Hi Henry, On 26/02/2024 04:01, Henry Wang wrote: > In the common sysctl command XEN_SYSCTL_physinfo, the value of > cores_per_socket is calculated based on the cpu_core_mask of CPU0. > Currently on Arm this is a fixed value 1 (can be checked via xl info), > which is not correct. This is because during the Arm CPU online > process at boot time, setup_cpu_sibling_map() only sets the per-cpu > cpu_core_mask for itself. > > cores_per_socket refers to the number of cores that belong to the same > socket (NUMA node). Currently Xen on Arm does not support physical > CPU hotplug and NUMA. Therefore if the MT bit (bit 24) in MPIDR_EL1 > is 0, cores_per_socket means all possible CPUs detected from the device > tree. Setting the per-cpu cpu_core_mask in setup_cpu_sibling_map() > accordingly. Drop the in-code comment which seems to be outdated. > > Signed-off-by: Henry Wang <[email protected]> NIT: You first sent this patch as part of NUMA series: https://lore.kernel.org/xen-devel/[email protected]/ Shouldn't you retain the Arm's authorship?
> --- > xen/arch/arm/smpboot.c | 6 +++++- > 1 file changed, 5 insertions(+), 1 deletion(-) > > diff --git a/xen/arch/arm/smpboot.c b/xen/arch/arm/smpboot.c > index a84e706d77..d616778655 100644 > --- a/xen/arch/arm/smpboot.c > +++ b/xen/arch/arm/smpboot.c > @@ -66,7 +66,6 @@ static bool cpu_is_dead; > > /* ID of the PCPU we're running on */ > DEFINE_PER_CPU(unsigned int, cpu_id); > -/* XXX these seem awfully x86ish... */ > /* representing HT siblings of each logical CPU */ > DEFINE_PER_CPU_READ_MOSTLY(cpumask_var_t, cpu_sibling_mask); > /* representing HT and core siblings of each logical CPU */ > @@ -89,6 +88,11 @@ static int setup_cpu_sibling_map(int cpu) > cpumask_set_cpu(cpu, per_cpu(cpu_sibling_mask, cpu)); > cpumask_set_cpu(cpu, per_cpu(cpu_core_mask, cpu)); > > + /* PE not implemented using a multithreading type approach. */ > + if ( system_cpuinfo.mpidr.mt == 0 ) Do we need this check? It mt was true, cpu_sibling_mask would be incorrect anyway (it would still be 1). ~Michal
