Joerg Roedel 90e970cfd6 iommu/amd: Fix loop timeout issue in iommu_ga_log_enable()
commit 9b45a7738eec52bf0f5d8d3d54e822962781c5f2 upstream.

The polling loop for the register change in iommu_ga_log_enable() needs
to have a udelay() in it.  Otherwise the CPU might be faster than the
IOMMU hardware and wrongly trigger the WARN_ON() further down the code
stream. Use a 10us for udelay(), has there is some hardware where
activation of the GA log can take more than a 100ms.

A future optimization should move the activation check of the GA log
to the point where it gets used for the first time. But that is a
bigger change and not suitable for a fix.

Fixes: 8bda0cfbdc1a ("iommu/amd: Detect and initialize guest vAPIC log")
Signed-off-by: Joerg Roedel <jroedel@suse.de>
Link: https://lore.kernel.org/r/20220204115537.3894-1-joro@8bytes.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-02-08 18:15:29 +01:00
..
2020-09-03 11:21:16 +02:00
2017-12-20 10:07:28 +01:00