Draft: [AMDSERVER 9.5 Bug] Skip initialization of GHES_ASSIST structures

JIRA: https://issues.redhat.com/browse/RHEL-34749

ACPI: APEI: Skip initialization of GHES_ASSIST structures for Machine Check Architecture

To support GHES_ASSIST on Machine Check Architecture (MCA) error sources,
a set of GHES structures is provided by the system firmware for each MCA
error source. Each of these sets consists of a GHES structure for each MCA
bank on each logical CPU, with all structures of a set sharing a common
Related Source ID, equal to the Source ID of one of the MCA error source
structures.[1] On SOCs with large core counts, this typically equates to
tens of thousands of GHES_ASSIST structures for MCA under
"/sys/bus/platform/drivers/GHES".

Support for GHES_ASSIST however, hasn't been implemented in the kernel. As
such, the information provided through these structures is not consumed by
Linux. Moreover, these GHES_ASSIST structures for MCA, which are supposed
to provide supplemental information in context of an error reported by
hardware, are setup as independent error sources by the kernel during HEST
initialization.

Additionally, if the Type field of the Notification structure, associated
with these GHES_ASSIST structures for MCA, is set to Polled, the kernel
sets up a timer for each individual structure. The duration of the timer
is derived from the Poll Interval field of the Notification structure. On
SOCs with high core counts, this will result in tens of thousands of
timers expiring periodically causing unnecessary preemptions and wastage
of CPU cycles. The problem will particularly intensify if Poll Interval
duration is not sufficiently high.

Since GHES_ASSIST support is not present in kernel, skip initialization
of GHES_ASSIST structures for MCA to eliminate their performance impact.

[1] ACPI specification 6.5, section 18.7

Signed-off-by: Avadhut Naik <avadhut.naik@amd.com>
Reviewed-by: Yazen Ghannam <yazen.ghannam@amd.com>
Reviewed-by: Tony Luck <tony.luck@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
(cherry picked from commit 8ec7071385508822892cabc2c0cb74333859407a)

Signed-off-by: CKI Backport Bot cki-ci-bot+cki-gitlab-backport-bot@redhat.com