kevin/linux
1
Fork 0
Code

RISC-V: Clean up the Zicbom block size probing

Browse Source 
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 <ajones@ventanamicro.com>
CC: Heiko Stuebner <heiko@sntech.de>
CC: Atish Patra <atishp@rivosinc.com>
Fixes: 3aefb2ee5b ("riscv: implement Zicbom-based CMO instructions + the t-head variant")
Fixes: 1631ba1259 ("riscv: Add support for non-coherent devices using zicbom extension")
Reported-by: kernel test robot <lkp@intel.com>
Reported-by: Conor Dooley <conor.dooley@microchip.com>
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
[Conor: fixed the redefinition errors]
Tested-by: Conor Dooley <conor.dooley@microchip.com>
Signed-off-by: Conor Dooley <conor.dooley@microchip.com>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20220912224800.998121-1-mail@conchuod.ie
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
This commit is contained in:
Palmer Dabbelt 2022-09-12 23:48:01 +01:00
parent 20e0fbab16
commit 8f7e001e03
No known key found for this signature in database
GPG Key ID: 2E1319F35FBB1889
4 changed files with 16 additions and 11 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
arch/riscv/errata/thead/errata.c
View File

@ -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

1
arch/riscv/include/asm/cacheflush.h
View File

@ -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) { }

2
arch/riscv/kernel/setup.c
View File

@ -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();
}

23
arch/riscv/mm/dma-noncoherent.c
View File

@ -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;
}