Patch "riscv: topology: fix default topology reporting" has been added to the 5.4-stable tree

[gregkh at linuxfoundation.org]

This is a note to let you know that I've just added the patch titled

    riscv: topology: fix default topology reporting

to the 5.4-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     riscv-topology-fix-default-topology-reporting.patch
and it can be found in the queue-5.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable at vger.kernel.org> know about it.


>From foo at baz Thu Oct 27 12:19:05 PM CEST 2022
From: Conor Dooley <conor.dooley at microchip.com>
Date: Wed, 19 Oct 2022 13:52:10 +0100
Subject: riscv: topology: fix default topology reporting
To: <stable at vger.kernel.org>
Cc: <conor.dooley at microchip.com>, <Brice.Goglin at inria.fr>, <atishp at atishpatra.org>, <catalin.marinas at arm.com>, <gregkh at linuxfoundation.org>, <linux-arm-kernel at lists.infradead.org>, <linux-kernel at vger.kernel.org>, <linux-riscv at lists.infradead.org>, <palmer at dabbelt.com>, <sudeep.holla at arm.com>, <will at kernel.org>, Atish Patra <atishp at rivosinc.com>
Message-ID: <20221019125209.2844943-2-conor.dooley at microchip.com>

From: Conor Dooley <conor.dooley at microchip.com>

commit fbd92809997a391f28075f1c8b5ee314c225557c upstream.

RISC-V has no sane defaults to fall back on where there is no cpu-map
in the devicetree.
Without sane defaults, the package, core and thread IDs are all set to
-1. This causes user-visible inaccuracies for tools like hwloc/lstopo
which rely on the sysfs cpu topology files to detect a system's
topology.

On a PolarFire SoC, which should have 4 harts with a thread each,
lstopo currently reports:

Machine (793MB total)
  Package L#0
    NUMANode L#0 (P#0 793MB)
    Core L#0
      L1d L#0 (32KB) + L1i L#0 (32KB) + PU L#0 (P#0)
      L1d L#1 (32KB) + L1i L#1 (32KB) + PU L#1 (P#1)
      L1d L#2 (32KB) + L1i L#2 (32KB) + PU L#2 (P#2)
      L1d L#3 (32KB) + L1i L#3 (32KB) + PU L#3 (P#3)

Adding calls to store_cpu_topology() in {boot,smp} hart bringup code
results in the correct topolgy being reported:

Machine (793MB total)
  Package L#0
    NUMANode L#0 (P#0 793MB)
    L1d L#0 (32KB) + L1i L#0 (32KB) + Core L#0 + PU L#0 (P#0)
    L1d L#1 (32KB) + L1i L#1 (32KB) + Core L#1 + PU L#1 (P#1)
    L1d L#2 (32KB) + L1i L#2 (32KB) + Core L#2 + PU L#2 (P#2)
    L1d L#3 (32KB) + L1i L#3 (32KB) + Core L#3 + PU L#3 (P#3)

CC: stable at vger.kernel.org # 456797da792f: arm64: topology: move store_cpu_topology() to shared code
Fixes: 03f11f03dbfe ("RISC-V: Parse cpu topology during boot.")
Reported-by: Brice Goglin <Brice.Goglin at inria.fr>
Link: https://github.com/open-mpi/hwloc/issues/536
Reviewed-by: Sudeep Holla <sudeep.holla at arm.com>
Reviewed-by: Atish Patra <atishp at rivosinc.com>
Signed-off-by: Conor Dooley <conor.dooley at microchip.com>
Signed-off-by: Greg Kroah-Hartman <gregkh at linuxfoundation.org>
---
 arch/riscv/Kconfig          |    2 +-
 arch/riscv/kernel/smpboot.c |    4 +++-
 2 files changed, 4 insertions(+), 2 deletions(-)

--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -51,7 +51,7 @@ config RISCV
 	select PCI_MSI if PCI
 	select RISCV_TIMER
 	select GENERIC_IRQ_MULTI_HANDLER
-	select GENERIC_ARCH_TOPOLOGY if SMP
+	select GENERIC_ARCH_TOPOLOGY
 	select ARCH_HAS_PTE_SPECIAL
 	select ARCH_HAS_MMIOWB
 	select HAVE_EBPF_JIT if 64BIT
--- a/arch/riscv/kernel/smpboot.c
+++ b/arch/riscv/kernel/smpboot.c
@@ -46,6 +46,8 @@ void __init smp_prepare_cpus(unsigned in
 {
 	int cpuid;
 
+	store_cpu_topology(smp_processor_id());
+
 	/* This covers non-smp usecase mandated by "nosmp" option */
 	if (max_cpus == 0)
 		return;
@@ -142,8 +144,8 @@ asmlinkage __visible void __init smp_cal
 	current->active_mm = mm;
 
 	trap_init();
+	store_cpu_topology(smp_processor_id());
 	notify_cpu_starting(smp_processor_id());
-	update_siblings_masks(smp_processor_id());
 	set_cpu_online(smp_processor_id(), 1);
 	/*
 	 * Remote TLB flushes are ignored while the CPU is offline, so emit


Patches currently in stable-queue which might be from conor.dooley at microchip.com are

queue-5.4/arm64-topology-move-store_cpu_topology-to-shared-code.patch
queue-5.4/riscv-topology-fix-default-topology-reporting.patch