tree d17dd1f677841f1c2f352019508861690430dfa6
parent d9772c6108db42dc7b186cc699fe597d3f40c302
author Frederic Barrat <fbarrat@linux.ibm.com> 1655302901 +0200
committer Reza Arbab <arbab@linux.ibm.com> 1657030934 -0500

interrupts: Speed up opal interrupts scanning

When looking for which interrupts are serviced by opal, we scan all
sources and query every single interrupt to know if it's for linux or
opal. An optimization was made so that if the source doesn't have an
'interrupt' op (=the handler) or an 'attributes' op (to do the
query), then we can skip the source. That's all good.

However, when xive was introduced, the 'irq_source' defining those ops
was wrapped in a 'xive_src' source which adds a level of indirection
for those 'attributes' and 'interrupt' ops. So the previous
optimization no longer works: the 'attributes' and 'interrupt' ops are
defined from the wrapper, but if we could look past the indirection,
we would realize they are not.

That is getting problematic for the rather large generic IPIs
source. We have 8 million such interrupts defined per chip on P10 and
because the above optimization is no longer kicking in, we are now
querying every single one of them to know if it is for opal. Real
hardware swallows it without much difficulty, but simulators
don't. Running qemu on my laptop, the full scan takes ~12 seconds per
chip!

This patch adds a callback for an interrupt source to report whether
it has opal interrupts. If the source doesn't define it, then we
fallback to looking at the 'interrupt' and 'attributes' ops, like
before, as it is still useful on P8. We can then define that new
callback on the xive sources, allowing to look past the indirection
level and skip scanning the source when appropriate.

Signed-off-by: Frederic Barrat <fbarrat@linux.ibm.com>
Signed-off-by: Reza Arbab <arbab@linux.ibm.com>