Messages in this thread | | | Date | Thu, 13 Apr 2023 11:20:05 +0100 | From | Sudeep Holla <> | Subject | Re: [PATCH v3 4/4] cacheinfo: Add use_arch[|_cache]_info field/function |
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On Thu, Apr 13, 2023 at 12:17:09PM +0200, Pierre Gondois wrote: > > > 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] >
Ah right, I missed to see that. I was sure there is a reason but couldn't figure out myself quickly.
> > > > > 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. >
Yes that would be good.
> > > > > 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. >
Sure.
-- Regards, Sudeep
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