Messages in this thread Patch in this message | | | Date | Mon, 4 Oct 2021 21:02:21 +0530 | Subject | Re: [PATCH 1/3] fixup mmu_features immediately after getting cpu pa features. | From | "Aneesh Kumar K.V" <> |
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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?
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();
> 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..9ed452605a2c 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 mmu_cpu_feature_fixup(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 >
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