RE: [Xen-devel] Re: Oops when loading xen_platform_pci module in HVMdomain on CS 11429

["Yu, Ke" <ke.yu@xxxxxxxxx>]

Steve Dobbelstein wrote:
> steved@xxxxxxxxxx wrote on 09/05/2006 07:56:00 PM:
> 
> Digging into this further I found that the problem is that they
> hypercall mechanism its trying to execute the instructions for the
> hypercall which reside in the hypercall stubs page.  However, the
> page table entry for the page has the _PAGE_NX (no execute) bit set. 
> (I'm running a 64-bit OS with PAE in the HVM domain.)  The error code
> in the oops (0x11) indicates that the page fault is because of the
> _PAGE_NX bit.  0x01 -> access rights violation  0x10 -> The fault was
> caused by an instruction fetch. 
> 
> I tried hacking some code to turn off the NX bit in the PTE for the
> hypercall stubs page, but I still get the oops.  I'm thinking it's
> because the NX bit is set in the PMD.
> 
> I'm quite new to the paging mechanism, so I'm not sure how to fix
> this at the moment.   I'll keep poking around.  thought I'd share my
> findings so far.
> 
> Steve D.
> 

I also meet this opps in IA32 Non-PAE guest . Since it has no NX bit in IA32, 
there may be other issue. Hope this info is helpful.

Best Regards
Ke

Xen version 3.0.
Hypercall area is 1 pages (order 0 allocation)
Unable to handle kernel paging request at virtual address 1dd9c27c
 printing eip:
cdd9e00c
*pde = 00000000
Oops: 0002 [#1]
PREEMPT 
Modules linked in: xen_platform_pci
CPU:    0
EIP:    0060:[<cdd9e00c>]    Not tainted VLI
EFLAGS: 00010202   (2.6.16 #3) 
EIP is at 0xcdd9e00c
eax: 1dd9c27c   ebx: 00000006   ecx: cdcffe04   edx: 00000000
esi: 00000001   edi: cdcffe08   ebp: 00000006   esp: cdcffdf4
ds: 007b   es: 007b   ss: 0068
Process insmod (pid: 3778, threadinfo=cdcfe000 task=cfc16530)
Stack: <0>0000007b d0809f53 d080a7af cdd9c000 00000000 00000000 00000000 
00000007 
       00000000 f3000000 0000c100 d081100e 566e6558 65584d4d 4d4d566e cfeb0900 
       cfeb0800 cfeb0800 f3000000 cfeb0800 d0809667 c0454b00 0000c100 00000100 
Call Trace:
 [<d0809f53>] setup_xen_features+0x43/0x90 [xen_platform_pci]
 [<d081100e>] init_xen_info+0xe/0xa0 [xen_platform_pci]
 [<d0809667>] platform_pci_init+0xf7/0x250 [xen_platform_pci]
 [<c012a900>] __call_usermodehelper+0x0/0x70
 [<c022caea>] pci_match_device+0x2a/0x120
 [<c022cc65>] __pci_device_probe+0x65/0x80
 [<c022ccaf>] pci_device_probe+0x2f/0x60
 [<c02940e9>] driver_probe_device+0x99/0xf0
 [<c02941c0>] __driver_attach+0x0/0x70
 [<c0294227>] __driver_attach+0x67/0x70
 [<c029347d>] bus_for_each_dev+0x5d/0x80
 [<c0294255>] driver_attach+0x25/0x30
 [<c02941c0>] __driver_attach+0x0/0x70
 [<c0293a84>] bus_add_driver+0x84/0xe0
 [<c0294783>] driver_register+0x63/0xa0
 [<c0294700>] klist_devices_get+0x0/0x10
 [<c0294710>] klist_devices_put+0x0/0x10
 [<c022cf65>] __pci_register_driver+0x55/0x90
 [<d08110b9>] platform_pci_module_init+0x19/0x50 [xen_platform_pci]
 [<c0136cc2>] sys_init_module+0x132/0x200
 [<c0103115>] syscall_call+0x7/0xb
Code: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 
00 00 00 00 00 00 00 f8 04 14 46 05 00 00 00 50 06 14 46 <00> 00 00 00 50 06 14 
46 00 00 00 00 00 00 00 00 00 00 00 00 00

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