Re: [Xen-devel] [BUG] Xen vm kernel crash in get_free_entries.

[Sander Eikelenboom <linux@xxxxxxxxxxxxxx>]

Tuesday, November 26, 2013, 11:00:15 PM, you wrote:


> Tuesday, November 26, 2013, 9:08:47 PM, you wrote:

>> On Wed, Nov 13, 2013 at 09:40:58AM +0000, Ian Campbell wrote:
>>> On Tue, 2013-11-12 at 10:56 -0500, Konrad Rzeszutek Wilk wrote:
>>> > On Thu, Nov 07, 2013 at 01:47:03PM +0000, Ian Campbell wrote:
>>> > > On Thu, 2013-11-07 at 09:20 +0400, Astarta wrote:
>>> > > > Hello,
>>> > > > 
>>> > > > Let me bring some new life to this discussion.
>>> > > > 
>>> > > > I've investigated a bit and found another way to make  kernels 
>>> > > > starting 
>>> > > > from 3.8.x to boot on the VMs with platform device_id 0002.
>>> > > > Reverting of 
>>> > > > xen-grant-table-correctly-initialize-grant-table-version-1 
>>> > > > patch is not necessary.
>>> > > > 
>>> > > > We can simply modify struct pci_device_id platform_pci_tbl[] (in 
>>> > > > drivers/xen/platform-pci.c) to respect 0002 and 0000 device ids.
>>> > > > That makes the kernel (3.8.x and 3.11.6) to boot correctly, disks and 
>>> > > > network are also recognized.
>>> > > 
>>> > > I think this is just working around the problem, by avoiding the
>>> > > situation where the error occurs. You could just as well switch to
>>> > > platform device id < 2.
>>> > 
>>> > I am bit late to this discussion - but shouldn't there be something
>>> > in the kernel to deal with this?
>>> 
>>> Well, ideally the kernel wouldn't crash ;-)

>> This patch should solve that (untested, but at least compile tested):
>> Please test it.

> Hi Konrad,

> I just gave it a shot on qemu-xen-traditional (since support for 
> xen_platform_pci=0 is not upstream (yet))
> It doesn't crash anymore on boot, but the guest now doesn't have any disks, 
> so it ends in busybox because it can't find a root partition.
> I would have expected it to be using qemu emulated disks now, but a "cat 
> /proc/partitions" in busybox shows nothing.
> But that's perhaps qemu code ejecting the emulated disks anyhow ...

Hi Konrad,

With the linux PATA modules compiled in it now also boots fine with 
qemu-xen-traditional and xen_platform_pci=0

Thanks,

Sander

> In the config file i use:
>  disk = [ 'phy:/dev/xen_vms/testvm,hda,w' ]

> --
> Sander

>> From f7d3581aa19a35ea3ff10b965b2b08843e923635 Mon Sep 17 00:00:00 2001
>> From: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
>> Date: Tue, 26 Nov 2013 15:05:40 -0500
>> Subject: [PATCH] xen/pvhvm: If xen_platform_pci=0 is set don't blow up.

>> *TODO*

>> Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
>> ---
>>  drivers/block/xen-blkfront.c               |  2 +-
>>  drivers/input/misc/xen-kbdfront.c          |  4 ++++
>>  drivers/net/xen-netfront.c                 |  2 +-
>>  drivers/xen/xenbus/xenbus_probe_frontend.c |  2 +-
>>  include/xen/platform_pci.h                 | 13 +++++++++++++
>>  5 files changed, 20 insertions(+), 3 deletions(-)

>> diff --git a/drivers/block/xen-blkfront.c b/drivers/block/xen-blkfront.c
>> index 432db1b..bcbaf0b 100644
>> --- a/drivers/block/xen-blkfront.c
>> +++ b/drivers/block/xen-blkfront.c
>> @@ -2074,7 +2074,7 @@ static int __init xlblk_init(void)
>>         if (!xen_domain())
>>                 return -ENODEV;
>>  
>> -       if (xen_hvm_domain() && !xen_platform_pci_unplug)
>> +       if (xen_err_out())
>>                 return -ENODEV;
>>  
>>         if (register_blkdev(XENVBD_MAJOR, DEV_NAME)) {
>> diff --git a/drivers/input/misc/xen-kbdfront.c 
>> b/drivers/input/misc/xen-kbdfront.c
>> index e21c181..9d250cf 100644
>> --- a/drivers/input/misc/xen-kbdfront.c
>> +++ b/drivers/input/misc/xen-kbdfront.c
>> @@ -29,6 +29,7 @@
>>  #include <xen/interface/io/fbif.h>
>>  #include <xen/interface/io/kbdif.h>
>>  #include <xen/xenbus.h>
>> +#include <xen/platform_pci.h>
>>  
>>  struct xenkbd_info {
>>         struct input_dev *kbd;
>> @@ -380,6 +381,9 @@ static int __init xenkbd_init(void)
>>         if (xen_initial_domain())
>>                 return -ENODEV;
>>  
>> +       if (xen_err_out())
>> +               return -ENODEV;
>> +
>>         return xenbus_register_frontend(&xenkbd_driver);
>>  }
>>  
>> diff --git a/drivers/net/xen-netfront.c b/drivers/net/xen-netfront.c
>> index e59acb1..be2744b 100644
>> --- a/drivers/net/xen-netfront.c
>> +++ b/drivers/net/xen-netfront.c
>> @@ -2115,7 +2115,7 @@ static int __init netif_init(void)
>>         if (!xen_domain())
>>                 return -ENODEV;
>>  
>> -       if (xen_hvm_domain() && !xen_platform_pci_unplug)
>> +       if (xen_err_out())
>>                 return -ENODEV;
>>  
>>         pr_info("Initialising Xen virtual ethernet driver\n");
>> diff --git a/drivers/xen/xenbus/xenbus_probe_frontend.c 
>> b/drivers/xen/xenbus/xenbus_probe_frontend.c
>> index 129bf84..b1c0f2a 100644
>> --- a/drivers/xen/xenbus/xenbus_probe_frontend.c
>> +++ b/drivers/xen/xenbus/xenbus_probe_frontend.c
>> @@ -496,7 +496,7 @@ subsys_initcall(xenbus_probe_frontend_init);
>>  #ifndef MODULE
>>  static int __init boot_wait_for_devices(void)
>>  {
>> -       if (xen_hvm_domain() && !xen_platform_pci_unplug)
>> +       if (xen_err_out())
>>                 return -ENODEV;
>>  
>>         ready_to_wait_for_devices = 1;
>> diff --git a/include/xen/platform_pci.h b/include/xen/platform_pci.h
>> index 438c256..a5bbd0b 100644
>> --- a/include/xen/platform_pci.h
>> +++ b/include/xen/platform_pci.h
>> @@ -47,5 +47,18 @@ static inline int xen_must_unplug_disks(void) {
>>  }
>>  
>>  extern int xen_platform_pci_unplug;
>> +static  bool xen_err_out(void)
>> +{
>>  
>> +       if (!xen_domain())
>> +               return true;
>> +
>> +       if (xen_hvm_domain()) {
>> +               if (xen_platform_pci_unplug & (XEN_UNPLUG_UNNECESSARY | 
>> XEN_UNPLUG_NEVER))
>> +                       return true;
>> +               if (xen_platform_pci_unplug == 0)
>> +                       return true;
>> +       }
>> +       return false;
>> +}
>>  #endif /* _XEN_PLATFORM_PCI_H */





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