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From: "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com>
To: linuxppc-dev@lists.ozlabs.org, mpe@ellerman.id.au,
	linux-nvdimm@lists.01.org, dan.j.williams@intel.com
Cc: Jan Kara <jack@suse.cz>,
	msuchanek@suse.de,
	"Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com>
Subject: [PATCH v6 1/8] powerpc/pmem: Restrict papr_scm to P8 and above.
Date: Mon, 29 Jun 2020 19:27:15 +0530	[thread overview]
Message-ID: <20200629135722.73558-2-aneesh.kumar@linux.ibm.com> (raw)
In-Reply-To: <20200629135722.73558-1-aneesh.kumar@linux.ibm.com>

The PAPR based virtualized persistent memory devices are only supported on
POWER9 and above. In the followup patch, the kernel will switch the persistent
memory cache flush functions to use a new `dcbf` variant instruction. The new
instructions even though added in ISA 3.1 works even on P8 and P9 because these
are implemented as a variant of existing `dcbf` and `hwsync` and on P8 and
P9 behaves as such.

Considering these devices are only supported on P8 and above,  update the driver
to prevent a P7-compat guest from using persistent memory devices.

We don't update of_pmem driver with the same condition, because, on bare-metal,
the firmware enables pmem support only on P9 and above. There the kernel depends
on OPAL firmware to restrict exposing persistent memory related device tree
entries on older hardware. of_pmem.ko is written without any arch dependency and
we don't want to add ppc64 specific cpu feature check in of_pmem driver.

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
---
 arch/powerpc/platforms/pseries/pmem.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/arch/powerpc/platforms/pseries/pmem.c b/arch/powerpc/platforms/pseries/pmem.c
index f860a897a9e0..2347e1038f58 100644
--- a/arch/powerpc/platforms/pseries/pmem.c
+++ b/arch/powerpc/platforms/pseries/pmem.c
@@ -147,6 +147,12 @@ const struct of_device_id drc_pmem_match[] = {
 
 static int pseries_pmem_init(void)
 {
+	/*
+	 * Only supported on POWER8 and above.
+	 */
+	if (!cpu_has_feature(CPU_FTR_ARCH_207S))
+		return 0;
+
 	pmem_node = of_find_node_by_type(NULL, "ibm,persistent-memory");
 	if (!pmem_node)
 		return 0;
-- 
2.26.2
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  reply	other threads:[~2020-06-29 13:57 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 ` Aneesh Kumar K.V [this message]
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
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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