Re: [Xen-devel] [PATCH] AMD/IO-APIC: Use old IO-APIC ack method if AMD 813{1, 2} PCI-X tunnel is present

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

On 04/06/13 10:03, Jan Beulich wrote:
>>>> On 03.06.13 at 22:44, Andrew Cooper <andrew.cooper3@xxxxxxxxxx> wrote:
>> References at time of patch:
>>
>> AMD 8132 PCI-X HyperTransport Tunnel
>> http://support.amd.com/us/ChipsetMotherboard_TechDocs/30801.pdf 
>>
>> AMD 8131 PCI-X HyperTransport Tunnel
>> http://support.amd.com/us/ChipsetMotherboard_TechDocs/26310_AMD-8131_HyperTra
>>  
>> nsport_PCI-X_Tunnel_Revision_Guide_rev_3_18.pdf
>>
>> The IO-APICs on the above two PCI-X HyperTransport Tunnels will issue illegal
>> HT packets if an interrupt gets masked while active.
>>
>> This is sadly exactly what the "new" IO-APIC ack mode does.  The "old" ack
>> mode does however avoid this bad behaviour, and stabilises an affected 
>> system belonging to a customer.
> Ugly.
>
> Can you tell whether any of these systems have more than a single
> IO-APIC? Because if they don't, I'd have a much smaller patch
> (defaulting to "old" on single-IO-APIC systems) that we have been
> carrying for ages, but that wasn't liked by Keir when submitted
> originally.

The system which caused us the issue has 3 IO-APICs.  Two of these
tunnels and a southbridge one.

>
>> --- a/xen/arch/x86/io_apic.c
>> +++ b/xen/arch/x86/io_apic.c
>> @@ -2016,8 +2016,70 @@ static void __init ioapic_pm_state_alloc
>>      BUG_ON(ioapic_pm_state == NULL);
>>  }
>>  
>> +/* AMD 8131 and 8132 PCI-X HyperTransport Tunnel IO-APICs will issue illegal
>> + * HyperTransport packets if an interrupt is masked while active.  This 
>> leads
>> + * to system instability and crashes with no obvious cause.
>> + *
>> + * This is sadly the exact behaviour of the "new" IO-APIC ack mode, but 
>> using
>> + * "old" mode works around the issue.
>> + */
>> +void __init amd813x_errata_quirks(void)
>> +{
>> +    unsigned i, found = 0;
>> +    uint32_t bus, dev, vendor_id;
>> +
>> +    if ( boot_cpu_data.x86_vendor != X86_VENDOR_AMD )
>> +        return;
>> +
>> +    /* Check for the affected IO-APIC version (0x11) to save scanning the 
>> PCI
>> +     * bus on most systems. */
>> +    for ( i = 0; i < nr_ioapics; ++i )
>> +    {
>> +        if ( mp_ioapics[i].mpc_apicver == 0x11 )
>> +        {
>> +            found = 1;
>> +            break;
>> +        }
>> +    }
>> +
>> +    if ( !found )
>> +        return;
>> +
>> +    for ( bus = 0; bus < 256; ++bus )
>> +    {
>> +        for ( dev = 0; dev < 32; ++dev )
>> +        {
>> +            /* IO-APIC is always Function 1.  Check for Multifunction. */
>> +            if ( !( pci_conf_read8(0, bus, dev, 0, PCI_HEADER_TYPE ) & 0x80 
>> ) )
>> +                continue;
>> +
>> +            vendor_id = pci_conf_read32(0, bus, dev, 1, PCI_VENDOR_ID);
>> +
>> +            /* 0x7451 is AMD-8131 PCI-X IO-APIC */
>> +            if ( vendor_id == 0x74511022 )
>> +            {
>> +                printk(XENLOG_WARNING "Found AMD 8131 PCI-X tunnel. "
>> +                       "Forcing IO-APIC ack method to 'old' due to erratum 
>> #63\n");
>> +                ioapic_ack_new = 0;
>> +                return;
>> +            }
>> +            /* 0x7459 is AMD-8132 PCI-X IO-APIC */
>> +            else if ( vendor_id == 0x74591022 )
>> +            {
>> +                printk(XENLOG_WARNING "Found AMD 8132 PCI-X tunnel. "
>> +                       "Forcing IO-APIC ack method to 'old' due to erratum 
>> #81\n");
>> +                ioapic_ack_new = 0;
>> +                return;
>> +            }
>> +
>> +        }
>> +    }
>> +}
>> +
>>  void __init setup_IO_APIC(void)
>>  {
>> +    amd813x_errata_quirks();
>> +
> Just like said on another patch of yours recently - you shouldn't
> override command line options.
>
> Jan
>

OK - I will tweak it a little.

~Andrew

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