RE: [Xen-devel] iommu support on AMD64

["Nakajima, Jun" <jun.nakajima@xxxxxxxxx>]

Langsdorf, Mark wrote:
>> Langsdorf, Mark wrote:
>>> I'm working on getting IOMMU support enabled
>>> for AMD64 in Xen.
>>> 
>>> The current aperture.c code in dom0 requires
>>> several calls to read_pci_config() to find
>>> the AMD northbridge.  These calls are causing
>>> my system to crash.
>> 
>> Can you be more specific (output from serial connection, for
>> example)? The outl instruction causes #GP, and the emulator
>> in Xen handle it. So, it's possible the emulator has a bug?
> 
> The serial console is pretty broken on AMD64.  I was
> hoping to not have to debug the serial console in
> order to fix the IOMMU problem.
> 
> Here's the last page or two of messages on my screen:
> (all lines prefixed with (XEN))  I hand copied it but
> all the values are correct.
> 
> *** LOADING DOMAIN 0 ***
> Xen-ELF header found:
>
'GUEST_OS=linux,GUEST_VER=2.6,XEN_VER=3.0,VIRT_BASE=0xffffffff80000000,L
> OADER=generic'
> PHYSICAL MEMORY ARRANGEMENT:
>  Dom0 alloc.: 0000000007000000->0000000008000000 (258048 pages to be
> allocated)

I see you assigned just 1GB memory for dom0? 

> VIRTUAL MEMORY ARRANGEMNET:
>  Loaded kernel: ffffffff80100000->ffffffff8063e086
>  Init. ramdisk: ffffffff8063f000->ffffffff8063f000
>  Phys-Mach map: ffffffff8063f000->ffffffff8063f000
>  Start info:    ffffffff8063f000->ffffffff80840000
>  Page tables:   ffffffff80840000->ffffffff80849000
>  Boot stack:    ffffffff80849000->ffffffff8084a000
>  TOTAL:         ffffffff80000000->ffffffff80c00000
>  ENTRY ADDRESS: ffffffff80100000
> Scrubbing Free RAM: .................................done.

Looks like you are getting the failure at very early initialization
stage. In this case, I think it's better to add prink in Xen, for
example, in emulate_privileged_op(struct cpu_user_regs *regs) to check
it's failing or not.


> *** Serial input -> DOM0 (type 'CTRL-a' three times to switch input to
> Xen).
> Domain 0 (vcpu#0) crashed on cpu#0:
> CPU:  0
> RIP:  e033:[<fffffff80600cc2>]
> RFLAGS:       000000000000286   CONTEXT: guest
> rax: 000000008000c300 rbx: 000000000000c000   rcx: 0000000000007fff
> rdx: 0000000000000cf8 rsi: 00000000000007e5   rdi: ffffffff804d2be0
> rbp: 0000000000000018 rsp: ffffffff805f5ea0   r8:  000000o000000034
> r9:  0000000000000000 r10: 00000000ffffffff   r11: 0000000o00000000
> r12: 0000000000000cf8 r13: 0000000000000cfc   r14: 00000000o00d2000
> r15: ffffffff804ca200 cr0: 000000008005003b   cr3: 0000000007101000
> Guest stack trace from rsp=ffffffff805f5ea0:
>   (guest stack omitted because it's basically the above registers)
> Domain 0 shutdown: rebooting machine.
> 
> Is there a way to turn on more debug information inside the hypervisor
> itself?
> 
> -Mark Langsdorf
> AMD, Inc.


Jun
---
Intel Open Source Technology Center

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