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arm64: topology: move store_cpu_topology() to shared code 

arm64's method of defining a default cpu topology requires only minimal
changes to apply to RISC-V also. The current arm64 implementation exits
early in a uniprocessor configuration by reading MPIDR & claiming that
uniprocessor can rely on the default values.

This is appears to be a hangover from prior to '3102bc0e6ac7 ("arm64:
topology: Stop using MPIDR for topology information")', because the
current code just assigns default values for multiprocessor systems.

With the MPIDR references removed, store_cpu_topolgy() can be moved to
the common arch_topology code.

Reviewed-by: Sudeep Holla <sudeep.holla@arm.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Reviewed-by: Atish Patra <atishp@rivosinc.com>
Signed-off-by: Conor Dooley <conor.dooley@microchip.com>
This commit is contained in:
Conor Dooley 2022-07-15 18:51:55 +01:00
parent 568035b01c
commit 456797da79
2 changed files with 19 additions and 40 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

40
arch/arm64/kernel/topology.c
View File

@ -22,46 +22,6 @@
#include <asm/cputype.h>
#include <asm/topology.h>
void store_cpu_topology(unsigned int cpuid)
{
struct cpu_topology *cpuid_topo = &cpu_topology[cpuid];
u64 mpidr;
if (cpuid_topo->package_id != -1)
goto topology_populated;
mpidr = read_cpuid_mpidr();
/* Uniprocessor systems can rely on default topology values */
if (mpidr & MPIDR_UP_BITMASK)
return;
/*
* This would be the place to create cpu topology based on MPIDR.
*
* However, it cannot be trusted to depict the actual topology; some
* pieces of the architecture enforce an artificial cap on Aff0 values
* (e.g. GICv3's ICC_SGI1R_EL1 limits it to 15), leading to an
* artificial cycling of Aff1, Aff2 and Aff3 values. IOW, these end up
* having absolutely no relationship to the actual underlying system
* topology, and cannot be reasonably used as core / package ID.
*
* If the MT bit is set, Aff0 *could* be used to define a thread ID, but
* we still wouldn't be able to obtain a sane core ID. This means we
* need to entirely ignore MPIDR for any topology deduction.
*/
cpuid_topo->thread_id = -1;
cpuid_topo->core_id = cpuid;
cpuid_topo->package_id = cpu_to_node(cpuid);
pr_debug("CPU%u: cluster %d core %d thread %d mpidr %#016llx\n",
cpuid, cpuid_topo->package_id, cpuid_topo->core_id,
cpuid_topo->thread_id, mpidr);
topology_populated:
update_siblings_masks(cpuid);
}
#ifdef CONFIG_ACPI
static bool __init acpi_cpu_is_threaded(int cpu)
{

19
drivers/base/arch_topology.c
View File

@ -841,4 +841,23 @@ void __init init_cpu_topology(void)
return;
}
}
void store_cpu_topology(unsigned int cpuid)
{
struct cpu_topology *cpuid_topo = &cpu_topology[cpuid];
if (cpuid_topo->package_id != -1)
goto topology_populated;
cpuid_topo->thread_id = -1;
cpuid_topo->core_id = cpuid;
cpuid_topo->package_id = cpu_to_node(cpuid);
pr_debug("CPU%u: package %d core %d thread %d\n",
cpuid, cpuid_topo->package_id, cpuid_topo->core_id,
cpuid_topo->thread_id);
topology_populated:
update_siblings_masks(cpuid);
}
#endif