Re: [PATCH] x86/events/amd/iommu: Fix invalid Perf result due to IOMMU PMC power-gating

From: Peter Zijlstra
Date: Tue May 04 2021 - 05:39:55 EST

On Tue, May 04, 2021 at 01:52:36AM -0500, Suravee Suthikulpanit wrote:

> 2. Since AMD IOMMU PMU does not support interrupt mode, the logic
> can be simplified to always start counting with value zero,
> and accumulate the counter value when stopping without the need
> to keep track and reprogram the counter with the previously read
> counter value.

This relies on the hardware counter being the full 64bit wide, is it?