* [PATCH 0/2] arm64/PPTT ACPI 6.3 thread flag support @ 2019-05-23 22:40 Jeremy Linton 2019-05-23 22:40 ` [PATCH 1/2] ACPI/PPTT: Add support for ACPI 6.3 thread flag Jeremy Linton 2019-05-23 22:40 ` [PATCH 2/2] arm64: topology: Use PPTT to determine if PE is a thread Jeremy Linton 0 siblings, 2 replies; 8+ messages in thread From: Jeremy Linton @ 2019-05-23 22:40 UTC (permalink / raw) To: linux-arm-kernel Cc: linux-acpi, catalin.marinas, will.deacon, rjw, lenb, sudeep.holla, Jeremy Linton ACPI 6.3 adds a flag to the CPU node to indicate whether the given CPU is a thread. Add a function to return that information for a given linux logical CPU and then utilize it while building the arm64 topology. 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 | 8 ++++-- drivers/acpi/pptt.c | 53 +++++++++++++++++++++++++++++++++++- include/linux/acpi.h | 5 ++++ 3 files changed, 62 insertions(+), 4 deletions(-) -- 2.21.0 ^ permalink raw reply [flat|nested] 8+ messages in thread
* [PATCH 1/2] ACPI/PPTT: Add support for ACPI 6.3 thread flag 2019-05-23 22:40 [PATCH 0/2] arm64/PPTT ACPI 6.3 thread flag support Jeremy Linton @ 2019-05-23 22:40 ` Jeremy Linton 2019-06-07 10:03 ` Sudeep Holla 2019-05-23 22:40 ` [PATCH 2/2] arm64: topology: Use PPTT to determine if PE is a thread Jeremy Linton 1 sibling, 1 reply; 8+ messages in thread From: Jeremy Linton @ 2019-05-23 22:40 UTC (permalink / raw) To: linux-arm-kernel Cc: linux-acpi, catalin.marinas, will.deacon, rjw, lenb, sudeep.holla, Jeremy Linton ACPI 6.3 adds a flag to the CPU node to indicate whether the given PE is a thread. Add a function to return that information for a given linux logical CPU. Signed-off-by: Jeremy Linton <jeremy.linton@arm.com> --- drivers/acpi/pptt.c | 53 +++++++++++++++++++++++++++++++++++++++++++- include/linux/acpi.h | 5 +++++ 2 files changed, 57 insertions(+), 1 deletion(-) diff --git a/drivers/acpi/pptt.c b/drivers/acpi/pptt.c index b72e6afaa8fb..6f43a0c05f61 100644 --- a/drivers/acpi/pptt.c +++ b/drivers/acpi/pptt.c @@ -517,6 +517,43 @@ static int find_acpi_cpu_topology_tag(unsigned int cpu, int level, int flag) return retval; } +/** + * check_acpi_cpu_flag() - Determine if CPU node has a flag set + * @cpu: Kernel logical CPU number + * @rev: The PPTT revision defining the flag + * @flag: The flag itself + * + * Check the node representing a CPU for a given flag. + * + * Return: -ENOENT if the PPTT doesn't exist, the CPU cannot be found or + * the table revision isn't new enough. + * Otherwise returns flag value + */ +static int check_acpi_cpu_flag(unsigned int cpu, int rev, u32 flag) +{ + struct acpi_table_header *table; + acpi_status status; + u32 acpi_cpu_id = get_acpi_id_for_cpu(cpu); + struct acpi_pptt_processor *cpu_node = NULL; + int ret = -ENONET; + + status = acpi_get_table(ACPI_SIG_PPTT, 0, &table); + if (ACPI_FAILURE(status)) { + acpi_pptt_warn_missing(); + return ret; + } + + if (table->revision >= rev) + cpu_node = acpi_find_processor_node(table, acpi_cpu_id); + + if (cpu_node) + ret = cpu_node->flags & flag; + + acpi_put_table(table); + + return ret; +} + /** * acpi_find_last_cache_level() - Determines the number of cache levels for a PE * @cpu: Kernel logical CPU number @@ -581,6 +618,21 @@ int cache_setup_acpi(unsigned int cpu) return status; } +/** + * acpi_pptt_cpu_is_thread() - Determine if logical CPU is a thread + * @cpu: Kernel logical CPU number + * + * + * Return: 1, a thread + * 0, not a thread + * -ENOENT if the PPTT doesn't exist, the CPU cannot be found or + * the table revision isn't new enough. + */ +int acpi_pptt_cpu_is_thread(unsigned int cpu) +{ + return check_acpi_cpu_flag(cpu, 2, ACPI_PPTT_ACPI_PROCESSOR_IS_THREAD); +} + /** * find_acpi_cpu_topology() - Determine a unique topology value for a given CPU * @cpu: Kernel logical CPU number @@ -641,7 +693,6 @@ int find_acpi_cpu_cache_topology(unsigned int cpu, int level) return ret; } - /** * find_acpi_cpu_topology_package() - Determine a unique CPU package value * @cpu: Kernel logical CPU number diff --git a/include/linux/acpi.h b/include/linux/acpi.h index 98440df7fe42..513833233c65 100644 --- a/include/linux/acpi.h +++ b/include/linux/acpi.h @@ -1314,10 +1314,15 @@ static inline int lpit_read_residency_count_address(u64 *address) #endif #ifdef CONFIG_ACPI_PPTT +int acpi_pptt_cpu_is_thread(unsigned int cpu); int find_acpi_cpu_topology(unsigned int cpu, int level); int find_acpi_cpu_topology_package(unsigned int cpu); int find_acpi_cpu_cache_topology(unsigned int cpu, int level); #else +static inline int acpi_pptt_cpu_is_thread(unsigned int cpu) +{ + return -EINVAL; +} static inline int find_acpi_cpu_topology(unsigned int cpu, int level) { return -EINVAL; -- 2.21.0 ^ permalink raw reply related [flat|nested] 8+ messages in thread
* Re: [PATCH 1/2] ACPI/PPTT: Add support for ACPI 6.3 thread flag 2019-05-23 22:40 ` [PATCH 1/2] ACPI/PPTT: Add support for ACPI 6.3 thread flag Jeremy Linton @ 2019-06-07 10:03 ` Sudeep Holla 0 siblings, 0 replies; 8+ messages in thread From: Sudeep Holla @ 2019-06-07 10:03 UTC (permalink / raw) To: Jeremy Linton Cc: linux-arm-kernel, linux-acpi, catalin.marinas, will.deacon, rjw, lenb, Sudeep Holla On Thu, May 23, 2019 at 05:40:14PM -0500, Jeremy Linton wrote: > ACPI 6.3 adds a flag to the CPU node to indicate whether > the given PE is a thread. Add a function to return that > information for a given linux logical CPU. > > Signed-off-by: Jeremy Linton <jeremy.linton@arm.com> > --- > drivers/acpi/pptt.c | 53 +++++++++++++++++++++++++++++++++++++++++++- > include/linux/acpi.h | 5 +++++ > 2 files changed, 57 insertions(+), 1 deletion(-) > > diff --git a/drivers/acpi/pptt.c b/drivers/acpi/pptt.c > index b72e6afaa8fb..6f43a0c05f61 100644 > --- a/drivers/acpi/pptt.c > +++ b/drivers/acpi/pptt.c > @@ -517,6 +517,43 @@ static int find_acpi_cpu_topology_tag(unsigned int cpu, int level, int flag) > return retval; > } > > +/** > + * check_acpi_cpu_flag() - Determine if CPU node has a flag set > + * @cpu: Kernel logical CPU number > + * @rev: The PPTT revision defining the flag > + * @flag: The flag itself > + * > + * Check the node representing a CPU for a given flag. > + * > + * Return: -ENOENT if the PPTT doesn't exist, the CPU cannot be found or > + * the table revision isn't new enough. > + * Otherwise returns flag value > + */ > +static int check_acpi_cpu_flag(unsigned int cpu, int rev, u32 flag) Initially, I thought we already have similar function, but I was wrong. > +{ > + struct acpi_table_header *table; > + acpi_status status; > + u32 acpi_cpu_id = get_acpi_id_for_cpu(cpu); > + struct acpi_pptt_processor *cpu_node = NULL; > + int ret = -ENONET; Unfortunately even ENONET is defined and will silently compile fine, but I assume you need ENOENT as mentioned in the comment/doc. > + > + status = acpi_get_table(ACPI_SIG_PPTT, 0, &table); > + if (ACPI_FAILURE(status)) { > + acpi_pptt_warn_missing(); > + return ret; > + } > + > + if (table->revision >= rev) > + cpu_node = acpi_find_processor_node(table, acpi_cpu_id); > + > + if (cpu_node) > + ret = cpu_node->flags & flag; > + > + acpi_put_table(table); > + > + return ret; > +} > + > /** > * acpi_find_last_cache_level() - Determines the number of cache levels for a PE > * @cpu: Kernel logical CPU number > @@ -581,6 +618,21 @@ int cache_setup_acpi(unsigned int cpu) > return status; > } > > +/** > + * acpi_pptt_cpu_is_thread() - Determine if logical CPU is a thread > + * @cpu: Kernel logical CPU number > + * > + * > + * Return: 1, a thread > + * 0, not a thread > + * -ENOENT if the PPTT doesn't exist, the CPU cannot be found or > + * the table revision isn't new enough. > + */ > +int acpi_pptt_cpu_is_thread(unsigned int cpu) > +{ > + return check_acpi_cpu_flag(cpu, 2, ACPI_PPTT_ACPI_PROCESSOR_IS_THREAD); > +} > + > /** > * find_acpi_cpu_topology() - Determine a unique topology value for a given CPU > * @cpu: Kernel logical CPU number > @@ -641,7 +693,6 @@ int find_acpi_cpu_cache_topology(unsigned int cpu, int level) > return ret; > } > > - Spurious ? > /** > * find_acpi_cpu_topology_package() - Determine a unique CPU package value > * @cpu: Kernel logical CPU number > diff --git a/include/linux/acpi.h b/include/linux/acpi.h > index 98440df7fe42..513833233c65 100644 > --- a/include/linux/acpi.h > +++ b/include/linux/acpi.h > @@ -1314,10 +1314,15 @@ static inline int lpit_read_residency_count_address(u64 *address) > #endif > > #ifdef CONFIG_ACPI_PPTT > +int acpi_pptt_cpu_is_thread(unsigned int cpu); > int find_acpi_cpu_topology(unsigned int cpu, int level); > int find_acpi_cpu_topology_package(unsigned int cpu); > int find_acpi_cpu_cache_topology(unsigned int cpu, int level); > #else > +static inline int acpi_pptt_cpu_is_thread(unsigned int cpu) > +{ > + return -EINVAL; > +} > static inline int find_acpi_cpu_topology(unsigned int cpu, int level) > { > return -EINVAL; > -- > 2.21.0 > ^ permalink raw reply [flat|nested] 8+ messages in thread
* [PATCH 2/2] arm64: topology: Use PPTT to determine if PE is a thread 2019-05-23 22:40 [PATCH 0/2] arm64/PPTT ACPI 6.3 thread flag support Jeremy Linton 2019-05-23 22:40 ` [PATCH 1/2] ACPI/PPTT: Add support for ACPI 6.3 thread flag Jeremy Linton @ 2019-05-23 22:40 ` Jeremy Linton 2019-06-06 8:49 ` John Garry 1 sibling, 1 reply; 8+ messages in thread From: Jeremy Linton @ 2019-05-23 22:40 UTC (permalink / raw) To: linux-arm-kernel Cc: linux-acpi, catalin.marinas, will.deacon, rjw, lenb, sudeep.holla, Jeremy Linton ACPI 6.3 adds a thread flag to represent if a CPU/PE is actually a thread. Given that the MPIDR_MT bit may not represent this information consistently on homogeneous machines we should prefer the PPTT flag if its available. Signed-off-by: Jeremy Linton <jeremy.linton@arm.com> --- arch/arm64/kernel/topology.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) diff --git a/arch/arm64/kernel/topology.c b/arch/arm64/kernel/topology.c index 0825c4a856e3..cbbedb53cf06 100644 --- a/arch/arm64/kernel/topology.c +++ b/arch/arm64/kernel/topology.c @@ -346,11 +346,9 @@ void remove_cpu_topology(unsigned int cpu) */ static int __init parse_acpi_topology(void) { - bool is_threaded; + int is_threaded; int cpu, topology_id; - is_threaded = read_cpuid_mpidr() & MPIDR_MT_BITMASK; - for_each_possible_cpu(cpu) { int i, cache_id; @@ -358,6 +356,10 @@ static int __init parse_acpi_topology(void) if (topology_id < 0) return topology_id; + is_threaded = acpi_pptt_cpu_is_thread(cpu); + if (is_threaded < 0) + is_threaded = read_cpuid_mpidr() & MPIDR_MT_BITMASK; + if (is_threaded) { cpu_topology[cpu].thread_id = topology_id; topology_id = find_acpi_cpu_topology(cpu, 1); -- 2.21.0 ^ permalink raw reply related [flat|nested] 8+ messages in thread
* Re: [PATCH 2/2] arm64: topology: Use PPTT to determine if PE is a thread 2019-05-23 22:40 ` [PATCH 2/2] arm64: topology: Use PPTT to determine if PE is a thread Jeremy Linton @ 2019-06-06 8:49 ` John Garry 2019-06-07 19:21 ` Jeremy Linton 0 siblings, 1 reply; 8+ messages in thread From: John Garry @ 2019-06-06 8:49 UTC (permalink / raw) To: Jeremy Linton, linux-arm-kernel Cc: linux-acpi, catalin.marinas, will.deacon, rjw, lenb, sudeep.holla, Linuxarm, Guohanjun (Hanjun Guo), wanghuiqiang, yaohongbo On 23/05/2019 23:40, Jeremy Linton wrote: > ACPI 6.3 adds a thread flag to represent if a CPU/PE is > actually a thread. Given that the MPIDR_MT bit may not > represent this information consistently on homogeneous machines > we should prefer the PPTT flag if its available. > Hi Jeremy, I was just wondering if we should look to get this support backported (when merged)? I worry about the case of a system with the CPU having MT bit in the MPIDR (while not actually threaded), i.e. the system for which these PPTT flags were added (as I understand). > Signed-off-by: Jeremy Linton <jeremy.linton@arm.com> > --- > arch/arm64/kernel/topology.c | 8 +++++--- > 1 file changed, 5 insertions(+), 3 deletions(-) > > diff --git a/arch/arm64/kernel/topology.c b/arch/arm64/kernel/topology.c > index 0825c4a856e3..cbbedb53cf06 100644 > --- a/arch/arm64/kernel/topology.c > +++ b/arch/arm64/kernel/topology.c > @@ -346,11 +346,9 @@ void remove_cpu_topology(unsigned int cpu) > */ > static int __init parse_acpi_topology(void) > { > - bool is_threaded; > + int is_threaded; > int cpu, topology_id; > > - is_threaded = read_cpuid_mpidr() & MPIDR_MT_BITMASK; > - > for_each_possible_cpu(cpu) { > int i, cache_id; > > @@ -358,6 +356,10 @@ static int __init parse_acpi_topology(void) > if (topology_id < 0) > return topology_id; > > + is_threaded = acpi_pptt_cpu_is_thread(cpu); > + if (is_threaded < 0) > + is_threaded = read_cpuid_mpidr() & MPIDR_MT_BITMASK; > + > if (is_threaded) { > cpu_topology[cpu].thread_id = topology_id; For described above scenario, this seems wrong. > topology_id = find_acpi_cpu_topology(cpu, 1); > BTW, we did test an old kernel with 6.3 PPTT bios for this on D06 (some versions have MT bit set), and it looked ok. But I am still a bit skeptical. Thanks, John ^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH 2/2] arm64: topology: Use PPTT to determine if PE is a thread 2019-06-06 8:49 ` John Garry @ 2019-06-07 19:21 ` Jeremy Linton 2019-06-10 8:30 ` John Garry 0 siblings, 1 reply; 8+ messages in thread From: Jeremy Linton @ 2019-06-07 19:21 UTC (permalink / raw) To: John Garry, linux-arm-kernel Cc: linux-acpi, catalin.marinas, will.deacon, rjw, lenb, sudeep.holla, Linuxarm, Guohanjun (Hanjun Guo), wanghuiqiang, yaohongbo Hi, Thanks for testing and looking at this. On 6/6/19 3:49 AM, John Garry wrote: > On 23/05/2019 23:40, Jeremy Linton wrote: >> ACPI 6.3 adds a thread flag to represent if a CPU/PE is >> actually a thread. Given that the MPIDR_MT bit may not >> represent this information consistently on homogeneous machines >> we should prefer the PPTT flag if its available. >> > > Hi Jeremy, > > I was just wondering if we should look to get this support backported > (when merged)? I imagine that will happen.. > > I worry about the case of a system with the CPU having MT bit in the > MPIDR (while not actually threaded), i.e. the system for which these > PPTT flags were added (as I understand). I have tested this patch on DAWN which happens to have the MT bit set, but isn't threaded, and it appears to work. > >> Signed-off-by: Jeremy Linton <jeremy.linton@arm.com> >> --- >> arch/arm64/kernel/topology.c | 8 +++++--- >> 1 file changed, 5 insertions(+), 3 deletions(-) >> >> diff --git a/arch/arm64/kernel/topology.c b/arch/arm64/kernel/topology.c >> index 0825c4a856e3..cbbedb53cf06 100644 >> --- a/arch/arm64/kernel/topology.c >> +++ b/arch/arm64/kernel/topology.c >> @@ -346,11 +346,9 @@ void remove_cpu_topology(unsigned int cpu) >> */ >> static int __init parse_acpi_topology(void) >> { >> - bool is_threaded; >> + int is_threaded; >> int cpu, topology_id; >> >> - is_threaded = read_cpuid_mpidr() & MPIDR_MT_BITMASK; >> - >> for_each_possible_cpu(cpu) { >> int i, cache_id; >> >> @@ -358,6 +356,10 @@ static int __init parse_acpi_topology(void) >> if (topology_id < 0) >> return topology_id; >> >> + is_threaded = acpi_pptt_cpu_is_thread(cpu); >> + if (is_threaded < 0) >> + is_threaded = read_cpuid_mpidr() & MPIDR_MT_BITMASK; >> + >> if (is_threaded) { >> cpu_topology[cpu].thread_id = topology_id; > > For described above scenario, this seems wrong. I'm not sure I understand the concern. This is going to ignore the MPIDR_MT bit on any machine with a PPTT revision > 1. Are you worried about the topology_id assignment? > >> topology_id = find_acpi_cpu_topology(cpu, 1); >> > > BTW, we did test an old kernel with 6.3 PPTT bios for this on D06 (some > versions have MT bit set), and it looked ok. But I am still a bit > skeptical. > > Thanks, > John > > Thanks, ^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH 2/2] arm64: topology: Use PPTT to determine if PE is a thread 2019-06-07 19:21 ` Jeremy Linton @ 2019-06-10 8:30 ` John Garry 2019-06-11 19:02 ` Jeremy Linton 0 siblings, 1 reply; 8+ messages in thread From: John Garry @ 2019-06-10 8:30 UTC (permalink / raw) To: Jeremy Linton, linux-arm-kernel Cc: linux-acpi, catalin.marinas, will.deacon, rjw, lenb, sudeep.holla, Linuxarm, Guohanjun (Hanjun Guo), wanghuiqiang, yaohongbo On 07/06/2019 20:21, Jeremy Linton wrote: > Hi, > > Thanks for testing and looking at this. > > On 6/6/19 3:49 AM, John Garry wrote: >> On 23/05/2019 23:40, Jeremy Linton wrote: >>> ACPI 6.3 adds a thread flag to represent if a CPU/PE is >>> actually a thread. Given that the MPIDR_MT bit may not >>> represent this information consistently on homogeneous machines >>> we should prefer the PPTT flag if its available. >>> >> Hi Jeremy, >> >> I was just wondering if we should look to get this support backported >> (when merged)? > > I imagine that will happen.. > >> >> I worry about the case of a system with the CPU having MT bit in the >> MPIDR (while not actually threaded), i.e. the system for which these >> PPTT flags were added (as I understand). > > I have tested this patch on DAWN which happens to have the MT bit set, > but isn't threaded, and it appears to work. Can you describe your test? > >> >>> Signed-off-by: Jeremy Linton <jeremy.linton@arm.com> >>> --- >>> arch/arm64/kernel/topology.c | 8 +++++--- >>> 1 file changed, 5 insertions(+), 3 deletions(-) >>> >>> diff --git a/arch/arm64/kernel/topology.c b/arch/arm64/kernel/topology.c >>> index 0825c4a856e3..cbbedb53cf06 100644 >>> --- a/arch/arm64/kernel/topology.c >>> +++ b/arch/arm64/kernel/topology.c >>> @@ -346,11 +346,9 @@ void remove_cpu_topology(unsigned int cpu) >>> */ >>> static int __init parse_acpi_topology(void) >>> { >>> - bool is_threaded; >>> + int is_threaded; >>> int cpu, topology_id; >>> >>> - is_threaded = read_cpuid_mpidr() & MPIDR_MT_BITMASK; >>> - >>> for_each_possible_cpu(cpu) { >>> int i, cache_id; >>> >>> @@ -358,6 +356,10 @@ static int __init parse_acpi_topology(void) >>> if (topology_id < 0) >>> return topology_id; >>> >>> + is_threaded = acpi_pptt_cpu_is_thread(cpu); >>> + if (is_threaded < 0) >>> + is_threaded = read_cpuid_mpidr() & MPIDR_MT_BITMASK; >>> + >>> if (is_threaded) { >>> cpu_topology[cpu].thread_id = topology_id; >> >> For described above scenario, this seems wrong. > > I'm not sure I understand the concern. Maybe I wasn't clear enough previously. I am saying that without this patch, then this info would not be correct. Hence the request to backport to stable. cheers, > > This is going to ignore the MPIDR_MT bit on any machine with a PPTT > revision > 1. Are you worried about the topology_id assignment? > > >> >>> topology_id = find_acpi_cpu_topology(cpu, 1); >>> >> >> BTW, we did test an old kernel with 6.3 PPTT bios for this on D06 >> (some versions have MT bit set), and it looked ok. But I am still a >> bit skeptical. >> >> Thanks, >> John >> >> > > > Thanks, > > . > ^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH 2/2] arm64: topology: Use PPTT to determine if PE is a thread 2019-06-10 8:30 ` John Garry @ 2019-06-11 19:02 ` Jeremy Linton 0 siblings, 0 replies; 8+ messages in thread From: Jeremy Linton @ 2019-06-11 19:02 UTC (permalink / raw) To: John Garry, linux-arm-kernel Cc: linux-acpi, catalin.marinas, will.deacon, rjw, lenb, sudeep.holla, Linuxarm, Guohanjun (Hanjun Guo), wanghuiqiang, yaohongbo Hi, On 6/10/19 3:30 AM, John Garry wrote: > On 07/06/2019 20:21, Jeremy Linton wrote: >> Hi, >> >> Thanks for testing and looking at this. >> >> On 6/6/19 3:49 AM, John Garry wrote: >>> On 23/05/2019 23:40, Jeremy Linton wrote: >>>> ACPI 6.3 adds a thread flag to represent if a CPU/PE is >>>> actually a thread. Given that the MPIDR_MT bit may not >>>> represent this information consistently on homogeneous machines >>>> we should prefer the PPTT flag if its available. >>>> >>> > > Hi Jeremy, > >>> >>> I was just wondering if we should look to get this support backported >>> (when merged)? >> >> I imagine that will happen.. >> >>> >>> I worry about the case of a system with the CPU having MT bit in the >>> MPIDR (while not actually threaded), i.e. the system for which these >>> PPTT flags were added (as I understand). >> >> I have tested this patch on DAWN which happens to have the MT bit set, >> but isn't threaded, and it appears to work. > > Can you describe your test? The positive test: Boot machine with/without patch, compare the output of lscpu & lstopo. Manually check/compare /sys/devices/system/cpu/cpuX/topology/* and /proc/schedstat domain masks. On DAWN we go from a system reporting 2 cores with 2 thread per core to 4 cores. I've also built firmware or injected PPTT's with varying versions/etc to sanity check cases that aren't representative of the hardware. > >> >>> >>>> Signed-off-by: Jeremy Linton <jeremy.linton@arm.com> >>>> --- >>>> arch/arm64/kernel/topology.c | 8 +++++--- >>>> 1 file changed, 5 insertions(+), 3 deletions(-) >>>> >>>> diff --git a/arch/arm64/kernel/topology.c >>>> b/arch/arm64/kernel/topology.c >>>> index 0825c4a856e3..cbbedb53cf06 100644 >>>> --- a/arch/arm64/kernel/topology.c >>>> +++ b/arch/arm64/kernel/topology.c >>>> @@ -346,11 +346,9 @@ void remove_cpu_topology(unsigned int cpu) >>>> */ >>>> static int __init parse_acpi_topology(void) >>>> { >>>> - bool is_threaded; >>>> + int is_threaded; >>>> int cpu, topology_id; >>>> >>>> - is_threaded = read_cpuid_mpidr() & MPIDR_MT_BITMASK; >>>> - >>>> for_each_possible_cpu(cpu) { >>>> int i, cache_id; >>>> >>>> @@ -358,6 +356,10 @@ static int __init parse_acpi_topology(void) >>>> if (topology_id < 0) >>>> return topology_id; >>>> >>>> + is_threaded = acpi_pptt_cpu_is_thread(cpu); >>>> + if (is_threaded < 0) >>>> + is_threaded = read_cpuid_mpidr() & MPIDR_MT_BITMASK; >>>> + >>>> if (is_threaded) { >>>> cpu_topology[cpu].thread_id = topology_id; >>> >>> For described above scenario, this seems wrong. >> >> I'm not sure I understand the concern. > > Maybe I wasn't clear enough previously. I am saying that without this > patch, then this info would not be correct. Hence the request to > backport to stable. > > cheers, > >> >> This is going to ignore the MPIDR_MT bit on any machine with a PPTT >> revision > 1. Are you worried about the topology_id assignment? >> >> >>> >>>> topology_id = find_acpi_cpu_topology(cpu, 1); >>>> >>> >>> BTW, we did test an old kernel with 6.3 PPTT bios for this on D06 >>> (some versions have MT bit set), and it looked ok. But I am still a >>> bit skeptical. >>> >>> Thanks, >>> John >>> >>> >> >> >> Thanks, >> >> . >> > > ^ permalink raw reply [flat|nested] 8+ messages in thread
end of thread, other threads:[~2019-06-11 19:06 UTC | newest] Thread overview: 8+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2019-05-23 22:40 [PATCH 0/2] arm64/PPTT ACPI 6.3 thread flag support Jeremy Linton 2019-05-23 22:40 ` [PATCH 1/2] ACPI/PPTT: Add support for ACPI 6.3 thread flag Jeremy Linton 2019-06-07 10:03 ` Sudeep Holla 2019-05-23 22:40 ` [PATCH 2/2] arm64: topology: Use PPTT to determine if PE is a thread Jeremy Linton 2019-06-06 8:49 ` John Garry 2019-06-07 19:21 ` Jeremy Linton 2019-06-10 8:30 ` John Garry 2019-06-11 19:02 ` Jeremy Linton
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