Re: [PATCH v3 1/4] RISC-V: Fix compilation without RISCV_ISA_ZICBOM

[<Conor.Dooley@microchip.com>]

On 19/10/2022 13:30, Heiko Stuebner wrote:
> EXTERNAL EMAIL: Do not click links or open attachments unless you know the content is safe
> 
> Hi Anup,
> 
> Am Mittwoch, 19. Oktober 2022, 14:16:19 CEST schrieb Anup Patel:
>> From: Andrew Jones <ajones@ventanamicro.com>
>>
>> riscv_cbom_block_size and riscv_init_cbom_blocksize() should always
>> be available and riscv_init_cbom_blocksize() should always be
>> invoked, even when compiling without RISCV_ISA_ZICBOM enabled. This
>> is because disabling RISCV_ISA_ZICBOM means "don't use zicbom
>> instructions in the kernel" not "pretend there isn't zicbom, even
>> when there is". When zicbom is available, whether the kernel enables
>> its use with RISCV_ISA_ZICBOM or not, KVM will offer it to guests.
>> Ensure we can build KVM and that the block size is initialized even
>> when compiling without RISCV_ISA_ZICBOM.
> 
> either I'm way very low on coffee or something is strange here :-) .
> 
> I can fully grasp the need to init the cbom blocksize for guests, even when
> the main kernel isn't using it, but below in the patch itself it is still:
> 
> +#ifdef CONFIG_RISCV_ISA_ZICBOM
> +void riscv_init_cbom_blocksize(void)
> +{
> [...]
> 
> so the init_cbom_blocksize function is still inside a RISCV_ISA_ZICBOM
> ifdef?

FWIW:
Drew's patch, or at least the version of it that I have been using/did
a review of, does not have init_cbom_blocksize() inside such a #ifdef.

> 
> 
> Heiko
> 
> 
>>
>> Fixes: 8f7e001e0325 ("RISC-V: Clean up the Zicbom block size probing")
>> Reported-by: kernel test robot <lkp@intel.com>
>> Signed-off-by: Andrew Jones <ajones@ventanamicro.com>
>> Signed-off-by: Anup Patel <apatel@ventanamicro.com>
>> Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
>> ---
>>   arch/riscv/mm/cacheflush.c      | 41 +++++++++++++++++++++++++++++++++
>>   arch/riscv/mm/dma-noncoherent.c | 41 ---------------------------------
>>   2 files changed, 41 insertions(+), 41 deletions(-)
>>
>> diff --git a/arch/riscv/mm/cacheflush.c b/arch/riscv/mm/cacheflush.c
>> index 6cb7d96ad9c7..f318b2553612 100644
>> --- a/arch/riscv/mm/cacheflush.c
>> +++ b/arch/riscv/mm/cacheflush.c
>> @@ -3,6 +3,8 @@
>>    * Copyright (C) 2017 SiFive
>>    */
>>
>> +#include <linux/of.h>
>> +#include <linux/of_device.h>
>>   #include <asm/cacheflush.h>
>>
>>   #ifdef CONFIG_SMP
>> @@ -86,3 +88,42 @@ void flush_icache_pte(pte_t pte)
>>                flush_icache_all();
>>   }
>>   #endif /* CONFIG_MMU */
>> +
>> +unsigned int riscv_cbom_block_size;
>> +EXPORT_SYMBOL_GPL(riscv_cbom_block_size);
>> +
>> +#ifdef CONFIG_RISCV_ISA_ZICBOM
>> +void riscv_init_cbom_blocksize(void)
>> +{
>> +     struct device_node *node;
>> +     unsigned long cbom_hartid;
>> +     u32 val, probed_block_size;
>> +     int ret;
>> +
>> +     probed_block_size = 0;
>> +     for_each_of_cpu_node(node) {
>> +             unsigned long hartid;
>> +
>> +             ret = riscv_of_processor_hartid(node, &hartid);
>> +             if (ret)
>> +                     continue;
>> +
>> +             /* set block-size for cbom extension if available */
>> +             ret = of_property_read_u32(node, "riscv,cbom-block-size", &val);
>> +             if (ret)
>> +                     continue;
>> +
>> +             if (!probed_block_size) {
>> +                     probed_block_size = val;
>> +                     cbom_hartid = hartid;
>> +             } else {
>> +                     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
>> diff --git a/arch/riscv/mm/dma-noncoherent.c b/arch/riscv/mm/dma-noncoherent.c
>> index b0add983530a..d919efab6eba 100644
>> --- a/arch/riscv/mm/dma-noncoherent.c
>> +++ b/arch/riscv/mm/dma-noncoherent.c
>> @@ -8,13 +8,8 @@
>>   #include <linux/dma-direct.h>
>>   #include <linux/dma-map-ops.h>
>>   #include <linux/mm.h>
>> -#include <linux/of.h>
>> -#include <linux/of_device.h>
>>   #include <asm/cacheflush.h>
>>
>> -unsigned int riscv_cbom_block_size;
>> -EXPORT_SYMBOL_GPL(riscv_cbom_block_size);
>> -
>>   static bool noncoherent_supported;
>>
>>   void arch_sync_dma_for_device(phys_addr_t paddr, size_t size,
>> @@ -77,42 +72,6 @@ void arch_setup_dma_ops(struct device *dev, u64 dma_base, u64 size,
>>        dev->dma_coherent = coherent;
>>   }
>>
>> -#ifdef CONFIG_RISCV_ISA_ZICBOM
>> -void riscv_init_cbom_blocksize(void)
>> -{
>> -     struct device_node *node;
>> -     unsigned long cbom_hartid;
>> -     u32 val, probed_block_size;
>> -     int ret;
>> -
>> -     probed_block_size = 0;
>> -     for_each_of_cpu_node(node) {
>> -             unsigned long hartid;
>> -
>> -             ret = riscv_of_processor_hartid(node, &hartid);
>> -             if (ret)
>> -                     continue;
>> -
>> -             /* set block-size for cbom extension if available */
>> -             ret = of_property_read_u32(node, "riscv,cbom-block-size", &val);
>> -             if (ret)
>> -                     continue;
>> -
>> -             if (!probed_block_size) {
>> -                     probed_block_size = val;
>> -                     cbom_hartid = hartid;
>> -             } else {
>> -                     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,
>>
> 
> 
> 
> 
> 
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