Re: [PATCH v2] powerpc/kernel/sysfs: Add PMU_SYSFS config option to enable PMU SPRs sysfs file creation

[maddy]

On 11/13/19 9:40 PM, Kajol Jain wrote:

Many of the performance moniroting unit (PMU) SPRs are
exposed in the sysfs. "perf" API is the primary interface to program
PMU and collect counter data in the system. So expose these
PMU SPRs in the absence of CONFIG_PERF_EVENTS.

Patch adds a new CONFIG option 'CONFIG_PMU_SYSFS'. The new config
option used in kernel/sysfs.c for PMU SPRs sysfs file creation and
this new option is enabled only if 'CONFIG_PERF_EVENTS' option is
disabled.

Tested this patch with enable/disable CONFIG_PERF_EVENTS option
in powernv and pseries machines.
Also did compilation testing for different architecture include:
x86, mips, mips64, alpha, arm. And with book3s_32.config option.

Reviewed-By: Madhavan Srinivasan <ma...@linux.vnet.ibm.com>

Signed-off-by: Kajol Jain <kj...@linux.ibm.com>
---
  arch/powerpc/kernel/sysfs.c            | 21 +++++++++++++++++++++
  arch/powerpc/platforms/Kconfig.cputype |  8 ++++++++
  2 files changed, 29 insertions(+)

---
Changelog:
v1 -> v2
- Added new config option 'PMU_SYSFS' for PMU SPR's creation
   rather than using PERF_EVENTS config option directly and make
   sure SPR's file creation only if 'CONFIG_PERF_EVENTS' disabled.
---
diff --git a/arch/powerpc/kernel/sysfs.c b/arch/powerpc/kernel/sysfs.c
index 80a676da11cb..b7c01f1ef236 100644
--- a/arch/powerpc/kernel/sysfs.c
+++ b/arch/powerpc/kernel/sysfs.c
@@ -457,16 +457,21 @@ static ssize_t __used \

  #if defined(CONFIG_PPC64)
  #define HAS_PPC_PMC_CLASSIC   1
+#ifdef CONFIG_PMU_SYSFS
  #define HAS_PPC_PMC_IBM               1
+#endif
  #define HAS_PPC_PMC_PA6T      1
  #elif defined(CONFIG_PPC_BOOK3S_32)
  #define HAS_PPC_PMC_CLASSIC   1
+#ifdef CONFIG_PMU_SYSFS
  #define HAS_PPC_PMC_IBM               1
  #define HAS_PPC_PMC_G4                1
  #endif
+#endif


  #ifdef HAS_PPC_PMC_CLASSIC
+#ifdef CONFIG_PMU_SYSFS
  SYSFS_PMCSETUP(mmcr0, SPRN_MMCR0);
  SYSFS_PMCSETUP(mmcr1, SPRN_MMCR1);
  SYSFS_PMCSETUP(pmc1, SPRN_PMC1);
@@ -485,6 +490,10 @@ SYSFS_PMCSETUP(pmc7, SPRN_PMC7);
  SYSFS_PMCSETUP(pmc8, SPRN_PMC8);

  SYSFS_PMCSETUP(mmcra, SPRN_MMCRA);
+#endif /* CONFIG_PPC64 */
+#endif /* CONFIG_PMU_SYSFS */
+
+#ifdef CONFIG_PPC64
  SYSFS_SPRSETUP(purr, SPRN_PURR);
  SYSFS_SPRSETUP(spurr, SPRN_SPURR);
  SYSFS_SPRSETUP(pir, SPRN_PIR);
@@ -495,7 +504,9 @@ SYSFS_SPRSETUP(tscr, SPRN_TSCR);
    enable write when needed with a separate function.
    Lets be conservative and default to pseries.
  */
+#ifdef CONFIG_PMU_SYSFS
  static DEVICE_ATTR(mmcra, 0600, show_mmcra, store_mmcra);
+#endif /* CONFIG_PMU_SYSFS */
  static DEVICE_ATTR(spurr, 0400, show_spurr, NULL);
  static DEVICE_ATTR(purr, 0400, show_purr, store_purr);
  static DEVICE_ATTR(pir, 0400, show_pir, NULL);
@@ -606,12 +617,14 @@ static void sysfs_create_dscr_default(void)
  #endif /* CONFIG_PPC64 */

  #ifdef HAS_PPC_PMC_PA6T
+#ifdef CONFIG_PMU_SYSFS
  SYSFS_PMCSETUP(pa6t_pmc0, SPRN_PA6T_PMC0);
  SYSFS_PMCSETUP(pa6t_pmc1, SPRN_PA6T_PMC1);
  SYSFS_PMCSETUP(pa6t_pmc2, SPRN_PA6T_PMC2);
  SYSFS_PMCSETUP(pa6t_pmc3, SPRN_PA6T_PMC3);
  SYSFS_PMCSETUP(pa6t_pmc4, SPRN_PA6T_PMC4);
  SYSFS_PMCSETUP(pa6t_pmc5, SPRN_PA6T_PMC5);
+#endif /* CONFIG_PMU_SYSFS */
  #ifdef CONFIG_DEBUG_MISC
  SYSFS_SPRSETUP(hid0, SPRN_HID0);
  SYSFS_SPRSETUP(hid1, SPRN_HID1);
@@ -644,6 +657,7 @@ SYSFS_SPRSETUP(tsr3, SPRN_PA6T_TSR3);
  #endif /* CONFIG_DEBUG_MISC */
  #endif /* HAS_PPC_PMC_PA6T */

+#ifdef CONFIG_PMU_SYSFS
  #ifdef HAS_PPC_PMC_IBM
  static struct device_attribute ibm_common_attrs[] = {
        __ATTR(mmcr0, 0600, show_mmcr0, store_mmcr0),
@@ -671,9 +685,11 @@ static struct device_attribute classic_pmc_attrs[] = {
        __ATTR(pmc8, 0600, show_pmc8, store_pmc8),
  #endif
  };
+#endif /* CONFIG_PMU_SYSFS */

  #ifdef HAS_PPC_PMC_PA6T
  static struct device_attribute pa6t_attrs[] = {
+#ifdef CONFIG_PMU_SYSFS
        __ATTR(mmcr0, 0600, show_mmcr0, store_mmcr0),
        __ATTR(mmcr1, 0600, show_mmcr1, store_mmcr1),
        __ATTR(pmc0, 0600, show_pa6t_pmc0, store_pa6t_pmc0),
@@ -682,6 +698,7 @@ static struct device_attribute pa6t_attrs[] = {
        __ATTR(pmc3, 0600, show_pa6t_pmc3, store_pa6t_pmc3),
        __ATTR(pmc4, 0600, show_pa6t_pmc4, store_pa6t_pmc4),
        __ATTR(pmc5, 0600, show_pa6t_pmc5, store_pa6t_pmc5),
+#endif /* CONFIG_PMU_SYSFS */
  #ifdef CONFIG_DEBUG_MISC
        __ATTR(hid0, 0600, show_hid0, store_hid0),
        __ATTR(hid1, 0600, show_hid1, store_hid1),
@@ -787,8 +804,10 @@ static int register_cpu_online(unsigned int cpu)
                        device_create_file(s, &pmc_attrs[i]);

  #ifdef CONFIG_PPC64
+#ifdef CONFIG_PMU_SYSFS
        if (cpu_has_feature(CPU_FTR_MMCRA))
                device_create_file(s, &dev_attr_mmcra);
+#endif /* CONFIG_PMU_SYSFS */

        if (cpu_has_feature(CPU_FTR_PURR)) {
                if (!firmware_has_feature(FW_FEATURE_LPAR))
@@ -876,8 +895,10 @@ static int unregister_cpu_online(unsigned int cpu)
                        device_remove_file(s, &pmc_attrs[i]);

  #ifdef CONFIG_PPC64
+#ifdef CONFIG_PMU_SYSFS
        if (cpu_has_feature(CPU_FTR_MMCRA))
                device_remove_file(s, &dev_attr_mmcra);
+#endif /* CONFIG_PMU_SYSFS */

        if (cpu_has_feature(CPU_FTR_PURR))
                device_remove_file(s, &dev_attr_purr);
diff --git a/arch/powerpc/platforms/Kconfig.cputype 
b/arch/powerpc/platforms/Kconfig.cputype
index 12543e53fa96..f3ad579c559f 100644
--- a/arch/powerpc/platforms/Kconfig.cputype
+++ b/arch/powerpc/platforms/Kconfig.cputype
@@ -417,6 +417,14 @@ config PPC_MM_SLICES
  config PPC_HAVE_PMU_SUPPORT
         bool

+config PMU_SYSFS
+       bool
+       default y if !PERF_EVENTS
+       help
+         This option enables PMU SPR sysfs file creation. Since PMU SPRs are
+         intended to be used via "perf" interface, config option is enabled
+         only when CONFIG_PERF_EVENTS is disabled.
+
  config PPC_PERF_CTRS
         def_bool y
         depends on PERF_EVENTS && PPC_HAVE_PMU_SUPPORT