[v8,11/13] arm64: topology: enable ACPI/PPTT based CPU topology

Message ID 20180425233121.13270-12-jeremy.linton@arm.com
State Accepted
Commit 2f0a5d107e1fd6250a3a0469892a6c47a8ca933b
Headers show
Series
  • Support PPTT for ARM64
Related show

Commit Message

Jeremy Linton April 25, 2018, 11:31 p.m.
Propagate the topology information from the PPTT tree to the
cpu_topology array. We can get the thread id and core_id by assuming
certain levels of the PPTT tree correspond to those concepts.
The package_id is flagged in the tree and can be found by calling
find_acpi_cpu_topology_package() which terminates
its search when it finds an ACPI node flagged as the physical
package. If the tree doesn't contain enough levels to represent
all of the requested levels then the root node will be returned
for all subsequent levels.

Signed-off-by: Jeremy Linton <jeremy.linton@arm.com>

---
 arch/arm64/kernel/topology.c | 45 +++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 44 insertions(+), 1 deletion(-)

-- 
2.13.6

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Comments

Rafael J. Wysocki May 2, 2018, 8:24 a.m. | #1
On Tue, May 1, 2018 at 4:46 PM, Sudeep Holla <sudeep.holla@arm.com> wrote:
>

>

> On 26/04/18 00:31, Jeremy Linton wrote:

>> Propagate the topology information from the PPTT tree to the

>> cpu_topology array. We can get the thread id and core_id by assuming

>> certain levels of the PPTT tree correspond to those concepts.

>> The package_id is flagged in the tree and can be found by calling

>> find_acpi_cpu_topology_package() which terminates

>> its search when it finds an ACPI node flagged as the physical

>> package. If the tree doesn't contain enough levels to represent

>> all of the requested levels then the root node will be returned

>> for all subsequent levels.

>>

>

> Acked-by: Sudeep Holla <sudeep.holla@arm.com>

>

> [..]

>

>> @@ -304,6 +345,8 @@ void __init init_cpu_topology(void)

>>        * Discard anything that was parsed if we hit an error so we

>>        * don't use partial information.

>>        */

>> -     if (of_have_populated_dt() && parse_dt_topology())

>> +     if ((!acpi_disabled) && parse_acpi_topology())

>

> [nit] not sure if extra () is need above,


No, it isn't.

> but I am fine either way.


The redundant parens need to go away, really.
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Jeremy Linton May 2, 2018, 10:35 p.m. | #2
Hi,

On 05/02/2018 03:24 AM, Rafael J. Wysocki wrote:
> On Tue, May 1, 2018 at 4:46 PM, Sudeep Holla <sudeep.holla@arm.com> wrote:

>>

>>

>> On 26/04/18 00:31, Jeremy Linton wrote:

>>> Propagate the topology information from the PPTT tree to the

>>> cpu_topology array. We can get the thread id and core_id by assuming

>>> certain levels of the PPTT tree correspond to those concepts.

>>> The package_id is flagged in the tree and can be found by calling

>>> find_acpi_cpu_topology_package() which terminates

>>> its search when it finds an ACPI node flagged as the physical

>>> package. If the tree doesn't contain enough levels to represent

>>> all of the requested levels then the root node will be returned

>>> for all subsequent levels.

>>>

>>

>> Acked-by: Sudeep Holla <sudeep.holla@arm.com>

>>

>> [..]

>>

>>> @@ -304,6 +345,8 @@ void __init init_cpu_topology(void)

>>>         * Discard anything that was parsed if we hit an error so we

>>>         * don't use partial information.

>>>         */

>>> -     if (of_have_populated_dt() && parse_dt_topology())

>>> +     if ((!acpi_disabled) && parse_acpi_topology())

>>

>> [nit] not sure if extra () is need above,

> 

> No, it isn't.

> 

>> but I am fine either way.

> 

> The redundant parens need to go away, really.

> 


Yah, I missed this one, is there a linter everyone is using that finds 
these?

Thanks,
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Morten Rasmussen May 3, 2018, 3:15 p.m. | #3
On Wed, Apr 25, 2018 at 06:31:19PM -0500, Jeremy Linton wrote:
> Propagate the topology information from the PPTT tree to the

> cpu_topology array. We can get the thread id and core_id by assuming

> certain levels of the PPTT tree correspond to those concepts.

> The package_id is flagged in the tree and can be found by calling

> find_acpi_cpu_topology_package() which terminates

> its search when it finds an ACPI node flagged as the physical

> package. If the tree doesn't contain enough levels to represent

> all of the requested levels then the root node will be returned

> for all subsequent levels.

> 

> Signed-off-by: Jeremy Linton <jeremy.linton@arm.com>


Acked-by: Morten Rasmussen <morten.rasmussen@arm.com>

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Patch

diff --git a/arch/arm64/kernel/topology.c b/arch/arm64/kernel/topology.c
index dc18b1e53194..bd1aae438a31 100644
--- a/arch/arm64/kernel/topology.c
+++ b/arch/arm64/kernel/topology.c
@@ -11,6 +11,7 @@ 
  * for more details.
  */
 
+#include <linux/acpi.h>
 #include <linux/arch_topology.h>
 #include <linux/cpu.h>
 #include <linux/cpumask.h>
@@ -22,6 +23,7 @@ 
 #include <linux/sched.h>
 #include <linux/sched/topology.h>
 #include <linux/slab.h>
+#include <linux/smp.h>
 #include <linux/string.h>
 
 #include <asm/cpu.h>
@@ -296,6 +298,45 @@  static void __init reset_cpu_topology(void)
 	}
 }
 
+#ifdef CONFIG_ACPI
+/*
+ * Propagate the topology information of the processor_topology_node tree to the
+ * cpu_topology array.
+ */
+static int __init parse_acpi_topology(void)
+{
+	bool is_threaded;
+	int cpu, topology_id;
+
+	is_threaded = read_cpuid_mpidr() & MPIDR_MT_BITMASK;
+
+	for_each_possible_cpu(cpu) {
+		topology_id = find_acpi_cpu_topology(cpu, 0);
+		if (topology_id < 0)
+			return topology_id;
+
+		if (is_threaded) {
+			cpu_topology[cpu].thread_id = topology_id;
+			topology_id = find_acpi_cpu_topology(cpu, 1);
+			cpu_topology[cpu].core_id   = topology_id;
+		} else {
+			cpu_topology[cpu].thread_id  = -1;
+			cpu_topology[cpu].core_id    = topology_id;
+		}
+		topology_id = find_acpi_cpu_topology_package(cpu);
+		cpu_topology[cpu].package_id = topology_id;
+	}
+
+	return 0;
+}
+
+#else
+static inline int __init parse_acpi_topology(void)
+{
+	return -EINVAL;
+}
+#endif
+
 void __init init_cpu_topology(void)
 {
 	reset_cpu_topology();
@@ -304,6 +345,8 @@  void __init init_cpu_topology(void)
 	 * Discard anything that was parsed if we hit an error so we
 	 * don't use partial information.
 	 */
-	if (of_have_populated_dt() && parse_dt_topology())
+	if ((!acpi_disabled) && parse_acpi_topology())
+		reset_cpu_topology();
+	else if (of_have_populated_dt() && parse_dt_topology())
 		reset_cpu_topology();
 }