From: Samuel Holland Date: Wed, 27 Mar 2024 04:49:49 +0000 (-0700) Subject: riscv: Avoid TLB flush loops when affected by SiFive CIP-1200 X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=d6dcdabafcd7c612b164079d00da6d9775863a0b;p=linux.git riscv: Avoid TLB flush loops when affected by SiFive CIP-1200 Implementations affected by SiFive errata CIP-1200 have a bug which forces the kernel to always use the global variant of the sfence.vma instruction. When affected by this errata, do not attempt to flush a range of addresses; each iteration of the loop would actually flush the whole TLB instead. Instead, minimize the overall number of sfence.vma instructions. Signed-off-by: Samuel Holland Reviewed-by: Yunhui Cui Link: https://lore.kernel.org/r/20240327045035.368512-9-samuel.holland@sifive.com Signed-off-by: Palmer Dabbelt --- diff --git a/arch/riscv/errata/sifive/errata.c b/arch/riscv/errata/sifive/errata.c index 3d9a32d791f73..716cfedad3a2a 100644 --- a/arch/riscv/errata/sifive/errata.c +++ b/arch/riscv/errata/sifive/errata.c @@ -42,6 +42,11 @@ static bool errata_cip_1200_check_func(unsigned long arch_id, unsigned long imp return false; if ((impid & 0xffffff) > 0x200630 || impid == 0x1200626) return false; + +#ifdef CONFIG_MMU + tlb_flush_all_threshold = 0; +#endif + return true; } diff --git a/arch/riscv/include/asm/tlbflush.h b/arch/riscv/include/asm/tlbflush.h index 463b615d7728c..8e329721375b3 100644 --- a/arch/riscv/include/asm/tlbflush.h +++ b/arch/riscv/include/asm/tlbflush.h @@ -66,6 +66,8 @@ void arch_tlbbatch_add_pending(struct arch_tlbflush_unmap_batch *batch, unsigned long uaddr); void arch_flush_tlb_batched_pending(struct mm_struct *mm); void arch_tlbbatch_flush(struct arch_tlbflush_unmap_batch *batch); + +extern unsigned long tlb_flush_all_threshold; #else /* CONFIG_MMU */ #define local_flush_tlb_all() do { } while (0) #endif /* CONFIG_MMU */ diff --git a/arch/riscv/mm/tlbflush.c b/arch/riscv/mm/tlbflush.c index ad7bdcfcc2199..18af7b5053af2 100644 --- a/arch/riscv/mm/tlbflush.c +++ b/arch/riscv/mm/tlbflush.c @@ -11,7 +11,7 @@ * Flush entire TLB if number of entries to be flushed is greater * than the threshold below. */ -static unsigned long tlb_flush_all_threshold __read_mostly = 64; +unsigned long tlb_flush_all_threshold __read_mostly = 64; static void local_flush_tlb_range_threshold_asid(unsigned long start, unsigned long size,