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* [RFC PATCH 0/3] ACPI, arm64: Backport for ACPI PPTT 6.3 thread flag for stable 4.19.x
@ 2019-10-10 13:29 John Garry
  2019-10-10 13:29 ` [RFC PATCH 1/3] ACPICA: ACPI 6.3: PPTT add additional fields in Processor Structure Flags John Garry
                   ` (3 more replies)
  0 siblings, 4 replies; 7+ messages in thread
From: John Garry @ 2019-10-10 13:29 UTC (permalink / raw)
  To: catalin.marinas, will, rjw, lenb, robert.moore, erik.schmauss,
	sudeep.holla, rrichter, jeremy.linton
  Cc: linux-arm-kernel, linux-kernel, linux-acpi, linuxarm, gregkh,
	guohanjun, wanghuiqiang, John Garry

This series is a backport of the ACPI PPTT 6.3 thread flag feature for
supporting arm64 systems.

The background is that some arm64 implementations are broken, in that they
incorrectly advertise that a CPU is mutli-threaded, when it is not - the
HiSilicon Taishanv110 rev 2, aka tsv110, being an example.

This leads to the system topology being incorrect. The reason being that
arm64 topology code uses a combination of ACPI PPTT (Processor Properties
Topology Table) and the system MPIDR (Multiprocessor Affinity Register) MT
bit to determine the topology.

Until ACPI 6.3, the PPTT did not have any method to determine whether
a CPU was multi-threaded, so only the MT bit is used - hence the
broken topology for some systems.

In ACPI 6.3, a PPTT thread flag was introduced, which - when supported -
would be used by the kernel to determine really if a CPU is multi-threaded
or not, so that we don't get incorrect topology.

Note: I'm sending this as an RFC before sending to stable proper. I also
have a 5.2 and 5.3 backport which are almost the same, and only
significant change being that the ACPICA patch is not required.

Erik Schmauss (1):
  ACPICA: ACPI 6.3: PPTT add additional fields in Processor Structure
    Flags

Jeremy Linton (2):
  ACPI/PPTT: Add support for ACPI 6.3 thread flag
  arm64: topology: Use PPTT to determine if PE is a thread

 arch/arm64/kernel/topology.c | 19 ++++++++++---
 drivers/acpi/pptt.c          | 52 ++++++++++++++++++++++++++++++++++++
 include/acpi/actbl2.h        |  7 +++--
 include/linux/acpi.h         |  5 ++++
 4 files changed, 77 insertions(+), 6 deletions(-)

-- 
2.17.1


^ permalink raw reply	[flat|nested] 7+ messages in thread

end of thread, other threads:[~2019-10-11  0:54 UTC | newest]

Thread overview: 7+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2019-10-10 13:29 [RFC PATCH 0/3] ACPI, arm64: Backport for ACPI PPTT 6.3 thread flag for stable 4.19.x John Garry
2019-10-10 13:29 ` [RFC PATCH 1/3] ACPICA: ACPI 6.3: PPTT add additional fields in Processor Structure Flags John Garry
2019-10-10 14:22   ` Moore, Robert
2019-10-10 14:28     ` John Garry
2019-10-10 13:29 ` [RFC PATCH 2/3] ACPI/PPTT: Add support for ACPI 6.3 thread flag John Garry
2019-10-10 13:29 ` [RFC PATCH 3/3] arm64: topology: Use PPTT to determine if PE is a thread John Garry
2019-10-11  0:53 ` [RFC PATCH 0/3] ACPI, arm64: Backport for ACPI PPTT 6.3 thread flag for stable 4.19.x Hanjun Guo

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