From 8f7e001e0325de63a42f23342ac3b8139150c5cf Mon Sep 17 00:00:00 2001 From: Palmer Dabbelt Date: Mon, 12 Sep 2022 23:48:01 +0100 Subject: [PATCH] RISC-V: Clean up the Zicbom block size probing This fixes two issues: I truncated the warning's hart ID when porting to the 64-bit hart ID code, and the original code's warning handling could fire on an uninitialized hart ID. The biggest change here is that riscv_cbom_block_size is no longer initialized, as IMO the default isn't sane: there's nothing in the ISA that mandates any specific cache block size, so falling back to one will just silently produce the wrong answer on some systems. This also changes the probing order so the cache block size is known before enabling Zicbom support. CC: stable@vger.kernel.org CC: Andrew Jones CC: Heiko Stuebner CC: Atish Patra Fixes: 3aefb2ee5bdd ("riscv: implement Zicbom-based CMO instructions + the t-head variant") Fixes: 1631ba1259d6 ("riscv: Add support for non-coherent devices using zicbom extension") Reported-by: kernel test robot Reported-by: Conor Dooley Signed-off-by: Palmer Dabbelt [Conor: fixed the redefinition errors] Tested-by: Conor Dooley Signed-off-by: Conor Dooley Cc: stable@vger.kernel.org Link: https://lore.kernel.org/r/20220912224800.998121-1-mail@conchuod.ie Signed-off-by: Palmer Dabbelt --- arch/riscv/errata/thead/errata.c | 1 + arch/riscv/include/asm/cacheflush.h | 1 + arch/riscv/kernel/setup.c | 2 +- arch/riscv/mm/dma-noncoherent.c | 23 +++++++++++++---------- 4 files changed, 16 insertions(+), 11 deletions(-) diff --git a/arch/riscv/errata/thead/errata.c b/arch/riscv/errata/thead/errata.c index 202c83f..96648c1 100644 --- a/arch/riscv/errata/thead/errata.c +++ b/arch/riscv/errata/thead/errata.c @@ -37,6 +37,7 @@ static bool errata_probe_cmo(unsigned int stage, if (stage == RISCV_ALTERNATIVES_EARLY_BOOT) return false; + riscv_cbom_block_size = L1_CACHE_BYTES; riscv_noncoherent_supported(); return true; #else diff --git a/arch/riscv/include/asm/cacheflush.h b/arch/riscv/include/asm/cacheflush.h index a60acae..a89c005 100644 --- a/arch/riscv/include/asm/cacheflush.h +++ b/arch/riscv/include/asm/cacheflush.h @@ -43,6 +43,7 @@ void flush_icache_mm(struct mm_struct *mm, bool local); #endif /* CONFIG_SMP */ #ifdef CONFIG_RISCV_ISA_ZICBOM +extern unsigned int riscv_cbom_block_size; void riscv_init_cbom_blocksize(void); #else static inline void riscv_init_cbom_blocksize(void) { } diff --git a/arch/riscv/kernel/setup.c b/arch/riscv/kernel/setup.c index 95ef6e2..2dfc463 100644 --- a/arch/riscv/kernel/setup.c +++ b/arch/riscv/kernel/setup.c @@ -296,8 +296,8 @@ void __init setup_arch(char **cmdline_p) setup_smp(); #endif - riscv_fill_hwcap(); riscv_init_cbom_blocksize(); + riscv_fill_hwcap(); apply_boot_alternatives(); } diff --git a/arch/riscv/mm/dma-noncoherent.c b/arch/riscv/mm/dma-noncoherent.c index cd22253..e3f9bdf 100644 --- a/arch/riscv/mm/dma-noncoherent.c +++ b/arch/riscv/mm/dma-noncoherent.c @@ -12,7 +12,7 @@ #include #include -static unsigned int riscv_cbom_block_size = L1_CACHE_BYTES; +unsigned int riscv_cbom_block_size; static bool noncoherent_supported; void arch_sync_dma_for_device(phys_addr_t paddr, size_t size, @@ -79,38 +79,41 @@ void arch_setup_dma_ops(struct device *dev, u64 dma_base, u64 size, void riscv_init_cbom_blocksize(void) { struct device_node *node; + unsigned long cbom_hartid; + u32 val, probed_block_size; int ret; - u32 val; + probed_block_size = 0; for_each_of_cpu_node(node) { unsigned long hartid; - int cbom_hartid; ret = riscv_of_processor_hartid(node, &hartid); if (ret) continue; - if (hartid < 0) - continue; - /* set block-size for cbom extension if available */ ret = of_property_read_u32(node, "riscv,cbom-block-size", &val); if (ret) continue; - if (!riscv_cbom_block_size) { - riscv_cbom_block_size = val; + if (!probed_block_size) { + probed_block_size = val; cbom_hartid = hartid; } else { - if (riscv_cbom_block_size != val) - pr_warn("cbom-block-size mismatched between harts %d and %lu\n", + if (probed_block_size != val) + pr_warn("cbom-block-size mismatched between harts %lu and %lu\n", cbom_hartid, hartid); } } + + if (probed_block_size) + riscv_cbom_block_size = probed_block_size; } #endif void riscv_noncoherent_supported(void) { + WARN(!riscv_cbom_block_size, + "Non-coherent DMA support enabled without a block size\n"); noncoherent_supported = true; } -- 2.7.4