[RFC,V2,16/17,dax|pmem] : Enable stray write protection
diff mbox series

Message ID 20200717072056.73134-17-ira.weiny@intel.com
State New
Headers show
Series
  • PKS: Add Protection Keys Supervisor (PKS) support
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Commit Message

Ira Weiny July 17, 2020, 7:20 a.m. UTC
From: Ira Weiny <ira.weiny@intel.com>

Protecting against stray writes is particularly important for PMEM
because, unlike writes to anonymous memory, writes to PMEM persists
across a reboot.  Thus data corruption could result in permanent loss of
data.  Therefore, there is no option presented to the user.

Enable stray write protection by setting the flag in pgmap which
requests it.  Note if Zone Device Access Protection not be supported
this flag will have no affect.

Signed-off-by: Ira Weiny <ira.weiny@intel.com>
---
 drivers/dax/device.c  | 2 ++
 drivers/nvdimm/pmem.c | 2 ++
 2 files changed, 4 insertions(+)

Comments

Peter Zijlstra July 17, 2020, 9:25 a.m. UTC | #1
On Fri, Jul 17, 2020 at 12:20:55AM -0700, ira.weiny@intel.com wrote:
> From: Ira Weiny <ira.weiny@intel.com>
> 
> Protecting against stray writes is particularly important for PMEM
> because, unlike writes to anonymous memory, writes to PMEM persists
> across a reboot.  Thus data corruption could result in permanent loss of
> data.  Therefore, there is no option presented to the user.
> 
> Enable stray write protection by setting the flag in pgmap which
> requests it.  Note if Zone Device Access Protection not be supported
> this flag will have no affect.

The actual implementation is stray-access-protection, as noted ealier.
This inconsisteny is throughout.

Patch
diff mbox series

diff --git a/drivers/dax/device.c b/drivers/dax/device.c
index 4c0af2eb7e19..884f66d73d32 100644
--- a/drivers/dax/device.c
+++ b/drivers/dax/device.c
@@ -430,6 +430,8 @@  int dev_dax_probe(struct device *dev)
 	}
 
 	dev_dax->pgmap.type = MEMORY_DEVICE_DEVDAX;
+	dev_dax->pgmap.flags |= PGMAP_PROT_ENABLED;
+
 	addr = devm_memremap_pages(dev, &dev_dax->pgmap);
 	if (IS_ERR(addr))
 		return PTR_ERR(addr);
diff --git a/drivers/nvdimm/pmem.c b/drivers/nvdimm/pmem.c
index 46c11a09b813..9416a660eede 100644
--- a/drivers/nvdimm/pmem.c
+++ b/drivers/nvdimm/pmem.c
@@ -427,6 +427,8 @@  static int pmem_attach_disk(struct device *dev,
 		return -EBUSY;
 	}
 
+	pmem->pgmap.flags |= PGMAP_PROT_ENABLED;
+
 	q = blk_alloc_queue(pmem_make_request, dev_to_node(dev));
 	if (!q)
 		return -ENOMEM;