Re: [PATCH for-4.20 v3 0/5] xen/x86: prevent local APIC errors at shutdown

[Jan Beulich <jbeulich@xxxxxxxx>]

On 12.02.2025 09:33, Oleksii Kurochko wrote:
> 
> On 2/11/25 7:39 PM, Roger Pau Monné wrote:
>> On Tue, Feb 11, 2025 at 12:02:04PM +0100, Roger Pau Monne wrote:
>>> Hello,
>>>
>>> The following series aims to prevent local APIC errors from stalling the
>>> shtudown process.  On XenServer testing we have seen reports of AMD
>>> boxes sporadically getting stuck in a spam of:
>>>
>>> APIC error on CPU0: 00(08), Receive accept error
>>>
>>> Messages during shutdown, as a result of device interrupts targeting
>>> CPUs that are offline (and have the local APIC disabled).
>>>
>>> First patch strictly solves the issue of shutdown getting stuck, further
>>> patches aim to quiesce interrupts from all devices (known by Xen) as an
>>> attempt to prevent a spurious "APIC error on CPU0: 00(00)" plus also
>>> make kexec more reliable.
>>>
>>> Thanks, Roger.
>>>
>>> Roger Pau Monne (5):
>>>    x86/shutdown: offline APs with interrupts disabled on all CPUs
>>>    x86/irq: drop fixup_irqs() parameters
>>>    x86/smp: perform disabling on interrupts ahead of AP shutdown
>>>    x86/pci: disable MSI(-X) on all devices at shutdown
>>>    x86/iommu: disable interrupts at shutdown
>> This is now fully reviewed, can I get your opinion (and
>> release-acked-by) on which patches we should take for 4.20?
> 
> If my understanding is correct to unblock shutdown process, it is enough just
> to have only first patch merged, correct? So the first patch should be merged.
> 
> As second patch doesn't have functional changes, IMO, it could be merged to
> despite of the fact we have Hard code freeze period.
> 
> All other patches, I would like to ask additional opinion (as I am an expert 
> in x86),
> at first glance it looks like an absence of these patches in staging branch 
> will
> lead only to triggering "Receive accept error" which I believe won't block 
> shutdown
> process, so these patches could be postponed until 4.21. On other side, if it 
> is
> low-risk fixes then we could consider to merge them now.

I'm not Roger, but as a data point: While I'm uncertain about patch 2, all
others in this series will very likely be backported anyway.

Jan