Re: xl create/save throwing errors

[Petr Beneš <w1benny@xxxxxxxxx>]

On Wed, Feb 26, 2025 at 4:23 AM Petr Beneš <w1benny@xxxxxxxxx> wrote:
> I finally managed to capture a few non-corrupted crashdumps.
> The cause of crash always points to the same symbol:
> nt!KiIpiProcessRequests+0x193

It appears that the Windows likes to manage its own IPI - i.e.
KiIpiSendRequest stores the request packet to the
KPRCB->RequestMailbox, and then KiIpiProcessRequests takes that
request from the RequestMailbox.
If someone externally interferes with that (Xen?) and triggers IPI
that Windows doesn't expect, then Windows crashes - likely because it
takes some invalid/stale value from the RequestMailbox (which wasn't
set properly by KiIpiSendRequest).

This is just a wild guess and it might be wrong. But clearly,
something weird is happening around IPI during the xl save process
that Windows doesn't like.

P.