* [PATCH 0/2] Add DAX ABI for memmap_on_memory
@ 2023-12-07 4:29 Vishal Verma
2023-12-07 4:29 ` [PATCH 2/2] dax: add a sysfs knob to control memmap_on_memory behavior Vishal Verma
0 siblings, 1 reply; 2+ messages in thread
From: Vishal Verma @ 2023-12-07 4:29 UTC (permalink / raw
To: Dan Williams, Vishal Verma
Cc: David Hildenbrand, Dave Jiang, Dave Hansen, Huang Ying,
Jonathan Cameron, nvdimm
The DAX drivers were missing sysfs ABI documentation entirely. Add this
missing documentation for the sysfs ABI for DAX regions and Dax devices
in patch 1. Add a new ABI for toggling memmap_on_memory semantics in
patch 2.
The missing ABI was spotted in [1], this series is a split of the new
ABI additions behind the initial documentation creation.
[1]: https://lore.kernel.org/linux-cxl/651f27b728fef_ae7e7294b3@dwillia2-xfh.jf.intel.com.notmuch/
Signed-off-by: Vishal Verma <vishal.l.verma@intel.com>
---
Vishal Verma (2):
Documentatiion/ABI: Add ABI documentation for sys-bus-dax
dax: add a sysfs knob to control memmap_on_memory behavior
drivers/dax/bus.c | 40 ++++++++
Documentation/ABI/testing/sysfs-bus-dax | 164 ++++++++++++++++++++++++++++++++
2 files changed, 204 insertions(+)
---
base-commit: c4e1ccfad42352918810802095a8ace8d1c744c9
change-id: 20231025-vv-dax_abi-17a219c46076
Best regards,
--
Vishal Verma <vishal.l.verma@intel.com>
^ permalink raw reply [flat|nested] 2+ messages in thread
* [PATCH 2/2] dax: add a sysfs knob to control memmap_on_memory behavior
2023-12-07 4:29 [PATCH 0/2] Add DAX ABI for memmap_on_memory Vishal Verma
@ 2023-12-07 4:29 ` Vishal Verma
0 siblings, 0 replies; 2+ messages in thread
From: Vishal Verma @ 2023-12-07 4:29 UTC (permalink / raw
To: Dan Williams, Vishal Verma
Cc: David Hildenbrand, Dave Jiang, Dave Hansen, Huang Ying,
Jonathan Cameron, nvdimm
Add a sysfs knob for dax devices to control the memmap_on_memory setting
if the dax device were to be hotplugged as system memory.
The default memmap_on_memory setting for dax devices originating via
pmem or hmem is set to 'false' - i.e. no memmap_on_memory semantics, to
preserve legacy behavior. For dax devices via CXL, the default is on.
The sysfs control allows the administrator to override the above
defaults if needed.
Cc: David Hildenbrand <david@redhat.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Dave Jiang <dave.jiang@intel.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Huang Ying <ying.huang@intel.com>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Vishal Verma <vishal.l.verma@intel.com>
---
drivers/dax/bus.c | 40 +++++++++++++++++++++++++++++++++
Documentation/ABI/testing/sysfs-bus-dax | 13 +++++++++++
2 files changed, 53 insertions(+)
diff --git a/drivers/dax/bus.c b/drivers/dax/bus.c
index 1ff1ab5fa105..11abb57cc031 100644
--- a/drivers/dax/bus.c
+++ b/drivers/dax/bus.c
@@ -1270,6 +1270,45 @@ static ssize_t numa_node_show(struct device *dev,
}
static DEVICE_ATTR_RO(numa_node);
+static ssize_t memmap_on_memory_show(struct device *dev,
+ struct device_attribute *attr, char *buf)
+{
+ struct dev_dax *dev_dax = to_dev_dax(dev);
+
+ return sprintf(buf, "%d\n", dev_dax->memmap_on_memory);
+}
+
+static ssize_t memmap_on_memory_store(struct device *dev,
+ struct device_attribute *attr,
+ const char *buf, size_t len)
+{
+ struct dev_dax *dev_dax = to_dev_dax(dev);
+ struct dax_region *dax_region = dev_dax->region;
+ ssize_t rc;
+ bool val;
+
+ rc = kstrtobool(buf, &val);
+ if (rc)
+ return rc;
+
+ if (dev_dax->memmap_on_memory == val)
+ return len;
+
+ device_lock(dax_region->dev);
+ if (!dax_region->dev->driver) {
+ device_unlock(dax_region->dev);
+ return -ENXIO;
+ }
+
+ device_lock(dev);
+ dev_dax->memmap_on_memory = val;
+ device_unlock(dev);
+
+ device_unlock(dax_region->dev);
+ return rc == 0 ? len : rc;
+}
+static DEVICE_ATTR_RW(memmap_on_memory);
+
static umode_t dev_dax_visible(struct kobject *kobj, struct attribute *a, int n)
{
struct device *dev = container_of(kobj, struct device, kobj);
@@ -1296,6 +1335,7 @@ static struct attribute *dev_dax_attributes[] = {
&dev_attr_align.attr,
&dev_attr_resource.attr,
&dev_attr_numa_node.attr,
+ &dev_attr_memmap_on_memory.attr,
NULL,
};
diff --git a/Documentation/ABI/testing/sysfs-bus-dax b/Documentation/ABI/testing/sysfs-bus-dax
index a61a7b186017..bb063a004e41 100644
--- a/Documentation/ABI/testing/sysfs-bus-dax
+++ b/Documentation/ABI/testing/sysfs-bus-dax
@@ -149,3 +149,16 @@ KernelVersion: v5.1
Contact: nvdimm@lists.linux.dev
Description:
(RO) The id attribute indicates the region id of a dax region.
+
+What: /sys/bus/dax/devices/daxX.Y/memmap_on_memory
+Date: October, 2023
+KernelVersion: v6.8
+Contact: nvdimm@lists.linux.dev
+Description:
+ (RW) Control the memmap_on_memory setting if the dax device
+ were to be hotplugged as system memory. This determines whether
+ the 'altmap' for the hotplugged memory will be placed on the
+ device being hotplugged (memmap_on+memory=1) or if it will be
+ placed on regular memory (memmap_on_memory=0). This attribute
+ must be set before the device is handed over to the 'kmem'
+ driver (i.e. hotplugged into system-ram).
--
2.41.0
^ permalink raw reply related [flat|nested] 2+ messages in thread
end of thread, other threads:[~2023-12-07 4:29 UTC | newest]
Thread overview: 2+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2023-12-07 4:29 [PATCH 0/2] Add DAX ABI for memmap_on_memory Vishal Verma
2023-12-07 4:29 ` [PATCH 2/2] dax: add a sysfs knob to control memmap_on_memory behavior Vishal Verma
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).