From: Peter Zijlstra peterz@infradead.org Subject: mm/mmu_gather: invalidate TLB correctly on batch allocation failure and flush

Architectures for which we have hardware walkers of Linux page table should flush TLB on mmu gather batch allocation failures and batch flush. Some architectures like POWER supports multiple translation modes (hash and radix) and in the case of POWER only radix translation mode needs the above TLBI. This is because for hash translation mode kernel wants to avoid this extra flush since there are no hardware walkers of linux page table. With radix translation, the hardware also walks linux page table and with that, kernel needs to make sure to TLB invalidate page walk cache before page table pages are freed.

More details in commit d86564a2f085 ("mm/tlb, x86/mm: Support invalidating TLB caches for RCU_TABLE_FREE")

The changes to sparc are to make sure we keep the old behavior since we are now removing HAVE_RCU_TABLE_NO_INVALIDATE. The default value for tlb_needs_table_invalidate is to always force an invalidate and sparc can avoid the table invalidate. Hence we define tlb_needs_table_invalidate to false for sparc architecture.

Link: http://lkml.kernel.org/r/20200116064531.483522-3-aneesh.kumar@linux.ibm.com Fixes: a46cc7a90fd8 ("powerpc/mm/radix: Improve TLB/PWC flushes") Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org Signed-off-by: Aneesh Kumar K.V aneesh.kumar@linux.ibm.com Acked-by: Michael Ellerman mpe@ellerman.id.au [powerpc] Cc: stable@vger.kernel.org [4.14+] Signed-off-by: Andrew Morton akpm@linux-foundation.org ---

arch/Kconfig | 3 --- arch/powerpc/Kconfig | 1 - arch/powerpc/include/asm/tlb.h | 11 +++++++++++ arch/sparc/Kconfig | 1 - arch/sparc/include/asm/tlb_64.h | 9 +++++++++ include/asm-generic/tlb.h | 22 +++++++++++++++------- mm/mmu_gather.c | 16 ++++++++-------- 7 files changed, 43 insertions(+), 20 deletions(-)

--- a/arch/Kconfig~mm-mmu_gather-invalidate-tlb-correctly-on-batch-allocation-failure-and-flush +++ a/arch/Kconfig @@ -396,9 +396,6 @@ config HAVE_ARCH_JUMP_LABEL_RELATIVE config HAVE_RCU_TABLE_FREE bool

-config HAVE_RCU_TABLE_NO_INVALIDATE - bool - config HAVE_MMU_GATHER_PAGE_SIZE bool

--- a/arch/powerpc/include/asm/tlb.h~mm-mmu_gather-invalidate-tlb-correctly-on-batch-allocation-failure-and-flush +++ a/arch/powerpc/include/asm/tlb.h @@ -26,6 +26,17 @@

#define tlb_flush tlb_flush extern void tlb_flush(struct mmu_gather *tlb); +/* + * book3s: + * Hash does not use the linux page-tables, so we can avoid + * the TLB invalidate for page-table freeing, Radix otoh does use the + * page-tables and needs the TLBI. + * + * nohash: + * We still do TLB invalidate in the __pte_free_tlb routine before we + * add the page table pages to mmu gather table batch. + */ +#define tlb_needs_table_invalidate() radix_enabled()

/* Get the generic bits... */ #include <asm-generic/tlb.h> --- a/arch/powerpc/Kconfig~mm-mmu_gather-invalidate-tlb-correctly-on-batch-allocation-failure-and-flush +++ a/arch/powerpc/Kconfig @@ -223,7 +223,6 @@ config PPC select HAVE_PERF_REGS select HAVE_PERF_USER_STACK_DUMP select HAVE_RCU_TABLE_FREE - select HAVE_RCU_TABLE_NO_INVALIDATE if HAVE_RCU_TABLE_FREE select HAVE_MMU_GATHER_PAGE_SIZE select HAVE_REGS_AND_STACK_ACCESS_API select HAVE_RELIABLE_STACKTRACE if PPC_BOOK3S_64 && CPU_LITTLE_ENDIAN --- a/arch/sparc/include/asm/tlb_64.h~mm-mmu_gather-invalidate-tlb-correctly-on-batch-allocation-failure-and-flush +++ a/arch/sparc/include/asm/tlb_64.h @@ -28,6 +28,15 @@ 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. + */ + +#ifdef CONFIG_HAVE_RCU_TABLE_FREE +#define tlb_needs_table_invalidate() (false) +#endif + #include <asm-generic/tlb.h>

#endif /* _SPARC64_TLB_H */ --- a/arch/sparc/Kconfig~mm-mmu_gather-invalidate-tlb-correctly-on-batch-allocation-failure-and-flush +++ a/arch/sparc/Kconfig @@ -65,7 +65,6 @@ config SPARC64 select HAVE_KRETPROBES select HAVE_KPROBES select HAVE_RCU_TABLE_FREE if SMP - select HAVE_RCU_TABLE_NO_INVALIDATE if HAVE_RCU_TABLE_FREE select HAVE_MEMBLOCK_NODE_MAP select HAVE_ARCH_TRANSPARENT_HUGEPAGE select HAVE_DYNAMIC_FTRACE --- a/include/asm-generic/tlb.h~mm-mmu_gather-invalidate-tlb-correctly-on-batch-allocation-failure-and-flush +++ a/include/asm-generic/tlb.h @@ -137,13 +137,6 @@ * When used, an architecture is expected to provide __tlb_remove_table() * which does the actual freeing of these pages. * - * HAVE_RCU_TABLE_NO_INVALIDATE - * - * This makes HAVE_RCU_TABLE_FREE avoid calling tlb_flush_mmu_tlbonly() before - * freeing the page-table pages. This can be avoided if you use - * HAVE_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(). @@ -189,8 +182,23 @@ struct mmu_table_batch {

extern void tlb_remove_table(struct mmu_gather *tlb, void *table);

+/* + * 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 HAVE_RCU_TABLE_FREE +#endif + +#endif /* CONFIG_HAVE_RCU_TABLE_FREE */ + + #ifndef CONFIG_HAVE_MMU_GATHER_NO_GATHER /* * If we can't allocate a page to make a big batch of page pointers --- a/mm/mmu_gather.c~mm-mmu_gather-invalidate-tlb-correctly-on-batch-allocation-failure-and-flush +++ a/mm/mmu_gather.c @@ -102,14 +102,14 @@ bool __tlb_remove_page_size(struct mmu_g */ static inline void tlb_table_invalidate(struct mmu_gather *tlb) { -#ifndef CONFIG_HAVE_RCU_TABLE_NO_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_smp_sync(void *arg) _