),%esi
>>>>    d07ff:       25 ff ff 00 00          and    $0xffff,%eax
>>>>    d0804:       8b 7d fc                mov    0xfffffffc(%ebp),%edi
>>>>    d0807:       89 ec                   mov    %ebp,%esp
>>>>    d0809:       c1 e0 04                shl    $0x4,%eax
>>>>    d080c:       01 d0                   add    %edx,%eax
>>>>    d080e:       5d                      pop    %ebp
>>>> 
>>>> seems the memory is correct, it's crashed in opcode()
>>>> and i think it's fetch8(regs) which crash the system. I tried
>>>> fetch8(regs) in trap(), but it cause more traps, and let the hvm guest
>>>> be reset.
>>>> 
>>>> On 8/7/07, Keir Fraser <keir@xensource.com> wrote:
>>>>> On 7/8/07 10:29, "Keir Fraser" <keir@xensource.com> wrote:
>>>>> 
>>>>>> What would be useful is to try to add tracing to see how far vmxassist
>>>>>> gets
>>>>>> after its last line of tracing before the trap occurs. That last line is
>>>>>> currently from vm86.c, line 620. You might try adding extra printf()
>>>>>> statements imemdiately after the write16() on line 622, and also at the
>>>>>> top
>>>>>> of the opcode() function. We need to find out at what point vmxassist is
>>>>>> jumping to this bogus address d0800.
>>>>> 
>>>>> Oh, another possibility is that vmxassist has been corrupted in memory.
>>>>> This
>>>>> is particularly likely because, according to the objdump, the
>>>>> 'instruction'
>>>>> that starts at d0800 is actually valid (it'd be an ADD of some sort).
>>>>> 
>>>>> So, within trap() you might want to read say 16 bytes starting at 0xd0800
>>>>> and printf() them. So we can see if they match what objdump says should be
>>>>> there.
>>>>> 
>>>>>  -- Keir
>>>>> 
>>>>> 
>>>> 
>>>> _______________________________________________
>>>> Xen-devel mailing list
>>>> Xen-devel@lists.xensource.com
>>>> http://lists.xensource.com/xen-devel
>>> 
>>> 
>> 
> 
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