libnvdimm, pmem: adjust for section collisions with 'System RAM'

On a platform where 'Persistent Memory' and 'System RAM' are mixed
within a given sparsemem section, trim the namespace and notify about the
sub-optimal alignment.

Cc: Toshi Kani <toshi.kani@hpe.com>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

4 files changed, 111 insertions, 36 deletions

diff --git a/drivers/nvdimm/namespace_devs.c b/drivers/nvdimm/namespace_devs.c
index 9edf7eb7d17c..f5cb88601359 100644
--- a/drivers/nvdimm/namespace_devs.c
+++ b/drivers/nvdimm/namespace_devs.c
@@ -133,6 +133,7 @@ bool nd_is_uuid_unique(struct device *dev, u8 *uuid)
 bool pmem_should_map_pages(struct device *dev)
 {
         struct nd_region *nd_region = to_nd_region(dev->parent);
+        struct nd_namespace_io *nsio;
 
         if (!IS_ENABLED(CONFIG_ZONE_DEVICE))
                 return false;
@@ -143,6 +144,12 @@ bool pmem_should_map_pages(struct device *dev)
         if (is_nd_pfn(dev) || is_nd_btt(dev))
                 return false;
 
+        nsio = to_nd_namespace_io(dev);
+        if (region_intersects(nsio->res.start, resource_size(&nsio->res),
+                                IORESOURCE_SYSTEM_RAM,
+                                IORES_DESC_NONE) == REGION_MIXED)
+                return false;
+
 #ifdef ARCH_MEMREMAP_PMEM
         return ARCH_MEMREMAP_PMEM == MEMREMAP_WB;
 #else
diff --git a/drivers/nvdimm/pfn.h b/drivers/nvdimm/pfn.h
index 6ee707e5b279..8e343a3ca873 100644
--- a/drivers/nvdimm/pfn.h
+++ b/drivers/nvdimm/pfn.h
@@ -27,10 +27,13 @@ struct nd_pfn_sb {
         __le32 flags;
         __le16 version_major;
         __le16 version_minor;
-        __le64 dataoff;
+        __le64 dataoff; /* relative to namespace_base + start_pad */
         __le64 npfns;
         __le32 mode;
-        u8 padding[4012];
+        /* minor-version-1 additions for section alignment */
+        __le32 start_pad;
+        __le32 end_trunc;
+        u8 padding[4004];
         __le64 checksum;
 };
 
@@ -45,4 +48,7 @@ struct nd_pfn_sb {
 #define PFN_SECTION_ALIGN_DOWN(x) (x)
 #define PFN_SECTION_ALIGN_UP(x) (x)
 #endif
+
+#define PHYS_SECTION_ALIGN_DOWN(x) PFN_PHYS(PFN_SECTION_ALIGN_DOWN(PHYS_PFN(x)))
+#define PHYS_SECTION_ALIGN_UP(x) PFN_PHYS(PFN_SECTION_ALIGN_UP(PHYS_PFN(x)))
 #endif /* __NVDIMM_PFN_H */
diff --git a/drivers/nvdimm/pfn_devs.c b/drivers/nvdimm/pfn_devs.c
index ae81a2f1da50..75a31a7359fb 100644
--- a/drivers/nvdimm/pfn_devs.c
+++ b/drivers/nvdimm/pfn_devs.c
@@ -299,6 +299,11 @@ int nd_pfn_validate(struct nd_pfn *nd_pfn)
         if (memcmp(pfn_sb->parent_uuid, parent_uuid, 16) != 0)
                 return -ENODEV;
 
+        if (__le16_to_cpu(pfn_sb->version_minor) < 1) {
+                pfn_sb->start_pad = 0;
+                pfn_sb->end_trunc = 0;
+        }
+
         switch (le32_to_cpu(pfn_sb->mode)) {
         case PFN_MODE_RAM:
         case PFN_MODE_PMEM:
diff --git a/drivers/nvdimm/pmem.c b/drivers/nvdimm/pmem.c
index 59d568ab7556..0cb450e1b400 100644
--- a/drivers/nvdimm/pmem.c
+++ b/drivers/nvdimm/pmem.c
@@ -43,7 +43,10 @@ struct pmem_device {
         phys_addr_t             data_offset;
         u64                     pfn_flags;
         void __pmem             *virt_addr;
+        /* immutable base size of the namespace */
         size_t                  size;
+        /* trim size when namespace capacity has been section aligned */
+        u32                     pfn_pad;
         struct badblocks        bb;
 };
 
@@ -145,7 +148,7 @@ static long pmem_direct_access(struct block_device *bdev, sector_t sector,
         *kaddr = pmem->virt_addr + offset;
         *pfn = phys_to_pfn_t(pmem->phys_addr + offset, pmem->pfn_flags);
 
-        return pmem->size - offset;
+        return pmem->size - pmem->pfn_pad - offset;
 }
 
 static const struct block_device_operations pmem_fops = {
@@ -236,7 +239,8 @@ static int pmem_attach_disk(struct device *dev,
         disk->flags             = GENHD_FL_EXT_DEVT;
         nvdimm_namespace_disk_name(ndns, disk->disk_name);
         disk->driverfs_dev = dev;
-        set_capacity(disk, (pmem->size - pmem->data_offset) / 512);
+        set_capacity(disk, (pmem->size - pmem->pfn_pad - pmem->data_offset)
+                        / 512);
         pmem->pmem_disk = disk;
         devm_exit_badblocks(dev, &pmem->bb);
         if (devm_init_badblocks(dev, &pmem->bb))
@@ -279,6 +283,9 @@ static int nd_pfn_init(struct nd_pfn *nd_pfn)
         struct nd_pfn_sb *pfn_sb = kzalloc(sizeof(*pfn_sb), GFP_KERNEL);
         struct pmem_device *pmem = dev_get_drvdata(&nd_pfn->dev);
         struct nd_namespace_common *ndns = nd_pfn->ndns;
+        u32 start_pad = 0, end_trunc = 0;
+        resource_size_t start, size;
+        struct nd_namespace_io *nsio;
         struct nd_region *nd_region;
         unsigned long npfns;
         phys_addr_t offset;
@@ -304,21 +311,56 @@ static int nd_pfn_init(struct nd_pfn *nd_pfn)
         }
 
         memset(pfn_sb, 0, sizeof(*pfn_sb));
-        npfns = (pmem->size - SZ_8K) / SZ_4K;
+
+        /*
+         * Check if pmem collides with 'System RAM' when section aligned and
+         * trim it accordingly
+         */
+        nsio = to_nd_namespace_io(&ndns->dev);
+        start = PHYS_SECTION_ALIGN_DOWN(nsio->res.start);
+        size = resource_size(&nsio->res);
+        if (region_intersects(start, size, IORESOURCE_SYSTEM_RAM,
+                                IORES_DESC_NONE) == REGION_MIXED) {
+
+                start = nsio->res.start;
+                start_pad = PHYS_SECTION_ALIGN_UP(start) - start;
+        }
+
+        start = nsio->res.start;
+        size = PHYS_SECTION_ALIGN_UP(start + size) - start;
+        if (region_intersects(start, size, IORESOURCE_SYSTEM_RAM,
+                                IORES_DESC_NONE) == REGION_MIXED) {
+                size = resource_size(&nsio->res);
+                end_trunc = start + size - PHYS_SECTION_ALIGN_DOWN(start + size);
+        }
+
+        if (start_pad + end_trunc)
+                dev_info(&nd_pfn->dev, "%s section collision, truncate %d bytes\n",
+                                dev_name(&ndns->dev), start_pad + end_trunc);
+
         /*
          * Note, we use 64 here for the standard size of struct page,
          * debugging options may cause it to be larger in which case the
          * implementation will limit the pfns advertised through
          * ->direct_access() to those that are included in the memmap.
          */
+        start += start_pad;
+        npfns = (pmem->size - start_pad - end_trunc - SZ_8K) / SZ_4K;
         if (nd_pfn->mode == PFN_MODE_PMEM)
-                offset = ALIGN(SZ_8K + 64 * npfns, nd_pfn->align);
+                offset = ALIGN(start + SZ_8K + 64 * npfns, nd_pfn->align)
+                        - start;
         else if (nd_pfn->mode == PFN_MODE_RAM)
-                offset = ALIGN(SZ_8K, nd_pfn->align);
+                offset = ALIGN(start + SZ_8K, nd_pfn->align) - start;
         else
                 goto err;
 
-        npfns = (pmem->size - offset) / SZ_4K;
+        if (offset + start_pad + end_trunc >= pmem->size) {
+                dev_err(&nd_pfn->dev, "%s unable to satisfy requested alignment\n",
+                                dev_name(&ndns->dev));
+                goto err;
+        }
+
+        npfns = (pmem->size - offset - start_pad - end_trunc) / SZ_4K;
         pfn_sb->mode = cpu_to_le32(nd_pfn->mode);
         pfn_sb->dataoff = cpu_to_le64(offset);
         pfn_sb->npfns = cpu_to_le64(npfns);
@@ -326,6 +368,9 @@ static int nd_pfn_init(struct nd_pfn *nd_pfn)
         memcpy(pfn_sb->uuid, nd_pfn->uuid, 16);
         memcpy(pfn_sb->parent_uuid, nd_dev_to_uuid(&ndns->dev), 16);
         pfn_sb->version_major = cpu_to_le16(1);
+        pfn_sb->version_minor = cpu_to_le16(1);
+        pfn_sb->start_pad = cpu_to_le32(start_pad);
+        pfn_sb->end_trunc = cpu_to_le32(end_trunc);
         checksum = nd_sb_checksum((struct nd_gen_sb *) pfn_sb);
         pfn_sb->checksum = cpu_to_le64(checksum);
 
@@ -376,41 +421,36 @@ static unsigned long init_altmap_reserve(resource_size_t base)
         return reserve;
 }
 
-static int nvdimm_namespace_attach_pfn(struct nd_namespace_common *ndns)
+static int __nvdimm_namespace_attach_pfn(struct nd_pfn *nd_pfn)
 {
-        struct nd_namespace_io *nsio = to_nd_namespace_io(&ndns->dev);
-        struct nd_pfn *nd_pfn = to_nd_pfn(ndns->claim);
-        struct device *dev = &nd_pfn->dev;
-        struct nd_region *nd_region;
-        struct vmem_altmap *altmap;
-        struct nd_pfn_sb *pfn_sb;
-        struct pmem_device *pmem;
-        struct request_queue *q;
-        phys_addr_t offset;
         int rc;
+        struct resource res;
+        struct request_queue *q;
+        struct pmem_device *pmem;
+        struct vmem_altmap *altmap;
+        struct device *dev = &nd_pfn->dev;
+        struct nd_pfn_sb *pfn_sb = nd_pfn->pfn_sb;
+        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);
+        resource_size_t base = nsio->res.start + start_pad;
         struct vmem_altmap __altmap = {
-                .base_pfn = init_altmap_base(nsio->res.start),
-                .reserve = init_altmap_reserve(nsio->res.start),
+                .base_pfn = init_altmap_base(base),
+                .reserve = init_altmap_reserve(base),
         };
 
-        if (!nd_pfn->uuid || !nd_pfn->ndns)
-                return -ENODEV;
-
-        nd_region = to_nd_region(dev->parent);
-        rc = nd_pfn_init(nd_pfn);
-        if (rc)
-                return rc;
-
-        pfn_sb = nd_pfn->pfn_sb;
-        offset = le64_to_cpu(pfn_sb->dataoff);
+        pmem = dev_get_drvdata(dev);
+        pmem->data_offset = le64_to_cpu(pfn_sb->dataoff);
+        pmem->pfn_pad = start_pad + end_trunc;
         nd_pfn->mode = le32_to_cpu(nd_pfn->pfn_sb->mode);
         if (nd_pfn->mode == PFN_MODE_RAM) {
-                if (offset < SZ_8K)
+                if (pmem->data_offset < SZ_8K)
                         return -EINVAL;
                 nd_pfn->npfns = le64_to_cpu(pfn_sb->npfns);
                 altmap = NULL;
         } else if (nd_pfn->mode == PFN_MODE_PMEM) {
-                nd_pfn->npfns = (resource_size(&nsio->res) - offset)
+                nd_pfn->npfns = (pmem->size - pmem->pfn_pad - pmem->data_offset)
                         / PAGE_SIZE;
                 if (le64_to_cpu(nd_pfn->pfn_sb->npfns) > nd_pfn->npfns)
                         dev_info(&nd_pfn->dev,
@@ -418,7 +458,7 @@ static int nvdimm_namespace_attach_pfn(struct nd_namespace_common *ndns)
                                         le64_to_cpu(nd_pfn->pfn_sb->npfns),
                                         nd_pfn->npfns);
                 altmap = & __altmap;
-                altmap->free = __phys_to_pfn(offset - SZ_8K);
+                altmap->free = __phys_to_pfn(pmem->data_offset - SZ_8K);
                 altmap->alloc = 0;
         } else {
                 rc = -ENXIO;
@@ -426,10 +466,12 @@ static int nvdimm_namespace_attach_pfn(struct nd_namespace_common *ndns)
         }
 
         /* establish pfn range for lookup, and switch to direct map */
-        pmem = dev_get_drvdata(dev);
         q = pmem->pmem_queue;
+        memcpy(&res, &nsio->res, sizeof(res));
+        res.start += start_pad;
+        res.end -= end_trunc;
         devm_memunmap(dev, (void __force *) pmem->virt_addr);
-        pmem->virt_addr = (void __pmem *) devm_memremap_pages(dev, &nsio->res,
+        pmem->virt_addr = (void __pmem *) devm_memremap_pages(dev, &res,
                         &q->q_usage_counter, altmap);
         pmem->pfn_flags |= PFN_MAP;
         if (IS_ERR(pmem->virt_addr)) {
@@ -438,7 +480,6 @@ static int nvdimm_namespace_attach_pfn(struct nd_namespace_common *ndns)
         }
 
         /* attach pmem disk in "pfn-mode" */
-        pmem->data_offset = offset;
         rc = pmem_attach_disk(dev, ndns, pmem);
         if (rc)
                 goto err;
@@ -447,6 +488,22 @@ static int nvdimm_namespace_attach_pfn(struct nd_namespace_common *ndns)
  err:
         nvdimm_namespace_detach_pfn(ndns);
         return rc;
+
+}
+
+static int nvdimm_namespace_attach_pfn(struct nd_namespace_common *ndns)
+{
+        struct nd_pfn *nd_pfn = to_nd_pfn(ndns->claim);
+        int rc;
+
+        if (!nd_pfn->uuid || !nd_pfn->ndns)
+                return -ENODEV;
+
+        rc = nd_pfn_init(nd_pfn);
+        if (rc)
+                return rc;
+        /* we need a valid pfn_sb before we can init a vmem_altmap */
+        return __nvdimm_namespace_attach_pfn(nd_pfn);
 }
 
 static int nd_pmem_probe(struct device *dev)