From: Mahesh Salgaonkar <mah...@linux.ibm.com> On system with radix support available, early_radix_enabled() starts returning true for a small window (until mmu_early_init_devtree() is called) even when radix mode disabled on kernel command line. This causes ppc64_bolted_size() to return ULONG_MAX in HPT mode instead of supported segment size, during boot cpu paca allocation.
Withi kernel command line = "... disable_radix": early_init_devtree: <- early_radix_enabled() = false early_init_dt_scan_cpus: <- early_radix_enabled() = false ... check_cpu_pa_features: <- early_radix_enabled() = false ... ^ <- early_radix_enabled() = TRUE allocate_paca: | <- early_radix_enabled() = TRUE ... | ppc64_bolted_size: | <- early_radix_enabled() = TRUE if (early_radix_enabled())| <- early_radix_enabled() = TRUE return ULONG_MAX; | ... | ... | <- early_radix_enabled() = TRUE ... | <- early_radix_enabled() = TRUE mmu_early_init_devtree() V ... <- early_radix_enabled() = false So far we have not seen any issue because allocate_paca() takes minimum of ppc64_bolted_size and rma_size while allocating paca. However it is better to close this window by fixing up the mmu features as early as possible. This fixes early_radix_enabled() and ppc64_bolted_size() to return valid values in radix disable mode. This patch will help subsequent patch to depend on early_radix_enabled() check while detecting supported segment size in HPT mode. Signed-off-by: Mahesh Salgaonkar <mah...@linux.ibm.com> Signed-off-by: Sourabh Jain <sourabhj...@linux.ibm.com> Reported-and-tested-by: Abdul haleem <abdha...@linux.vnet.ibm.com> --- arch/powerpc/include/asm/book3s/64/mmu.h | 1 + arch/powerpc/include/asm/mmu.h | 1 + arch/powerpc/kernel/prom.c | 2 ++ arch/powerpc/mm/init_64.c | 5 ++++- 4 files changed, 8 insertions(+), 1 deletion(-) diff --git a/arch/powerpc/include/asm/book3s/64/mmu.h b/arch/powerpc/include/asm/book3s/64/mmu.h index c02f42d1031e..d60be5051d60 100644 --- a/arch/powerpc/include/asm/book3s/64/mmu.h +++ b/arch/powerpc/include/asm/book3s/64/mmu.h @@ -197,6 +197,7 @@ extern int mmu_vmemmap_psize; extern int mmu_io_psize; /* MMU initialization */ +void update_cpu_features(void); void mmu_early_init_devtree(void); void hash__early_init_devtree(void); void radix__early_init_devtree(void); diff --git a/arch/powerpc/include/asm/mmu.h b/arch/powerpc/include/asm/mmu.h index 8abe8e42e045..5eb494ea85d7 100644 --- a/arch/powerpc/include/asm/mmu.h +++ b/arch/powerpc/include/asm/mmu.h @@ -401,6 +401,7 @@ extern void early_init_mmu(void); extern void early_init_mmu_secondary(void); extern void setup_initial_memory_limit(phys_addr_t first_memblock_base, phys_addr_t first_memblock_size); +static inline void update_cpu_features(void) { } static inline void mmu_early_init_devtree(void) { } static inline void pkey_early_init_devtree(void) {} diff --git a/arch/powerpc/kernel/prom.c b/arch/powerpc/kernel/prom.c index 2e67588f6f6e..889c909e4ed4 100644 --- a/arch/powerpc/kernel/prom.c +++ b/arch/powerpc/kernel/prom.c @@ -380,6 +380,8 @@ static int __init early_init_dt_scan_cpus(unsigned long node, check_cpu_pa_features(node); } + /* Update cpu features based on kernel command line */ + update_cpu_features(); identical_pvr_fixup(node); init_mmu_slb_size(node); diff --git a/arch/powerpc/mm/init_64.c b/arch/powerpc/mm/init_64.c index 386be136026e..19680b42898f 100644 --- a/arch/powerpc/mm/init_64.c +++ b/arch/powerpc/mm/init_64.c @@ -437,12 +437,15 @@ static void __init early_check_vec5(void) } } -void __init mmu_early_init_devtree(void) +void __init update_cpu_features(void) { /* Disable radix mode based on kernel command line. */ if (disable_radix) cur_cpu_spec->mmu_features &= ~MMU_FTR_TYPE_RADIX; +} +void __init mmu_early_init_devtree(void) +{ /* * Check /chosen/ibm,architecture-vec-5 if running as a guest. * When running bare-metal, we can use radix if we like -- 2.31.1