On Mon, Sep 12, 2022 at 11:48:01PM +0100, Conor Dooley wrote:
> From: Palmer Dabbelt <palmer@xxxxxxxxxxxx>
>
> 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@xxxxxxxxxxxxxxx
> CC: Andrew Jones <ajones@xxxxxxxxxxxxxxxx>
> CC: Heiko Stuebner <heiko@xxxxxxxxx>
> CC: Atish Patra <atishp@xxxxxxxxxxxx>
> 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 <lkp@xxxxxxxxx>
> Reported-by: Conor Dooley <conor.dooley@xxxxxxxxxxxxx>
> Signed-off-by: Palmer Dabbelt <palmer@xxxxxxxxxxxx>
> [Conor: fixed the redefinition errors]
> Tested-by: Conor Dooley <conor.dooley@xxxxxxxxxxxxx>
> Signed-off-by: Conor Dooley <conor.dooley@xxxxxxxxxxxxx>
Build-tested-by: Nathan Chancellor <nathan@xxxxxxxxxx>
Thanks a lot for continuing to chase this!
> ---
> Hey Palmer,
> w/ LPC etc I figure it's highly unlikely you'd have this respun
> in time to have it applied this week. I dropped all the tested
> and reviewed -by tags since this patch has been changed a fair
> bit back and forth since the tags were left. Checked it on my
> D1 to make sure nothing blew up.. if this could make this weeks
> rc, that'd be great so that the clang allmodconfig builds are
> working again.
> Conor.
> ---
> 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 202c83f677b2..96648c176f37 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 a60acaecfeda..a89c005b4bbf 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 95ef6e2bf45c..2dfc463b86bb 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 cd2225304c82..e3f9bdf47c5f 100644
> --- a/arch/riscv/mm/dma-noncoherent.c
> +++ b/arch/riscv/mm/dma-noncoherent.c
> @@ -12,7 +12,7 @@
> #include <linux/of_device.h>
> #include <asm/cacheflush.h>
>
> -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;
> }
> --
> 2.37.1
>
