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Miller" , Helge Deller , Geert Uytterhoeven , Paul Burton , Tony Luck , Richard Henderson , Nick Hu , Paul Walmsley Subject: Re: [PATCH 05/17] asm-generic/tlb: Rename HAVE_RCU_TABLE_NO_INVALIDATE Message-ID: <20191217085138.GN2871@hirez.programming.kicks-ass.net> References: <20191211120713.360281197@infradead.org> <20191211122955.940455408@infradead.org> <87woawzc1t.fsf@linux.ibm.com> <20191216123752.GM2844@hirez.programming.kicks-ass.net> <20191216132004.GO2844@hirez.programming.kicks-ass.net> <33ed03aa-a34c-3a81-0f83-20c3e8d4eff7@linux.ibm.com> <20191216145041.GG2827@hirez.programming.kicks-ass.net> <20191216151419.GL2871@hirez.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20191216151419.GL2871@hirez.programming.kicks-ass.net> User-Agent: Mutt/1.10.1 (2018-07-13) X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Mon, Dec 16, 2019 at 04:14:19PM +0100, Peter Zijlstra wrote: > It seems to me you need something like this here patch, all you need to > add is a suitable definition of tlb_needs_table_invalidate() for Power. FWIW, Paul (Burton), MIPS should be able to have tlb_needs_table_invalidate() return false when it has pure software TLB fill. I tried to have a quick look for P5600 and P6600 to see if I could find the right state that indicates hardware TLB, but couldn't find anything. > --- > > diff --git a/arch/Kconfig b/arch/Kconfig > index c44ef15866a3..98de654b79b3 100644 > --- a/arch/Kconfig > +++ b/arch/Kconfig > @@ -400,10 +400,6 @@ config MMU_GATHER_RCU_TABLE_FREE > bool > select MMU_GATHER_TABLE_FREE > > -config MMU_GATHER_NO_TABLE_INVALIDATE > - bool > - depends on MMU_GATHER_RCU_TABLE_FREE > - > config MMU_GATHER_PAGE_SIZE > bool > > diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig > index 3dea4c8d39f2..2ddf24822d5b 100644 > --- a/arch/powerpc/Kconfig > +++ b/arch/powerpc/Kconfig > @@ -223,7 +223,6 @@ config PPC > select HAVE_PERF_REGS > select HAVE_PERF_USER_STACK_DUMP > select MMU_GATHER_RCU_TABLE_FREE if SMP > - select MMU_GATHER_NO_TABLE_INVALIDATE if MMU_GATHER_RCU_TABLE_FREE > select MMU_GATHER_PAGE_SIZE > select HAVE_REGS_AND_STACK_ACCESS_API > select HAVE_RELIABLE_STACKTRACE if PPC_BOOK3S_64 && CPU_LITTLE_ENDIAN > diff --git a/arch/sparc/Kconfig b/arch/sparc/Kconfig > index a76e915ab207..acf20b6c0a54 100644 > --- a/arch/sparc/Kconfig > +++ b/arch/sparc/Kconfig > @@ -66,7 +66,6 @@ config SPARC64 > select HAVE_KRETPROBES > select HAVE_KPROBES > select MMU_GATHER_RCU_TABLE_FREE if SMP > - select MMU_GATHER_NO_TABLE_INVALIDATE if MMU_GATHER_RCU_TABLE_FREE > select HAVE_MEMBLOCK_NODE_MAP > select HAVE_ARCH_TRANSPARENT_HUGEPAGE > select HAVE_DYNAMIC_FTRACE > diff --git a/arch/sparc/include/asm/tlb_64.h b/arch/sparc/include/asm/tlb_64.h > index a2f3fa61ee36..ac8e74a96122 100644 > --- a/arch/sparc/include/asm/tlb_64.h > +++ b/arch/sparc/include/asm/tlb_64.h > @@ -28,6 +28,12 @@ void flush_tlb_pending(void); > #define __tlb_remove_tlb_entry(tlb, ptep, address) do { } while (0) > #define tlb_flush(tlb) flush_tlb_pending() > > +/* > + * SPARC64's hardware TLB fill does not use the Linux page-tables > + * and therefore we don't need a TLBI when freeing page-table pages. > + */ > +#define tlb_needs_table_invalidate() (false) > + > #include > > #endif /* _SPARC64_TLB_H */ > diff --git a/include/asm-generic/tlb.h b/include/asm-generic/tlb.h > index fe0ea6ff3636..4108d6d18ca5 100644 > --- a/include/asm-generic/tlb.h > +++ b/include/asm-generic/tlb.h > @@ -156,13 +156,6 @@ > * Useful if your architecture doesn't use IPIs for remote TLB invalidates > * and therefore doesn't naturally serialize with software page-table walkers. > * > - * MMU_GATHER_NO_TABLE_INVALIDATE > - * > - * This makes MMU_GATHER_RCU_TABLE_FREE avoid calling tlb_flush_mmu_tlbonly() > - * before freeing the page-table pages. This can be avoided if you use > - * MMU_GATHER_RCU_TABLE_FREE and your architecture does _NOT_ use the Linux > - * page-tables natively. > - * > * MMU_GATHER_NO_RANGE > * > * Use this if your architecture lacks an efficient flush_tlb_range(). > @@ -203,6 +196,24 @@ extern void tlb_remove_table(struct mmu_gather *tlb, void *table); > > #endif /* CONFIG_MMU_GATHER_TABLE_FREE */ > > +#ifdef CONFIG_MMU_GATHER_RCU_TABLE_FREE > + > +/* > + * This allows an architecture that does not use the linux page-tables for > + * hardware to skip the TLBI when freeing page tables. > + */ > +#ifndef tlb_needs_table_invalidate > +#define tlb_needs_table_invalidate() (true) > +#endif > + > +#else > + > +#ifdef tlb_needs_table_invalidate > +#error tlb_needs_table_invalidate() requires MMU_GATHER_RCU_TABLE_FREE > +#endif > + > +#endif /* CONFIG_MMU_GATHER_RCU_TABLE_FREE */ > + > #ifndef CONFIG_MMU_GATHER_NO_GATHER > /* > * If we can't allocate a page to make a big batch of page pointers > diff --git a/mm/mmu_gather.c b/mm/mmu_gather.c > index 9d103031568d..a3538cb2bcbe 100644 > --- a/mm/mmu_gather.c > +++ b/mm/mmu_gather.c > @@ -177,14 +177,14 @@ static void tlb_remove_table_free(struct mmu_table_batch *batch) > */ > static inline void tlb_table_invalidate(struct mmu_gather *tlb) > { > -#ifndef CONFIG_MMU_GATHER_NO_TABLE_INVALIDATE > - /* > - * Invalidate page-table caches used by hardware walkers. Then we still > - * need to RCU-sched wait while freeing the pages because software > - * walkers can still be in-flight. > - */ > - tlb_flush_mmu_tlbonly(tlb); > -#endif > + if (tlb_needs_table_invalidate()) { > + /* > + * Invalidate page-table caches used by hardware walkers. Then > + * we still need to RCU-sched wait while freeing the pages > + * because software walkers can still be in-flight. > + */ > + tlb_flush_mmu_tlbonly(tlb); > + } > } > > static void tlb_remove_table_one(void *table)