On 3/15/21 4:12 PM, Daniel Henrique Barboza wrote: > > > On 3/12/21 11:31 AM, Cédric Le Goater wrote: >> Initial commit 15863ff3b8da ("powerpc: Make chip-id information >> available to userspace") introduce a cpu_to_chip_id() routine for the >> PowerNV platform using the "ibm,chip-id" property to query the chip id >> of a CPU. But PAPR does not specify such a property and the node id >> query is broken. >> >> Use cpu_to_node() instead which guarantees to have a correct value on >> all platforms, PowerNV an pSeries. > > It is worth mentioning that that this patch will change how > topology_physical_package_id() represents in a QEMU guest. Right now, > ibm,chip-id > in QEMU is matching the socket-id. After this patch, > topology_physical_package_id() > will now match the NUMA id of the CPU.
yes. I should have added some more background. LPARs are impacted by the use of ibm,chip-id because the property does not exist under PowerVM and the topology-id in sysfs is always -1 even if NUMA nodes are defined. Under QEMU/KVM, ibm,chip-id is badly calculated when using uncommon SMT configuration. This leads to a bogus topology-id value being exported in sysfs. The use of cpu_to_node() guarantees to have a correct NUMA node id under both environments QEMU/KVM and PowerVM. On the PowerNV platform, the numa node id returned by cpu_to_node() is computed from the "ibm,associativity" property of the CPU. Its value is built from the OPAL chip id and is equivalent to ibm,chip-id. May be I should rephrase the commit log in a v2 ? C. > Reviewed-by: Daniel Henrique Barboza <danielhb...@gmail.com> > Tested-by: Daniel Henrique Barboza <danielhb...@gmail.com> > >> >> Cc: Nathan Lynch <nath...@linux.ibm.com> >> Cc: Srikar Dronamraju <sri...@linux.vnet.ibm.com> >> Cc: Vasant Hegde <hegdevas...@linux.vnet.ibm.com> >> Signed-off-by: Cédric Le Goater <c...@kaod.org> >> --- >> arch/powerpc/include/asm/topology.h | 2 +- >> 1 file changed, 1 insertion(+), 1 deletion(-) >> >> diff --git a/arch/powerpc/include/asm/topology.h >> b/arch/powerpc/include/asm/topology.h >> index 3beeb030cd78..887c42a4e43d 100644 >> --- a/arch/powerpc/include/asm/topology.h >> +++ b/arch/powerpc/include/asm/topology.h >> @@ -123,7 +123,7 @@ static inline int cpu_to_coregroup_id(int cpu) >> #ifdef CONFIG_PPC64 >> #include <asm/smp.h> >> -#define topology_physical_package_id(cpu) (cpu_to_chip_id(cpu)) >> +#define topology_physical_package_id(cpu) (cpu_to_node(cpu)) >> #define topology_sibling_cpumask(cpu) (per_cpu(cpu_sibling_map, cpu)) >> #define topology_core_cpumask(cpu) (cpu_cpu_mask(cpu)) >>