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[PATCH v2 0/3] libnvdimm, pfn: support section misaligned pmem

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  [PATCH v2 0/3] libnvdimm, pfn: support section misaligned pmem Dan Williams <dan.j.williams@intel.com> - 2016-03-03 23:00 +0100
    [PATCH v2 1/3] libnvdimm,  pmem: fix 'pfn' support for section-misaligned namespaces Dan Williams <dan.j.williams@intel.com> - 2016-03-03 23:00 +0100
    [PATCH v2 3/3] libnvdimm,  pfn: 'resource'-address and 'size' attributes for pfn devices Dan Williams <dan.j.williams@intel.com> - 2016-03-03 23:00 +0100

#1349613 — [PATCH v2 0/3] libnvdimm, pfn: support section misaligned pmem

Permit platforms with section-misaligned persistent memory to establish
memory-mode (pfn) namespaces.  This sacrifices 64-128MB of pmem to gain
third-party DMA/RDMA support.

Changes since v1 [1]:

1/ Dropped "mm: fix mixed zone detection in devm_memremap_pages" since
   it was pulled into Andrew's tree.

2/ Moved CONFIG_SPARSEMEM #ifdef guards into drivers/nvdimm/pfn.h

3/ Added "libnvdimm, pmem: adjust for section collisions with 'System
   RAM'", i.e. support for reserving head and tail capacity out of a
   namespace to permit a section aligned range to be used for a
   'pfn'-device instance.

4/ Added 'resource' and 'size' attributes to an active pfn instance.

[1]: https://lists.01.org/pipermail/linux-nvdimm/2016-February/004727.html

This series is built on top of tip.git/core/resources.

---

Dan Williams (3):
      libnvdimm, pmem: fix 'pfn' support for section-misaligned namespaces
      libnvdimm, pmem: adjust for section collisions with 'System RAM'
      libnvdimm, pfn: 'resource'-address and 'size' attributes for pfn devices


 drivers/nvdimm/namespace_devs.c |    7 ++
 drivers/nvdimm/pfn.h            |   23 ++++++
 drivers/nvdimm/pfn_devs.c       |   61 ++++++++++++++++
 drivers/nvdimm/pmem.c           |  145 ++++++++++++++++++++++++++++++---------
 4 files changed, 200 insertions(+), 36 deletions(-)

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#1349614 — [PATCH v2 1/3] libnvdimm, pmem: fix 'pfn' support for section-misaligned namespaces

The altmap for a section-misaligned namespace needs to arrange for the
base_pfn to be section-aligned.  As a result the 'reserve' region (pfns
from base that do not have a struct page) must be increased.  Otherwise
we trip the altmap validation check in __add_pages:

	if (altmap->base_pfn != phys_start_pfn
			|| vmem_altmap_offset(altmap) > nr_pages) {
		pr_warn_once("memory add fail, invalid altmap\n");
		return -EINVAL;
	}

Signed-off-by: Dan Williams <dan.j.williams@intel.com>
---
 drivers/nvdimm/pfn.h  |   13 +++++++++++++
 drivers/nvdimm/pmem.c |   24 ++++++++++++++++++++++--
 2 files changed, 35 insertions(+), 2 deletions(-)

diff --git a/drivers/nvdimm/pfn.h b/drivers/nvdimm/pfn.h
index cc243754acef..6ee707e5b279 100644
--- a/drivers/nvdimm/pfn.h
+++ b/drivers/nvdimm/pfn.h
@@ -15,6 +15,7 @@
 #define __NVDIMM_PFN_H
 
 #include <linux/types.h>
+#include <linux/mmzone.h>
 
 #define PFN_SIG_LEN 16
 #define PFN_SIG "NVDIMM_PFN_INFO\0"
@@ -32,4 +33,16 @@ struct nd_pfn_sb {
 	u8 padding[4012];
 	__le64 checksum;
 };
+
+#ifdef CONFIG_SPARSEMEM
+#define PFN_SECTION_ALIGN_DOWN(x) SECTION_ALIGN_DOWN(x)
+#define PFN_SECTION_ALIGN_UP(x) SECTION_ALIGN_UP(x)
+#else
+/*
+ * In this case ZONE_DEVICE=n and we will disable 'pfn' device support,
+ * but we still want pmem to compile.
+ */
+#define PFN_SECTION_ALIGN_DOWN(x) (x)
+#define PFN_SECTION_ALIGN_UP(x) (x)
+#endif
 #endif /* __NVDIMM_PFN_H */
diff --git a/drivers/nvdimm/pmem.c b/drivers/nvdimm/pmem.c
index 7edf31671dab..68a20b2e3d03 100644
--- a/drivers/nvdimm/pmem.c
+++ b/drivers/nvdimm/pmem.c
@@ -356,6 +356,26 @@ static int nvdimm_namespace_detach_pfn(struct nd_namespace_common *ndns)
 	return 0;
 }
 
+/*
+ * We hotplug memory at section granularity, pad the reserved area from
+ * the previous section base to the namespace base address.
+ */
+static unsigned long init_altmap_base(resource_size_t base)
+{
+	unsigned long base_pfn = __phys_to_pfn(base);
+
+	return PFN_SECTION_ALIGN_DOWN(base_pfn);
+}
+
+static unsigned long init_altmap_reserve(resource_size_t base)
+{
+	unsigned long reserve = __phys_to_pfn(SZ_8K);
+	unsigned long base_pfn = __phys_to_pfn(base);
+
+	reserve += base_pfn - PFN_SECTION_ALIGN_DOWN(base_pfn);
+	return reserve;
+}
+
 static int nvdimm_namespace_attach_pfn(struct nd_namespace_common *ndns)
 {
 	struct nd_namespace_io *nsio = to_nd_namespace_io(&ndns->dev);
@@ -369,8 +389,8 @@ static int nvdimm_namespace_attach_pfn(struct nd_namespace_common *ndns)
 	phys_addr_t offset;
 	int rc;
 	struct vmem_altmap __altmap = {
-		.base_pfn = __phys_to_pfn(nsio->res.start),
-		.reserve = __phys_to_pfn(SZ_8K),
+		.base_pfn = init_altmap_base(nsio->res.start),
+		.reserve = init_altmap_reserve(nsio->res.start),
 	};
 
 	if (!nd_pfn->uuid || !nd_pfn->ndns)

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#1349615 — [PATCH v2 3/3] libnvdimm, pfn: 'resource'-address and 'size' attributes for pfn devices

Currenty with a raw mode pmem namespace the physical memory address range for
the device can be obtained via /sys/block/pmemX/device/{resource|size}.  Add
similar attributes for pfn instances that takes the struct page memmap and
section padding into account.

Reported-by: Haozhong Zhang <haozhong.zhang@intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
---
 drivers/nvdimm/pfn_devs.c |   56 +++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 56 insertions(+)

diff --git a/drivers/nvdimm/pfn_devs.c b/drivers/nvdimm/pfn_devs.c
index 14642617a153..a43942ffc173 100644
--- a/drivers/nvdimm/pfn_devs.c
+++ b/drivers/nvdimm/pfn_devs.c
@@ -205,11 +205,67 @@ static ssize_t namespace_store(struct device *dev,
 }
 static DEVICE_ATTR_RW(namespace);
 
+static ssize_t resource_show(struct device *dev,
+		struct device_attribute *attr, char *buf)
+{
+	struct nd_pfn *nd_pfn = to_nd_pfn(dev);
+	ssize_t rc;
+
+	device_lock(dev);
+	if (dev->driver) {
+		struct nd_pfn_sb *pfn_sb = nd_pfn->pfn_sb;
+		u64 offset = __le64_to_cpu(pfn_sb->dataoff);
+		struct nd_namespace_common *ndns = nd_pfn->ndns;
+		u32 start_pad = __le32_to_cpu(pfn_sb->start_pad);
+		struct nd_namespace_io *nsio = to_nd_namespace_io(&ndns->dev);
+
+		rc = sprintf(buf, "%#llx\n", (unsigned long long) nsio->res.start
+				+ start_pad + offset);
+	} else {
+		/* no address to convey if the pfn instance is disabled */
+		rc = -ENXIO;
+	}
+	device_unlock(dev);
+
+	return rc;
+}
+static DEVICE_ATTR_RO(resource);
+
+static ssize_t size_show(struct device *dev,
+		struct device_attribute *attr, char *buf)
+{
+	struct nd_pfn *nd_pfn = to_nd_pfn(dev);
+	ssize_t rc;
+
+	device_lock(dev);
+	if (dev->driver) {
+		struct nd_pfn_sb *pfn_sb = nd_pfn->pfn_sb;
+		u64 offset = __le64_to_cpu(pfn_sb->dataoff);
+		struct nd_namespace_common *ndns = nd_pfn->ndns;
+		u32 start_pad = __le32_to_cpu(pfn_sb->start_pad);
+		u32 end_trunc = __le32_to_cpu(pfn_sb->end_trunc);
+		struct nd_namespace_io *nsio = to_nd_namespace_io(&ndns->dev);
+
+		rc = sprintf(buf, "%llu\n", (unsigned long long)
+				resource_size(&nsio->res) - start_pad
+				- end_trunc - offset);
+	} else {
+		/* no size to convey if the pfn instance is disabled */
+		rc = -ENXIO;
+	}
+	device_unlock(dev);
+
+	return rc;
+}
+static DEVICE_ATTR_RO(size);
+
 static struct attribute *nd_pfn_attributes[] = {
 	&dev_attr_mode.attr,
 	&dev_attr_namespace.attr,
 	&dev_attr_uuid.attr,
 	&dev_attr_align.attr,
+	&dev_attr_resource.attr,
+	&dev_attr_size.attr,
 	NULL,
 };
 

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