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


  • To: "Keir Fraser" <keir@xxxxxxxxxxxxx>
  • From: "Brady Chen" <chenchp@xxxxxxxxx>
  • Date: Wed, 8 Aug 2007 00:06:28 +0800
  • Cc: tygrawy@xxxxxxxxx, xen-devel@xxxxxxxxxxxxxxxxxxx, Z24 <z24@xxxxxxx>, AL.LINUX@xxxxxxxxxxx
  • Delivery-date: Tue, 07 Aug 2007 09:03:58 -0700
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  • List-id: Xen developer discussion <xen-devel.lists.xensource.com>

Yes, the printfs are the only changes. once I remove these prints, the
trap comes back, with the same EIP (D0800)

I tried to keep the first two printfs, the trap comes with different EIP(D19FD)
static unsigned
address(struct regs *regs, unsigned seg, unsigned off)
{
        uint64_t gdt_phys_base;
        unsigned long long entry;
        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;
                else
                        panic("segment is zero, but not in real mode!\n");
        }

        printf("f 2\n");

xen dmesg output:
(XEN) HVM3: 0x0000D71F: 0xD00:0x071F (0) opc 0x83
(XEN) HVM3: f 1
(XEN) HVM3: f 2
(XEN) HVM3: 0x0000D71F: 0xD00:0x071F (0) external interrupt 8
(XEN) HVM3: f 1
(XEN) HVM3: f 1
(XEN) HVM3: f 1
(XEN) HVM3: Trap (0x6) while in real mode
(XEN) HVM3: eax        CFAE ecx           0 edx           0 ebx       D75B4
(XEN) HVM3: esp       D7564 ebp       D75A0 esi         71F edi           8
(XEN) HVM3: trapno        6 errno         0
(XEN) HVM3: eip       D19FD cs           10 eflags    13046
(XEN) HVM3: uesp       CFAE uss           0
(XEN) HVM3: ves       D4C44 vds           8 vfs          83 vgs         71F
(XEN) HVM3: cr0       50032 cr2           0 cr3           0 cr4         651
(XEN) HVM3:
(XEN) HVM3: Halt called from %eip 0xD037C


and the objdump shows that:
000d1970 <interrupt>:
   d1970:       55                      push   %ebp
   d1971:       89 e5                   mov    %esp,%ebp
   d1973:       57                      push   %edi
   d1974:       89 d7                   mov    %edx,%edi
   d1976:       56                      push   %esi
  ....
   d19f8:       66 89 30                mov    %si,(%eax)
   d19fb:       31 d2                   xor    %edx,%edx
   d19fd:       8d 34 bd 00 00 00 00    lea    0x0(,%edi,4),%esi
   d1a04:       81 63 30 ff fd ff ff    andl   $0xfffffdff,0x30(%ebx)
   d1a0b:       89 d8                   mov    %ebx,%eax
   d1a0d:       89 34 24                mov    %esi,(%esp)


On 8/7/07, Keir Fraser <keir@xxxxxxxxxxxxx> wrote:
> 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@xxxxxxxxx> 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@xxxxxxxxx> 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@xxxxxxxxxxxxx> 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@xxxxxxxxx> 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@xxxxxxxxxxxxx> wrote:
> >>>>> On 7/8/07 10:29, "Keir Fraser" <keir@xxxxxxxxxxxxx> 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@xxxxxxxxxxxxxxxxxxx
> >>>> http://lists.xensource.com/xen-devel
> >>>
> >>>
> >>
> >
> > _______________________________________________
> > Xen-devel mailing list
> > Xen-devel@xxxxxxxxxxxxxxxxxxx
> > http://lists.xensource.com/xen-devel
>
>

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