kernel.git/arch/powerpc/mm, branch linux-rolling-stable

powerpc/64s/slb: Add no_slb_preload early cmdline param

2025-11-18T07:05:53Z

no_slb_preload cmdline can come useful in quickly disabling and/or testing the performance impact of userspace slb preloads. Recently there was a slb multi-hit issue due to slb preload cache which was very difficult to triage. This cmdline option allows to quickly disable preloads and verify if the issue exists in preload cache or somewhere else. This can also be a useful option to see the effect of slb preloads for any application workload e.g. number of slb faults with or w/o slb preloads. with slb_preload: slb_faults (minimal initrd boot): 15 slb_faults (full systemd boot): 300 with no_slb_preload: slb_faults (minimal initrd boot): 33 slb_faults (full systemd boot): 138180 Signed-off-by: Ritesh Harjani (IBM) Signed-off-by: Madhavan Srinivasan Link: https://patch.msgid.link/de484b55c45d831bc2db63945f455153c89a9a65.1761834163.git.ritesh.list@gmail.com

powerpc/64s/slb: Make preload_add return type as void

2025-11-18T07:05:53Z

We dropped preload_new_slb_context() & slb_setup_new_exec() in a previous patch. That means we don't really need preload_add() return type anymore. So let's make its return type as void. Signed-off-by: Ritesh Harjani (IBM) Signed-off-by: Madhavan Srinivasan Link: https://patch.msgid.link/88b07223e93b0fc56c1119f6889b7d9c83e20109.1761834163.git.ritesh.list@gmail.com

powerpc/ptdump: Dump PXX level info for kernel_page_tables

2025-11-18T07:05:53Z

This patch adds PGD/PUD/PMD/PTE level information while dumping kernel page tables. Before this patch it was hard to identify which entries belongs to which page table level e.g. ~ # dmesg |grep -i radix [0.000000] radix-mmu: Mapped 0x0000000000000000-0x0000000005400000 with 2.00 MiB pages (exec) [0.000000] radix-mmu: Mapped 0x0000000005400000-0x0000000040000000 with 2.00 MiB pages [0.000000] radix-mmu: Mapped 0x0000000040000000-0x0000000100000000 with 1.00 GiB pages [0.000000] radix-mmu: Initializing Radix MMU Before: ---[ Start of kernel VM ]--- 0xc000000000000000-0xc000000003ffffff XXX 64M r X pte valid present dirty accessed 0xc000000004000000-0xc00000003fffffff XXX 960M r w pte valid present dirty accessed 0xc000000040000000-0xc0000000ffffffff XXX 3G r w pte valid present dirty accessed ... ---[ vmemmap start ]--- 0xc00c000000000000-0xc00c0000003fffff XXX 4M r w pte valid present dirty accessed After: ---[ Start of kernel VM ]--- 0xc000000000000000-0xc000000003ffffff XXX 64M PMD r X pte valid present dirty accessed 0xc000000004000000-0xc00000003fffffff XXX 960M PMD r w pte valid present dirty accessed 0xc000000040000000-0xc0000000ffffffff XXX 3G PUD r w pte valid present dirty accessed ... ---[ vmemmap start ]--- 0xc00c000000000000-0xc00c0000003fffff XXX 4M PMD r w pte valid present dirty accessed Signed-off-by: Ritesh Harjani (IBM) Signed-off-by: Madhavan Srinivasan Link: https://patch.msgid.link/95defb675ee5607ef3923a1e6aeac39311b8fad4.1761834163.git.ritesh.list@gmail.com

powerpc/64s/pgtable: Enable directMap counters in meminfo for Hash

2025-11-18T07:05:53Z

This patch enables the directMap counters to be printed in proc/meminfo for Hash mmu. With this patch on a system with 8G of DRAM we can see the entire RAM mapped with 16M pagesize: cat /proc/meminfo |grep -i direct DirectMap4k: 0 kB DirectMap64k: 0 kB DirectMap16M: 8388608 kB DirectMap16G: 0 kB Tested with devdax too: root@buildroot:/# ndctl create-namespace -r region0 -m devdax -s 2G { "dev":"namespace0.0", "mode":"devdax", "map":"dev", "size":"2032.00 MiB (2130.71 MB)", "uuid":"aa383ded-cd99-43a0-979f-5225467cfb40", "daxregion":{ "id":0, "size":"2032.00 MiB (2130.71 MB)", "align":16777216, "devices":[ { "chardev":"dax0.0", "size":"2032.00 MiB (2130.71 MB)", "target_node":0, "align":"16.00 MiB (16.78 MB)", "mode":"devdax" } ] }, "align":16777216 } root@buildroot:/# cat /proc/meminfo |grep -i direct DirectMap4k: 0 kB DirectMap64k: 0 kB DirectMap16M: 10485760 kB DirectMap16G: 0 kB root@buildroot:/# ndctl destroy-namespace -f all destroyed 1 namespace root@buildroot:/# cat /proc/meminfo |grep -i direct DirectMap4k: 0 kB DirectMap64k: 0 kB DirectMap16M: 8388608 kB DirectMap16G: 0 kB Signed-off-by: Ritesh Harjani (IBM) Signed-off-by: Madhavan Srinivasan Link: https://patch.msgid.link/ffe47912e17075649b6ce5b2ee5d7f3eb5352e0b.1761834163.git.ritesh.list@gmail.com

powerpc/64s/hash: Update directMap page counters for Hash

2025-11-18T07:05:53Z

Update the directMap page counters for Hash. Hash by default always uses mmu_linear_psize only, for it's directMap. However, once the kernel has booted and the dmesg log is wrapped over there is no way of knowing the kernel linear pagesize with Hash mmu. Features like debug_page_alloc can make mmu_linear_psize to be PAGE_SIZE instead of PMD / PUD mappings. It would be easier if we have this info printed in proc meminfo similar to Radix for debugging purposes. Signed-off-by: Ritesh Harjani (IBM) Signed-off-by: Madhavan Srinivasan Link: https://patch.msgid.link/208e6f946d2ba9c1e2b8b4f665728abe5c891e7c.1761834163.git.ritesh.list@gmail.com

powerpc/64s/hash: Hash hpt_order should be only available with Hash MMU

2025-11-18T07:05:52Z

This disables creating hpt_order debugfs entry with radix mode. Signed-off-by: Ritesh Harjani (IBM) Signed-off-by: Madhavan Srinivasan Link: https://patch.msgid.link/99237176a51c73e85f4a7edd60a2460017882d69.1761834163.git.ritesh.list@gmail.com

powerpc/64s/hash: Improve hash mmu printk messages

2025-11-18T07:05:52Z

Let's use pr_info() instead of printk() in order to utilize the pr_fmt set to "hash-mmu:". This improves the debug messages that are spitted out during kernel bootup. Signed-off-by: Ritesh Harjani (IBM) Signed-off-by: Madhavan Srinivasan Link: https://patch.msgid.link/a2af842f85c099cdbd19bf468606960c5226a079.1761834163.git.ritesh.list@gmail.com

powerpc/64s/hash: Fix phys_addr_t printf format in htab_initialize()

2025-11-18T07:05:52Z

We get below errors when we try to enable debug logs in book3s64/hash_utils.c This patch fixes these errors related to phys_addr_t printf format. arch/powerpc/mm/book3s64/hash_utils.c: In function ‘htab_initialize’: arch/powerpc/mm/book3s64/hash_utils.c:1401:21: error: format ‘%lx’ expects argument of type ‘long unsigned int’, but argument 2 has type ‘phys_addr_t’ {aka ‘long long unsigned int’} [-Werror=format=] 1401 | DBG("creating mapping for region: %lx..%lx (prot: %lx)\n", arch/powerpc/mm/book3s64/hash_utils.c:1401:21: error: format ‘%lx’ expects argument of type ‘long unsigned int’, but argument 3 has type ‘phys_addr_t’ {aka ‘long long unsigned int’} [-Werror=format=] cc1: all warnings being treated as errors make[6]: *** [../scripts/Makefile.build:287: arch/powerpc/mm/book3s64/hash_utils.o] Error 1 Signed-off-by: Ritesh Harjani (IBM) Signed-off-by: Madhavan Srinivasan Link: https://patch.msgid.link/4873e9692fc4411099c9741005d218d5e734c345.1761834163.git.ritesh.list@gmail.com

powerpc/64s/ptdump: Fix kernel_hash_pagetable dump for ISA v3.00 HPTE format

2025-11-18T07:05:52Z

HPTE format was changed since Power9 (ISA 3.0) onwards. While dumping kernel hash page tables, nothing gets printed on powernv P9+. This patch utilizes the helpers added in the patch tagged as fixes, to convert new format to old format and dump the hptes. This fix is only needed for native_find() (powernv), since pseries continues to work fine with the old format. Fixes: 6b243fcfb5f1e ("powerpc/64: Simplify adaptation to new ISA v3.00 HPTE format") Signed-off-by: Ritesh Harjani (IBM) Signed-off-by: Madhavan Srinivasan Link: https://patch.msgid.link/4c2bb9e5b3cfbc0dd80b61b67cdd3ccfc632684c.1761834163.git.ritesh.list@gmail.com

powerpc/64s/hash: Restrict stress_hpt_struct memblock region to within RMA limit

2025-11-18T07:05:52Z

When HV=0 & IR/DR=0, the Hash MMU is said to be in Virtual Real Addressing Mode during early boot. During this, we should ensure that memory region allocations for stress_hpt_struct should happen from within RMA region as otherwise the boot might get stuck while doing memset of this region. History behind why do we have RMA region limitation is better explained in these 2 patches [1] & [2]. This patch ensures that memset to stress_hpt_struct during early boot does not cross ppc64_rma_size boundary. [1]: https://lore.kernel.org/all/20190710052018.14628-1-sjitindarsingh@gmail.com/ [2]: https://lore.kernel.org/all/87wp54usvj.fsf@linux.vnet.ibm.com/ Fixes: 6b34a099faa12 ("powerpc/64s/hash: add stress_hpt kernel boot option to increase hash faults") Signed-off-by: Ritesh Harjani (IBM) Signed-off-by: Madhavan Srinivasan Link: https://patch.msgid.link/ada1173933ea7617a994d6ee3e54ced8797339fc.1761834163.git.ritesh.list@gmail.com