Re: [Xen-devel] [xen-unstable] Commit 2ca9fbd739b8a72b16dd790d0fff7b75f5488fb8 AMD IOMMU: allocate IRTE entries instead of using a static mapping, makes dom0 boot process stall several times.

[Sander Eikelenboom <linux@xxxxxxxxxxxxxx>]

Friday, August 23, 2013, 5:21:26 PM, you wrote:

>>>> On 23.08.13 at 17:11, "Jan Beulich" <JBeulich@xxxxxxxx> wrote:
>>>>> On 23.08.13 at 17:05, Sander Eikelenboom <linux@xxxxxxxxxxxxxx> wrote:
>> 
>>> Friday, August 23, 2013, 4:28:43 PM, you wrote:
>>> 
>>>>>>> On 23.08.13 at 00:51, Sander Eikelenboom <linux@xxxxxxxxxxxxxx> wrote:
>>>>> After i got things working on baremetal Linux, i adjusted Xen and 
>>>>> hardcoded 
>>>>> it to add a mapping for ioapic[6]=00:14.0.
>>>>> (the entries for ivrs_ioapic[7] and hpet[0] are actually correct in the 
>>>>> bios 
>> 
>>> 
>>>>> tables, so they don't need correction for me at the moment)
>>> 
>>>> Are you sure about the HPET part of this? I ask because that being
>>>> wrong could be an explanation for the stalls you see when using
>>>> cpuidle (as that could mean those HPET interrupts needed for
>>>> waking CPUs don't arrive).
>>> 
>>>> Speaking of which - why don't you try whether when not using
>>>> FSB-capable HPET channels, the stalls go away? All you'd need
>>>> to change is hpet_fsb_cap_lookup() - it ought to return without
>>>> doing anything (i.e., if you look at the code, as if
>>>> acpi_gbl_FADT.boot_flags had ACPI_FADT_NO_MSI set).
>>> 
>>> Ok adding:
>>> 
>>> @@ -392,6 +392,9 @@ static void __init hpet_fsb_cap_lookup(void)
>>>      u32 id;
>>>      unsigned int i, num_chs;
>>> 
>>> +    printk(XENLOG_INFO "SEIK HPET: return as if acpi_gbl_FADT.boot_flags & 
>>> ACPI_FADT_NO_MSI\n");
>>> +    return;
>>> +
>>>      if ( unlikely(acpi_gbl_FADT.boot_flags & ACPI_FADT_NO_MSI) )
>>>          return;
>>> 
>>> 
>>> Indeed made the stalls go away ..
>> 
>> So if this time you didn't leave a no-cpuidle in place somewhere ;-)
>> this makes relatively clear that the stalls are due to the interrupts
>> coming from the HPET not reaching their destinations. I still can't
>> connect this to the $subject commit yet, though.

> Could you provide 'M' and 'V' output for the bad (stalling) case?

Could it be some priority fight / locking issue with some other MSI(X) enabled 
devices.
(which happen to be the pci-e and ... the SATA controller ... and the Ethernet 
controllers)


> Jan




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