device-dax: introduce 'mapping' devices

In support of interrogating the physical address layout of a device with
dis-contiguous ranges, introduce a sysfs directory with 'start', 'end',
and 'page_offset' attributes.  The alternative is trying to parse
/proc/iomem, and that file will not reflect the extent layout until the
device is enabled.

Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Joao Martins <joao.m.martins@oracle.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Ard Biesheuvel <ardb@kernel.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Ben Skeggs <bskeggs@redhat.com>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Brice Goglin <Brice.Goglin@inria.fr>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Dave Jiang <dave.jiang@intel.com>
Cc: David Airlie <airlied@linux.ie>
Cc: David Hildenbrand <david@redhat.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Hulk Robot <hulkci@huawei.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Ira Weiny <ira.weiny@intel.com>
Cc: Jason Gunthorpe <jgg@mellanox.com>
Cc: Jason Yan <yanaijie@huawei.com>
Cc: Jeff Moyer <jmoyer@redhat.com>
Cc: "Jérôme Glisse" <jglisse@redhat.com>
Cc: Jia He <justin.he@arm.com>
Cc: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: kernel test robot <lkp@intel.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Mike Rapoport <rppt@linux.ibm.com>
Cc: Paul Mackerras <paulus@ozlabs.org>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: "Rafael J. Wysocki" <rafael.j.wysocki@intel.com>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Stefano Stabellini <sstabellini@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tom Lendacky <thomas.lendacky@amd.com>
Cc: Vishal Verma <vishal.l.verma@intel.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: Wei Yang <richard.weiyang@linux.alibaba.com>
Cc: Will Deacon <will@kernel.org>
Link: https://lkml.kernel.org/r/159643104819.4062302.13691281391423291589.stgit@dwillia2-desk3.amr.corp.intel.com
Link: https://lkml.kernel.org/r/160106117446.30709.2751020815463722537.stgit@dwillia2-desk3.amr.corp.intel.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/drivers/dax/bus.c b/drivers/dax/bus.c
index 06a789a..005fa3e 100644 (file)
--- a/drivers/dax/bus.c
+++ b/drivers/dax/bus.c
@@ -579,6 +579,167 @@ struct dax_region *alloc_dax_region(struct device *parent, int region_id,
 }
 EXPORT_SYMBOL_GPL(alloc_dax_region);
 
+static void dax_mapping_release(struct device *dev)
+{
+       struct dax_mapping *mapping = to_dax_mapping(dev);
+       struct dev_dax *dev_dax = to_dev_dax(dev->parent);
+
+       ida_free(&dev_dax->ida, mapping->id);
+       kfree(mapping);
+}
+
+static void unregister_dax_mapping(void *data)
+{
+       struct device *dev = data;
+       struct dax_mapping *mapping = to_dax_mapping(dev);
+       struct dev_dax *dev_dax = to_dev_dax(dev->parent);
+       struct dax_region *dax_region = dev_dax->region;
+
+       dev_dbg(dev, "%s\n", __func__);
+
+       device_lock_assert(dax_region->dev);
+
+       dev_dax->ranges[mapping->range_id].mapping = NULL;
+       mapping->range_id = -1;
+
+       device_del(dev);
+       put_device(dev);
+}
+
+static struct dev_dax_range *get_dax_range(struct device *dev)
+{
+       struct dax_mapping *mapping = to_dax_mapping(dev);
+       struct dev_dax *dev_dax = to_dev_dax(dev->parent);
+       struct dax_region *dax_region = dev_dax->region;
+
+       device_lock(dax_region->dev);
+       if (mapping->range_id < 0) {
+               device_unlock(dax_region->dev);
+               return NULL;
+       }
+
+       return &dev_dax->ranges[mapping->range_id];
+}
+
+static void put_dax_range(struct dev_dax_range *dax_range)
+{
+       struct dax_mapping *mapping = dax_range->mapping;
+       struct dev_dax *dev_dax = to_dev_dax(mapping->dev.parent);
+       struct dax_region *dax_region = dev_dax->region;
+
+       device_unlock(dax_region->dev);
+}
+
+static ssize_t start_show(struct device *dev,
+               struct device_attribute *attr, char *buf)
+{
+       struct dev_dax_range *dax_range;
+       ssize_t rc;
+
+       dax_range = get_dax_range(dev);
+       if (!dax_range)
+               return -ENXIO;
+       rc = sprintf(buf, "%#llx\n", dax_range->range.start);
+       put_dax_range(dax_range);
+
+       return rc;
+}
+static DEVICE_ATTR(start, 0400, start_show, NULL);
+
+static ssize_t end_show(struct device *dev,
+               struct device_attribute *attr, char *buf)
+{
+       struct dev_dax_range *dax_range;
+       ssize_t rc;
+
+       dax_range = get_dax_range(dev);
+       if (!dax_range)
+               return -ENXIO;
+       rc = sprintf(buf, "%#llx\n", dax_range->range.end);
+       put_dax_range(dax_range);
+
+       return rc;
+}
+static DEVICE_ATTR(end, 0400, end_show, NULL);
+
+static ssize_t pgoff_show(struct device *dev,
+               struct device_attribute *attr, char *buf)
+{
+       struct dev_dax_range *dax_range;
+       ssize_t rc;
+
+       dax_range = get_dax_range(dev);
+       if (!dax_range)
+               return -ENXIO;
+       rc = sprintf(buf, "%#lx\n", dax_range->pgoff);
+       put_dax_range(dax_range);
+
+       return rc;
+}
+static DEVICE_ATTR(page_offset, 0400, pgoff_show, NULL);
+
+static struct attribute *dax_mapping_attributes[] = {
+       &dev_attr_start.attr,
+       &dev_attr_end.attr,
+       &dev_attr_page_offset.attr,
+       NULL,
+};
+
+static const struct attribute_group dax_mapping_attribute_group = {
+       .attrs = dax_mapping_attributes,
+};
+
+static const struct attribute_group *dax_mapping_attribute_groups[] = {
+       &dax_mapping_attribute_group,
+       NULL,
+};
+
+static struct device_type dax_mapping_type = {
+       .release = dax_mapping_release,
+       .groups = dax_mapping_attribute_groups,
+};
+
+static int devm_register_dax_mapping(struct dev_dax *dev_dax, int range_id)
+{
+       struct dax_region *dax_region = dev_dax->region;
+       struct dax_mapping *mapping;
+       struct device *dev;
+       int rc;
+
+       device_lock_assert(dax_region->dev);
+
+       if (dev_WARN_ONCE(&dev_dax->dev, !dax_region->dev->driver,
+                               "region disabled\n"))
+               return -ENXIO;
+
+       mapping = kzalloc(sizeof(*mapping), GFP_KERNEL);
+       if (!mapping)
+               return -ENOMEM;
+       mapping->range_id = range_id;
+       mapping->id = ida_alloc(&dev_dax->ida, GFP_KERNEL);
+       if (mapping->id < 0) {
+               kfree(mapping);
+               return -ENOMEM;
+       }
+       dev_dax->ranges[range_id].mapping = mapping;
+       dev = &mapping->dev;
+       device_initialize(dev);
+       dev->parent = &dev_dax->dev;
+       dev->type = &dax_mapping_type;
+       dev_set_name(dev, "mapping%d", mapping->id);
+       rc = device_add(dev);
+       if (rc) {
+               put_device(dev);
+               return rc;
+       }
+
+       rc = devm_add_action_or_reset(dax_region->dev, unregister_dax_mapping,
+                       dev);
+       if (rc)
+               return rc;
+       return 0;
+}
+
 static int alloc_dev_dax_range(struct dev_dax *dev_dax, u64 start,
                resource_size_t size)
 {
@@ -588,7 +749,7 @@ static int alloc_dev_dax_range(struct dev_dax *dev_dax, u64 start,
        struct dev_dax_range *ranges;
        unsigned long pgoff = 0;
        struct resource *alloc;
-       int i;
+       int i, rc;
 
        device_lock_assert(dax_region->dev);
 
@@ -633,6 +794,22 @@ static int alloc_dev_dax_range(struct dev_dax *dev_dax, u64 start,
 
        dev_dbg(dev, "alloc range[%d]: %pa:%pa\n", dev_dax->nr_range - 1,
                        &alloc->start, &alloc->end);
+       /*
+        * A dev_dax instance must be registered before mapping device
+        * children can be added. Defer to devm_create_dev_dax() to add
+        * the initial mapping device.
+        */
+       if (!device_is_registered(&dev_dax->dev))
+               return 0;
+
+       rc = devm_register_dax_mapping(dev_dax, dev_dax->nr_range - 1);
+       if (rc) {
+               dev_dbg(dev, "delete range[%d]: %pa:%pa\n", dev_dax->nr_range - 1,
+                               &alloc->start, &alloc->end);
+               dev_dax->nr_range--;
+               __release_region(res, alloc->start, resource_size(alloc));
+               return rc;
+       }
 
        return 0;
 }
@@ -701,11 +878,14 @@ static int dev_dax_shrink(struct dev_dax *dev_dax, resource_size_t size)
 
        for (i = dev_dax->nr_range - 1; i >= 0; i--) {
                struct range *range = &dev_dax->ranges[i].range;
+               struct dax_mapping *mapping = dev_dax->ranges[i].mapping;
                struct resource *adjust = NULL, *res;
                resource_size_t shrink;
 
                shrink = min_t(u64, to_shrink, range_len(range));
                if (shrink >= range_len(range)) {
+                       devm_release_action(dax_region->dev,
+                                       unregister_dax_mapping, &mapping->dev);
                        __release_region(&dax_region->res, range->start,
                                        range_len(range));
                        dev_dax->nr_range--;
@@ -1036,9 +1216,9 @@ struct dev_dax *devm_create_dev_dax(struct dev_dax_data *data)
        /* a device_dax instance is dead while the driver is not attached */
        kill_dax(dax_dev);
 
-       /* from here on we're committed to teardown via dev_dax_release() */
        dev_dax->dax_dev = dax_dev;
        dev_dax->target_node = dax_region->target_node;
+       ida_init(&dev_dax->ida);
        kref_get(&dax_region->kref);
 
        inode = dax_inode(dax_dev);
@@ -1061,6 +1241,13 @@ struct dev_dax *devm_create_dev_dax(struct dev_dax_data *data)
        if (rc)
                return ERR_PTR(rc);
 
+       /* register mapping device for the initial allocation range */
+       if (dev_dax->nr_range && range_len(&dev_dax->ranges[0].range)) {
+               rc = devm_register_dax_mapping(dev_dax, 0);
+               if (rc)
+                       return ERR_PTR(rc);
+       }
+
        return dev_dax;
 
 err_alloc_dax:

diff --git a/drivers/dax/dax-private.h b/drivers/dax/dax-private.h
index f863287..13780f6 100644 (file)
--- a/drivers/dax/dax-private.h
+++ b/drivers/dax/dax-private.h
@@ -40,6 +40,12 @@ struct dax_region {
        struct device *youngest;
 };
 
+struct dax_mapping {
+       struct device dev;
+       int range_id;
+       int id;
+};
+
 /**
  * struct dev_dax - instance data for a subdivision of a dax region, and
  * data while the device is activated in the driver.
@@ -47,6 +53,7 @@ struct dax_region {
  * @dax_dev - core dax functionality
  * @target_node: effective numa node if dev_dax memory range is onlined
  * @id: ida allocated id
+ * @ida: mapping id allocator
  * @dev - device core
  * @pgmap - pgmap for memmap setup / lifetime (driver owned)
  * @nr_range: size of @ranges
@@ -57,12 +64,14 @@ struct dev_dax {
        struct dax_device *dax_dev;
        int target_node;
        int id;
+       struct ida ida;
        struct device dev;
        struct dev_pagemap *pgmap;
        int nr_range;
        struct dev_dax_range {
                unsigned long pgoff;
                struct range range;
+               struct dax_mapping *mapping;
        } *ranges;
 };
 
@@ -70,4 +79,9 @@ static inline struct dev_dax *to_dev_dax(struct device *dev)
 {
        return container_of(dev, struct dev_dax, dev);
 }
+
+static inline struct dax_mapping *to_dax_mapping(struct device *dev)
+{
+       return container_of(dev, struct dax_mapping, dev);
+}
 #endif