Messages in this thread | | | Date | Tue, 5 Oct 2021 11:24:08 +0530 | From | Mahesh J Salgaonkar <> | Subject | Re: [PATCH 1/3] fixup mmu_features immediately after getting cpu pa features. |
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On 2021-10-04 21:02:21 Mon, Aneesh Kumar K.V wrote: > On 10/4/21 20:41, Sourabh Jain wrote: > > From: Mahesh Salgaonkar <mahesh@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. > > > > With 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 <mahesh@linux.ibm.com> > > Signed-off-by: Sourabh Jain <sourabhjain@linux.ibm.com> > > Reported-and-tested-by: Abdul haleem <abdhalee@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 | 1 + > > arch/powerpc/mm/init_64.c | 5 ++++- > > 4 files changed, 7 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..69a89fa1330d 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 mmu_cpu_feature_fixup(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..c8eafd401fe9 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 mmu_cpu_feature_fixup(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..1727a3abe6c1 100644 > > --- a/arch/powerpc/kernel/prom.c > > +++ b/arch/powerpc/kernel/prom.c > > @@ -380,6 +380,7 @@ static int __init early_init_dt_scan_cpus(unsigned long node, > > check_cpu_pa_features(node); > > } > > + mmu_cpu_feature_fixup(); > > can you do that call inside check_cpu_pa_features? or is it because we have > the same issue with baremetal platforms?
Yup same issue exist on baremetal as well in case of dt_cpu_ftrs_in_use is true. Hence calling it after the if (!dt_cpu_ftrs_in_use) code block takes care of both pseries and baremetal platforms.
> > Can we also rename this to indicate we are sanitizing the feature flag based > on kernel command line. Something like > > /* Update cpu features based on kernel command line */ > update_cpu_features();
Sure will do.
Thanks for your review. -Mahesh.
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