From mboxrd@z Thu Jan  1 00:00:00 1970
From: "Chen, Tiejun" <tiejun.chen@intel.com>
Subject: Re: [v7][PATCH 06/16] hvmloader/pci: skip reserved
	ranges
Date: Wed, 15 Jul 2015 18:34:55 +0800
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To: Jan Beulich <JBeulich@suse.com>, Andrew Cooper <andrew.cooper3@citrix.com>, Ian Campbell <ian.campbell@citrix.com>, Wei Liu <wei.liu2@citrix.com>, Ian Jackson <ian.jackson@eu.citrix.com>, Stefano Stabellini <stefano.stabellini@eu.citrix.com>, Keir Fraser <keir@xen.org>
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>>> Yet more special casing code you want to add. I said no to this
>>> model, and unless you can address the issue _without_ adding
>>> a lot of special casing code, the answer will remain no (subject
>>
>> What about this?
>>
>> @@ -301,6 +301,19 @@ void pci_setup(void)
>>                pci_mem_start <<= 1;
>>        }
>>
>> +    for ( i = 0; i < memory_map.nr_map ; i++ )
>> +    {
>> +        uint64_t reserved_start, reserved_size;
>> +        reserved_start = memory_map.map[i].addr;
>> +        reserved_size = memory_map.map[i].size;
>> +        if ( check_overlap(pci_mem_start, pci_mem_end - pci_mem_start,
>> +                           reserved_start, reserved_size) )
>> +        {
>> +            printf("Reserved device memory conflicts current PCI memory.\n");
>> +            BUG();
>> +        }
>> +    }
>
> So what would the cure be if someone ran into this BUG() (other
> than removing the device associated with the conflicting RMRR)?

Maybe I  can move this chunk of codes downward those actual allocation 
to check if RDM conflicts with the final allocation, and then just 
disable those associated devices by writing PCI_COMMAND without BUG() 
like this draft code,

     /* If pci bars conflict with RDM we need to disable this pci device. */
     for ( devfn = 0; devfn < 256; devfn++ )
     {
         bar_sz = pci_readl(devfn, bar_reg);
         bar_data = pci_readl(devfn, bar_reg);
         bar_data_upper = pci_readl(devfn, bar_reg + 4);
         /* Until here we don't conflict high memory. */
         if ( bar_data_upper )
             continue;

         for ( i = 0; i < memory_map.nr_map ; i++ )
         {
             uint64_t reserved_start, reserved_size;
             reserved_start = memory_map.map[i].addr;
             reserved_size = memory_map.map[i].size;
             if ( check_overlap(bar_data & ~(bar_sz - 1), bar_sz,
                                reserved_start, reserved_size) )
             {
                 printf("Reserved device memory conflicts with this pci 
bar,"
                        " so just disable this device.\n");
                 /* Now disable this device */
                 cmd = pci_readw(devfn, PCI_COMMAND);
                 pci_writew(devfn, PCI_COMMAND, ~cmd);
             }
         }
     }

If this is still not fine to you, look I have to raise a request to 
co-maintainers since its hard to step next in practice.

Hi all guys, what about your idea?

Thanks
Tiejun