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

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> 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.

> --- 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


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