Messages in this thread | | | Date | Thu, 13 Apr 2023 12:17:09 +0200 | Subject | Re: [PATCH v3 4/4] cacheinfo: Add use_arch[|_cache]_info field/function | From | Pierre Gondois <> |
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On 4/13/23 11:49, Sudeep Holla wrote: > On Thu, Apr 13, 2023 at 11:14:34AM +0200, Pierre Gondois wrote: >> The cache information can be extracted from either a Device >> Tree (DT), the PPTT ACPI table, or arch registers (clidr_el1 >> for arm64). >> >> The clidr_el1 register is used only if DT/ACPI information is not >> available. It does not states how caches are shared among CPUs. >> >> Add a use_arch_cache_info field/function to identify when the >> DT/ACPI doesn't provide cache information. Use this information >> to assume L1 caches are privates and L2 and higher are shared among >> all CPUs. >> > > I have tentatively merged first 3 patches along with Radu's series(waiting > for build tests still before confirming). I am not yet sure on this. > >> Signed-off-by: Pierre Gondois <pierre.gondois@arm.com> >> --- >> drivers/base/cacheinfo.c | 13 ++++++++++++- >> include/linux/cacheinfo.h | 10 ++++++++++ >> 2 files changed, 22 insertions(+), 1 deletion(-) >> >> diff --git a/drivers/base/cacheinfo.c b/drivers/base/cacheinfo.c >> index 06de9a468958..49dbb4357911 100644 >> --- a/drivers/base/cacheinfo.c >> +++ b/drivers/base/cacheinfo.c >> @@ -40,7 +40,8 @@ static inline bool cache_leaves_are_shared(struct cacheinfo *this_leaf, >> * For non DT/ACPI systems, assume unique level 1 caches, >> * system-wide shared caches for all other levels. >> */ >> - if (!(IS_ENABLED(CONFIG_OF) || IS_ENABLED(CONFIG_ACPI))) >> + if (!(IS_ENABLED(CONFIG_OF) || IS_ENABLED(CONFIG_ACPI)) || >> + this_leaf->use_arch_info) > > Can't we just use use_arch_cache_info() here ?
I think that if we use use_arch_cache_info() here, then arm64 platforms will always return here and never check fw_token/this_leaf->id values. Indeed, we also need to know that no cache information is available in DT/ACPI, cf. [1]
> >> return (this_leaf->level != 1) && (sib_leaf->level != 1); >> >> if ((sib_leaf->attributes & CACHE_ID) && >> @@ -349,6 +350,7 @@ static int cache_shared_cpu_map_setup(unsigned int cpu) >> struct cpu_cacheinfo *this_cpu_ci = get_cpu_cacheinfo(cpu); >> struct cacheinfo *this_leaf, *sib_leaf; >> unsigned int index, sib_index; >> + bool use_arch_info = false; >> int ret = 0; >> >> if (this_cpu_ci->cpu_map_populated) >> @@ -361,6 +363,12 @@ static int cache_shared_cpu_map_setup(unsigned int cpu) >> */ >> if (!last_level_cache_is_valid(cpu)) { >> ret = cache_setup_properties(cpu); >> + if (ret && use_arch_cache_info()) { >> + // Possibility to rely on arch specific information.
[1]
>> + use_arch_info = true; >> + ret = 0; >> + } >> + >> if (ret) >> return ret; >> } >> @@ -370,6 +378,9 @@ static int cache_shared_cpu_map_setup(unsigned int cpu) >> >> this_leaf = per_cpu_cacheinfo_idx(cpu, index); >> >> + if (use_arch_info) >> + this_leaf->use_arch_info = true; >> + >> cpumask_set_cpu(cpu, &this_leaf->shared_cpu_map); >> for_each_online_cpu(i) { >> struct cpu_cacheinfo *sib_cpu_ci = get_cpu_cacheinfo(i); >> diff --git a/include/linux/cacheinfo.h b/include/linux/cacheinfo.h >> index 908e19d17f49..fed675b251a2 100644 >> --- a/include/linux/cacheinfo.h >> +++ b/include/linux/cacheinfo.h >> @@ -66,6 +66,7 @@ struct cacheinfo { >> #define CACHE_ALLOCATE_POLICY_MASK \ >> (CACHE_READ_ALLOCATE | CACHE_WRITE_ALLOCATE) >> #define CACHE_ID BIT(4) >> + bool use_arch_info; > > Do you see the need to stash this value as it is either globally true or > false based on the arch ?
A static variable could be used instead and set to true if we fail to fetch the cache information from DT/ACPI, cf. [1]. The only possible transition for this variable would be from false->true. I'll check if this works like this.
> >> void *fw_token; >> bool disable_sysfs; >> void *priv; >> @@ -129,4 +130,13 @@ static inline int get_cpu_cacheinfo_id(int cpu, int level) >> return -1; >> } >> >> +static inline bool use_arch_cache_info(void) >> +{ >> +#if defined(CONFIG_ARM64) >> + return true; >> +#else >> + return false; >> +#endif >> +} >> + > > Can we just have it as: > #ifdef CONFIG_ARM64 > #define use_arch_cache_info() (true) > #else > #define use_arch_cache_info() (false) > #endif
Yes sure, I'll post a v4 with this along Conor's requested change.
> >> #endif /* _LINUX_CACHEINFO_H */ >> -- >> 2.25.1 >> >
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