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From: "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com>
To: Dan Williams <dan.j.williams@intel.com>
Cc: linuxppc-dev <linuxppc-dev@lists.ozlabs.org>,
	"Michael Ellerman" <mpe@ellerman.id.au>,
	linux-nvdimm <linux-nvdimm@lists.01.org>,
	"Jan Kara" <jack@suse.cz>, "Michal Suchánek" <msuchanek@suse.de>
Subject: Re: [PATCH v6 5/8] powerpc/pmem/of_pmem: Update of_pmem to use the new barrier instruction.
Date: Tue, 30 Jun 2020 10:35:12 +0530	[thread overview]
Message-ID: <87ftadgn3r.fsf@linux.ibm.com> (raw)
In-Reply-To: <CAPcyv4hFfU0r0GmCgV-wKXq+H=GDV-OPsGNPWmFijrdWm58X_A@mail.gmail.com>

Dan Williams <dan.j.williams@intel.com> writes:

> On Mon, Jun 29, 2020 at 6:58 AM Aneesh Kumar K.V
> <aneesh.kumar@linux.ibm.com> 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 <aneesh.kumar@linux.ibm.com>
>> ---
>>  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
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  reply	other threads:[~2020-06-30  5:05 UTC|newest]

Thread overview: 33+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-06-29 13:57 [PATCH v6 0/8] Support new pmem flush and sync instructions for POWER Aneesh Kumar K.V
2020-06-29 13:57 ` [PATCH v6 1/8] powerpc/pmem: Restrict papr_scm to P8 and above Aneesh Kumar K.V
2020-06-29 13:57 ` [PATCH v6 2/8] powerpc/pmem: Add new instructions for persistent storage and sync Aneesh Kumar K.V
2020-06-29 13:57 ` [PATCH v6 3/8] powerpc/pmem: Add flush routines using new pmem store and sync instruction Aneesh Kumar K.V
2020-06-29 13:57 ` [PATCH v6 4/8] libnvdimm/nvdimm/flush: Allow architecture to override the flush barrier Aneesh Kumar K.V
2020-06-29 18:53   ` kernel test robot
2020-06-29 20:27     ` Aneesh Kumar K.V
2020-06-29 19:27   ` kernel test robot
2020-06-29 20:29   ` [PATCH updated] " Aneesh Kumar K.V
2020-06-30  1:32     ` Dan Williams
2020-06-30  5:01       ` Aneesh Kumar K.V
2020-06-30  7:06         ` Dan Williams
2020-06-30  7:22           ` Aneesh Kumar K.V
2020-06-30  7:53             ` Aneesh Kumar K.V
2020-06-30 12:48             ` Aneesh Kumar K.V
2020-06-30 19:21               ` Dan Williams
2020-06-29 13:57 ` [PATCH v6 5/8] powerpc/pmem/of_pmem: Update of_pmem to use the new barrier instruction Aneesh Kumar K.V
2020-06-30  1:38   ` Dan Williams
2020-06-30  5:05     ` Aneesh Kumar K.V [this message]
2020-06-30  7:16       ` Dan Williams
2020-06-29 13:57 ` [PATCH v6 6/8] powerpc/pmem: Avoid the barrier in flush routines Aneesh Kumar K.V
2020-06-29 16:09   ` Michal Suchánek
2020-06-29 20:40     ` Aneesh Kumar K.V
2020-06-30  1:50       ` Dan Williams
2020-06-30  8:54         ` Michal Suchánek
2020-06-30  9:20           ` Aneesh Kumar K.V
2020-06-30 19:45             ` Dan Williams
2020-07-01  3:09               ` Aneesh Kumar K.V
2020-07-01  5:08                 ` Dan Williams
2020-06-29 13:57 ` [PATCH v6 7/8] powerpc/pmem: Add WARN_ONCE to catch the wrong usage of pmem flush functions Aneesh Kumar K.V
2020-06-30  1:52   ` Dan Williams
2020-06-30  5:05     ` Aneesh Kumar K.V
2020-06-29 13:57 ` [PATCH v6 8/8] powerpc/pmem: Initialize pmem device on newer hardware Aneesh Kumar K.V

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