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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
Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com>
Subject: [PATCH v4 1/8] powerpc/pmem: Restrict papr_scm to P8 and above.
Date: Fri, 29 May 2020 10:58:13 +0530	[thread overview]
Message-ID: <20200529052820.151651-2-aneesh.kumar@linux.ibm.com> (raw)
In-Reply-To: <20200529052820.151651-1-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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WARNING: multiple messages have this Message-ID (diff)
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
Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com>,
	dan.j.williams@intel.com, oohall@gmail.com
Subject: [PATCH v4 1/8] powerpc/pmem: Restrict papr_scm to P8 and above.
Date: Fri, 29 May 2020 10:58:13 +0530	[thread overview]
Message-ID: <20200529052820.151651-2-aneesh.kumar@linux.ibm.com> (raw)
In-Reply-To: <20200529052820.151651-1-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


  reply	other threads:[~2020-05-29  5:28 UTC|newest]

Thread overview: 21+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-05-29  5:28 [PATCH v4 0/8] Support new pmem flush and sync instructions for POWER Aneesh Kumar K.V
2020-05-29  5:28 ` Aneesh Kumar K.V
2020-05-29  5:28 ` Aneesh Kumar K.V [this message]
2020-05-29  5:28   ` [PATCH v4 1/8] powerpc/pmem: Restrict papr_scm to P8 and above Aneesh Kumar K.V
2020-05-29  5:28 ` [PATCH v4 2/8] powerpc/pmem: Add new instructions for persistent storage and sync Aneesh Kumar K.V
2020-05-29  5:28   ` Aneesh Kumar K.V
2020-05-29  5:28 ` [PATCH v4 3/8] powerpc/pmem: Add flush routines using new pmem store and sync instruction Aneesh Kumar K.V
2020-05-29  5:28   ` Aneesh Kumar K.V
2020-05-29  5:28 ` [PATCH v4 4/8] libnvdimm/nvdimm/flush: Allow architecture to override the flush barrier Aneesh Kumar K.V
2020-05-29  5:28   ` Aneesh Kumar K.V
2020-05-29  5:28 ` [PATCH v4 5/8] powerpc/pmem/of_pmem: Update of_pmem to use the new barrier instruction Aneesh Kumar K.V
2020-05-29  5:28   ` Aneesh Kumar K.V
2020-05-31 14:46   ` kbuild test robot
2020-05-31 14:46     ` kbuild test robot
2020-05-31 14:46     ` kbuild test robot
2020-05-29  5:28 ` [PATCH v4 6/8] powerpc/pmem: Avoid the barrier in flush routines Aneesh Kumar K.V
2020-05-29  5:28   ` Aneesh Kumar K.V
2020-05-29  5:28 ` [PATCH v4 7/8] powerpc/book3s/pmem: Add WARN_ONCE to catch the wrong usage of pmem flush functions Aneesh Kumar K.V
2020-05-29  5:28   ` Aneesh Kumar K.V
2020-05-29  5:28 ` [PATCH v4 8/8] powerpc/pmem: Initialize pmem device on newer hardware Aneesh Kumar K.V
2020-05-29  5:28   ` Aneesh Kumar K.V

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