Bug in XEN support with IPIs?

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Bug in XEN support with IPIs?

McCarthy, Brian
it appears, that for FreeBSD XEN guests with SMP support, The IPIs get messed up by intr_shuffle_irqs. The symptom is a smp_ipi_mtx
timeout during TLB shootdown. I've seen this mentioned in e-mails, with the solution (without explanation) being to enable EARLY_AP_STARTUP.
The reason this works in BSD11 is that int_shuffle_irqs is conditionalixed out on EARLY_AP_STARTUP. The real solution seems to be that
xi_cpu and/or ie_cpu should be set. I'm trying to figure out where that would be (for our somewhat modified FreeBSD kernel).

-Brian McCarthy, NetApp
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Re: Bug in XEN support with IPIs?

Colin Percival
On 10/19/18 9:40 AM, McCarthy, Brian wrote:
> it appears, that for FreeBSD XEN guests with SMP support, The IPIs get messed up by intr_shuffle_irqs. The symptom is a smp_ipi_mtx
> timeout during TLB shootdown. I've seen this mentioned in e-mails, with the solution (without explanation) being to enable EARLY_AP_STARTUP.
> The reason this works in BSD11 is that int_shuffle_irqs is conditionalixed out on EARLY_AP_STARTUP. The real solution seems to be that
> xi_cpu and/or ie_cpu should be set. I'm trying to figure out where that would be (for our somewhat modified FreeBSD kernel).

Which version are you looking at?  We fixed a bug along these lines just
about a month ago -- see r338624-338631.

--
Colin Percival
Security Officer Emeritus, FreeBSD | The power to serve
Founder, Tarsnap | www.tarsnap.com | Online backups for the truly paranoid
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