Re: [PATCH v6 5/8] powerpc/pmem/of_pmem: Update of_pmem to use the new barrier instruction.
On Mon, Jun 29, 2020 at 10:05 PM Aneesh Kumar K.V wrote: > > Dan Williams writes: > > > On Mon, Jun 29, 2020 at 6:58 AM Aneesh Kumar K.V > > wrote: > >> > >> of_pmem on POWER10 can now use phwsync instead of hwsync to ensure > >> all previous writes are architecturally visible for the platform > >> buffer flush. > >> > >> Signed-off-by: Aneesh Kumar K.V > >> --- > >> arch/powerpc/include/asm/cacheflush.h | 7 +++ > >> 1 file changed, 7 insertions(+) > >> > >> diff --git a/arch/powerpc/include/asm/cacheflush.h > >> b/arch/powerpc/include/asm/cacheflush.h > >> index 54764c6e922d..95782f77d768 100644 > >> --- a/arch/powerpc/include/asm/cacheflush.h > >> +++ b/arch/powerpc/include/asm/cacheflush.h > >> @@ -98,6 +98,13 @@ static inline void invalidate_dcache_range(unsigned > >> long start, > >> mb(); /* sync */ > >> } > >> > >> +#define arch_pmem_flush_barrier arch_pmem_flush_barrier > >> +static inline void arch_pmem_flush_barrier(void) > >> +{ > >> + if (cpu_has_feature(CPU_FTR_ARCH_207S)) > >> + asm volatile(PPC_PHWSYNC ::: "memory"); > > > > Shouldn't this fallback to a compatible store-fence in an else statement? > > The idea was to avoid calling this on anything else. We ensure that by > making sure that pmem devices are not initialized on systems without that > cpu feature. Patch 1 does that. Also, the last patch adds a WARN_ON() to > catch the usage of this outside pmem devices and on systems without that > cpu feature. If patch1 handles this why re-check the cpu-feature in this helper? If the intent is for these routines to be generic why not have them fall back to the P8 barrier instructions for example like x86 clwb(). Any kernel code can call it, and it falls back to a compatible clflush() call on older cpus. I otherwise don't get the point of patch7. ___ Linux-nvdimm mailing list -- linux-nvdimm@lists.01.org To unsubscribe send an email to linux-nvdimm-le...@lists.01.org
Re: [PATCH v6 5/8] powerpc/pmem/of_pmem: Update of_pmem to use the new barrier instruction.
Dan Williams writes: > On Mon, Jun 29, 2020 at 6:58 AM Aneesh Kumar K.V > wrote: >> >> of_pmem on POWER10 can now use phwsync instead of hwsync to ensure >> all previous writes are architecturally visible for the platform >> buffer flush. >> >> Signed-off-by: Aneesh Kumar K.V >> --- >> arch/powerpc/include/asm/cacheflush.h | 7 +++ >> 1 file changed, 7 insertions(+) >> >> diff --git a/arch/powerpc/include/asm/cacheflush.h >> b/arch/powerpc/include/asm/cacheflush.h >> index 54764c6e922d..95782f77d768 100644 >> --- a/arch/powerpc/include/asm/cacheflush.h >> +++ b/arch/powerpc/include/asm/cacheflush.h >> @@ -98,6 +98,13 @@ static inline void invalidate_dcache_range(unsigned long >> start, >> mb(); /* sync */ >> } >> >> +#define arch_pmem_flush_barrier arch_pmem_flush_barrier >> +static inline void arch_pmem_flush_barrier(void) >> +{ >> + if (cpu_has_feature(CPU_FTR_ARCH_207S)) >> + asm volatile(PPC_PHWSYNC ::: "memory"); > > Shouldn't this fallback to a compatible store-fence in an else statement? The idea was to avoid calling this on anything else. We ensure that by making sure that pmem devices are not initialized on systems without that cpu feature. Patch 1 does that. Also, the last patch adds a WARN_ON() to catch the usage of this outside pmem devices and on systems without that cpu feature. -aneesh ___ Linux-nvdimm mailing list -- linux-nvdimm@lists.01.org To unsubscribe send an email to linux-nvdimm-le...@lists.01.org
Re: [PATCH v6 5/8] powerpc/pmem/of_pmem: Update of_pmem to use the new barrier instruction.
On Mon, Jun 29, 2020 at 6:58 AM Aneesh Kumar K.V wrote: > > of_pmem on POWER10 can now use phwsync instead of hwsync to ensure > all previous writes are architecturally visible for the platform > buffer flush. > > Signed-off-by: Aneesh Kumar K.V > --- > arch/powerpc/include/asm/cacheflush.h | 7 +++ > 1 file changed, 7 insertions(+) > > diff --git a/arch/powerpc/include/asm/cacheflush.h > b/arch/powerpc/include/asm/cacheflush.h > index 54764c6e922d..95782f77d768 100644 > --- a/arch/powerpc/include/asm/cacheflush.h > +++ b/arch/powerpc/include/asm/cacheflush.h > @@ -98,6 +98,13 @@ static inline void invalidate_dcache_range(unsigned long > start, > mb(); /* sync */ > } > > +#define arch_pmem_flush_barrier arch_pmem_flush_barrier > +static inline void arch_pmem_flush_barrier(void) > +{ > + if (cpu_has_feature(CPU_FTR_ARCH_207S)) > + asm volatile(PPC_PHWSYNC ::: "memory"); Shouldn't this fallback to a compatible store-fence in an else statement? ___ Linux-nvdimm mailing list -- linux-nvdimm@lists.01.org To unsubscribe send an email to linux-nvdimm-le...@lists.01.org