kernel/arch/powerpc/platforms/pseries/lpar.c, branch linux-6.2.y

powerpc/pseries: Implement CONFIG_PARAVIRT_TIME_ACCOUNTING

2022-09-05T04:14:02Z

CONFIG_VIRT_CPU_ACCOUNTING_GEN under pseries does not provide stolen time accounting unless CONFIG_PARAVIRT_TIME_ACCOUNTING is enabled. Implement this using the VPA accumulated wait counters. Note this will not work on current KVM hosts because KVM does not implement the VPA dispatch counters (yet). It could be implemented with the dispatch trace log as it is for VIRT_CPU_ACCOUNTING_NATIVE, but that is not necessary for the more limited accounting provided by PARAVIRT_TIME_ACCOUNTING, and it is more expensive, complex, and has downsides like potential log wrap. From Shrikanth: [...] it was tested on Power10 [PowerVM] Shared LPAR. system has two LPAR. we will call first one LPAR1 and second one as LPAR2. Test was carried out in SMT=1. Similar observation was seen in SMT=8 as well. LPAR config header from each LPAR is below. LPAR1 is twice as big as LPAR2. Since Both are sharing the same underlying hardware, work stealing will happen when both the LPAR's are contending for the same resource. LPAR1: type=Shared mode=Uncapped smt=Off lcpu=40 cpus=40 ent=20.00 LPAR2: type=Shared mode=Uncapped smt=Off lcpu=20 cpus=40 ent=10.00 mpstat was used to check for the utilization. stress-ng has been used as the workload. Few cases are tested. when the both LPAR are idle there is no steal time. when LPAR1 starts running at 100% which consumes all of the physical resource, steal time starts to get accounted. With LPAR1 running at 100% and LPAR2 starts running, steal time starts increasing. This is as expected. When the LPAR2 Load is increased further, steal time increases further. Case 1: 0% LPAR1; 0% LPAR2 %usr %nice %sys %iowait %irq %soft %steal %guest %gnice %idle 0.00 0.00 0.05 0.00 0.00 0.00 0.00 0.00 0.00 99.95 Case 2: 100% LPAR1; 0% LPAR2 %usr %nice %sys %iowait %irq %soft %steal %guest %gnice %idle 97.68 0.00 0.00 0.00 0.00 0.00 2.32 0.00 0.00 0.00 Case 3: 100% LPAR1; 50% LPAR2 %usr %nice %sys %iowait %irq %soft %steal %guest %gnice %idle 86.34 0.00 0.10 0.00 0.00 0.03 13.54 0.00 0.00 0.00 Case 4: 100% LPAR1; 100% LPAR2 %usr %nice %sys %iowait %irq %soft %steal %guest %gnice %idle 78.54 0.00 0.07 0.00 0.00 0.02 21.36 0.00 0.00 0.00 Case 5: 50% LPAR1; 100% LPAR2 %usr %nice %sys %iowait %irq %soft %steal %guest %gnice %idle 49.37 0.00 0.00 0.00 0.00 0.00 1.17 0.00 0.00 49.47 Patch is accounting for the steal time and basic tests are holding good. Signed-off-by: Nicholas Piggin Tested-by: Shrikanth Hegde [mpe: Add SPDX tag to new paravirt_api_clock.h] Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20220902085316.2071519-3-npiggin@gmail.com

powerpc: Don't include asm/setup.h in asm/machdep.h

2022-06-20T01:29:49Z

asm/machdep.h doesn't need asm/setup.h Remove it. Add it directly in files that needs it. Signed-off-by: Christophe Leroy Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/3b1dfb19a2c3265fb4abc2bfc7b6eae9261a998b.1654966508.git.christophe.leroy@csgroup.eu

powerpc: Remove asm/prom.h from all files that don't need it

2022-05-08T12:15:04Z

Several files include asm/prom.h for no reason. Clean it up. Signed-off-by: Christophe Leroy [mpe: Drop change to prom_parse.c as reported by lkp@intel.com] Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/7c9b8fda63dcf63e1b28f43e7ebdb95182cbc286.1646767214.git.christophe.leroy@csgroup.eu

powerpc: Move C prototypes out of asm-prototypes.h

2022-03-08T11:06:25Z

We originally added asm-prototypes.h in commit 42f5b4cacd78 ("powerpc: Introduce asm-prototypes.h"). It's purpose was for prototypes of C functions that are only called from asm, in order to fix sparse warnings about missing prototypes. A few months later Nick added a different use case in commit 4efca4ed05cb ("kbuild: modversions for EXPORT_SYMBOL() for asm") for C prototypes for exported asm functions. This is basically the inverse of our original usage. Since then we've added various prototypes to asm-prototypes.h for both reasons, meaning we now need to unstitch it all. Dispatch prototypes of C functions into relevant headers and keep only the prototypes for functions defined in assembly. For the time being, leave prom_init() there because moving it into asm/prom.h or asm/setup.h conflicts with drivers/gpu/drm/nouveau/nvkm/subdev/bios/shadowrom.o This will be fixed later by untaggling asm/pci.h and asm/prom.h or by renaming the function in shadowrom.c Signed-off-by: Christophe Leroy Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/62d46904eca74042097acf4cb12c175e3067f3d1.1646413435.git.christophe.leroy@csgroup.eu

powerpc/pseries: Add __init attribute to eligible functions

2021-12-23T11:33:15Z

Some functions defined in 'arch/powerpc/platforms/pseries' are deserving of an `__init` macro attribute. These functions are only called by other initialization functions and therefore should inherit the attribute. Also, change function declarations in header files to include `__init`. Signed-off-by: Nick Child Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20211216220035.605465-13-nick.child@ibm.com

powerpc/64s: Move hash MMU support code under CONFIG_PPC_64S_HASH_MMU

2021-12-09T11:41:13Z

Compiling out hash support code when CONFIG_PPC_64S_HASH_MMU=n saves 128kB kernel image size (90kB text) on powernv_defconfig minus KVM, 350kB on pseries_defconfig minus KVM, 40kB on a tiny config. Signed-off-by: Nicholas Piggin [mpe: Fixup defined(ARCH_HAS_MEMREMAP_COMPAT_ALIGN), which needs CONFIG. Fix radix_enabled() use in setup_initial_memory_limit(). Add some stubs to reduce number of ifdefs.] Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20211201144153.2456614-18-npiggin@gmail.com

powerpc/pseries: move process table registration away from hash-specific code

2021-12-02T11:57:23Z

This reduces ifdefs in a later change which makes hash support configurable. Signed-off-by: Nicholas Piggin Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20211201144153.2456614-6-npiggin@gmail.com

powerpc/pseries: Add a helper for form1 cpu distance

2021-08-13T12:04:27Z

This helper is only used with the dispatch trace log collection. A later patch will add Form2 affinity support and this change helps in keeping that simpler. Also add a comment explaining we don't expect the code to be called with FORM0 Signed-off-by: Aneesh Kumar K.V Reviewed-by: David Gibson Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20210812132223.225214-5-aneesh.kumar@linux.ibm.com

powerpc: rename powerpc_debugfs_root to arch_debugfs_dir

2021-08-13T12:04:26Z

No functional change in this patch. arch_debugfs_dir is the generic kernel name declared in linux/debugfs.h for arch-specific debugfs directory. Architectures like x86/s390 already use the name. Rename powerpc specific powerpc_debugfs_root to arch_debugfs_dir. Signed-off-by: Aneesh Kumar K.V Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20210812132831.233794-2-aneesh.kumar@linux.ibm.com

powerpc/kexec: blacklist functions called in real mode for kprobe

2021-07-26T10:38:51Z

As kprobe does not handle events happening in real mode, blacklist the functions that only get called in real mode or in kexec sequence with MMU turned off. Signed-off-by: Hari Bathini Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/162626687834.155313.4692863392927831843.stgit@hbathini-workstation.ibm.com