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From: Dan Williams <dan.j.williams@intel.com>
To: akpm@linux-foundation.org
Cc: Joao Martins <joao.m.martins@oracle.com>,
	peterz@infradead.org, vishal.l.verma@intel.com,
	dave.hansen@linux.intel.com, ard.biesheuvel@linaro.org,
	vishal.l.verma@intel.com, linux-mm@kvack.org,
	linux-nvdimm@lists.01.org, joao.m.martins@oracle.com,
	linux-kernel@vger.kernel.org, linux-acpi@vger.kernel.org,
	dri-devel@lists.freedesktop.org
Subject: [PATCH v3 23/23] device-dax: Add a range mapping allocation attribute
Date: Fri, 31 Jul 2020 20:27:06 -0700
Message-ID: <159625242681.3040297.14551750051856153463.stgit@dwillia2-desk3.amr.corp.intel.com> (raw)
In-Reply-To: <159625229779.3040297.11363509688097221416.stgit@dwillia2-desk3.amr.corp.intel.com>

From: Joao Martins <joao.m.martins@oracle.com>

Add a sysfs attribute which denotes a range from the dax region
to be allocated. It's an write only @mapping sysfs attribute in
the format of '<start>-<end>' to allocate a range. @start and
@end use hexadecimal values and the @pgoff is implicitly ordered
wrt to previous writes to @mapping sysfs e.g. a write of a range
of length 1G the pgoff is 0..1G(-4K), a second write will use
@pgoff for 1G+4K..<size>.

This range mapping interface is useful for:

 1) Application which want to implement its own allocation logic,
 and thus pick the desired ranges from dax_region.

 2) For use cases like VMM fast restart[0] where after kexec we
 want to the same gpa<->phys mappings (as originally created
 before kexec).

[0] https://static.sched.com/hosted_files/kvmforum2019/66/VMM-fast-restart_kvmforum2019.pdf

Signed-off-by: Joao Martins <joao.m.martins@oracle.com>
Link: https://lore.kernel.org/r/20200716172913.19658-5-joao.m.martins@oracle.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
---
 drivers/dax/bus.c |   64 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 64 insertions(+)

diff --git a/drivers/dax/bus.c b/drivers/dax/bus.c
index 7a9439132573..aa67555ba183 100644
--- a/drivers/dax/bus.c
+++ b/drivers/dax/bus.c
@@ -1040,6 +1040,67 @@ static ssize_t size_store(struct device *dev, struct device_attribute *attr,
 }
 static DEVICE_ATTR_RW(size);
 
+static ssize_t range_parse(const char *opt, size_t len, struct range *range)
+{
+	unsigned long long addr = 0;
+	char *start, *end, *str;
+	ssize_t rc = EINVAL;
+
+	str = kstrdup(opt, GFP_KERNEL);
+	if (!str)
+		return rc;
+
+	end = str;
+	start = strsep(&end, "-");
+	if (!start || !end)
+		goto err;
+
+	rc = kstrtoull(start, 16, &addr);
+	if (rc)
+		goto err;
+	range->start = addr;
+
+	rc = kstrtoull(end, 16, &addr);
+	if (rc)
+		goto err;
+	range->end = addr;
+
+err:
+	kfree(str);
+	return rc;
+}
+
+static ssize_t mapping_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;
+	size_t to_alloc;
+	struct range r;
+	ssize_t rc;
+
+	rc = range_parse(buf, len, &r);
+	if (rc)
+		return rc;
+
+	rc = -ENXIO;
+	device_lock(dax_region->dev);
+	if (!dax_region->dev->driver) {
+		device_unlock(dax_region->dev);
+		return rc;
+	}
+	device_lock(dev);
+
+	to_alloc = range_len(&r);
+	if (alloc_is_aligned(dev_dax, to_alloc))
+		rc = alloc_dev_dax_range(dev_dax, r.start, to_alloc);
+	device_unlock(dev);
+	device_unlock(dax_region->dev);
+
+	return rc == 0 ? len : rc;
+}
+static DEVICE_ATTR_WO(mapping);
+
 static ssize_t align_show(struct device *dev,
 		struct device_attribute *attr, char *buf)
 {
@@ -1181,6 +1242,8 @@ static umode_t dev_dax_visible(struct kobject *kobj, struct attribute *a, int n)
 		return 0;
 	if (a == &dev_attr_numa_node.attr && !IS_ENABLED(CONFIG_NUMA))
 		return 0;
+	if (a == &dev_attr_mapping.attr && is_static(dax_region))
+		return 0;
 	if ((a == &dev_attr_align.attr ||
 	     a == &dev_attr_size.attr) && is_static(dax_region))
 		return 0444;
@@ -1190,6 +1253,7 @@ static umode_t dev_dax_visible(struct kobject *kobj, struct attribute *a, int n)
 static struct attribute *dev_dax_attributes[] = {
 	&dev_attr_modalias.attr,
 	&dev_attr_size.attr,
+	&dev_attr_mapping.attr,
 	&dev_attr_target_node.attr,
 	&dev_attr_align.attr,
 	&dev_attr_resource.attr,


  parent reply index

Thread overview: 30+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-08-01  3:24 [PATCH v3 00/23] device-dax: Support sub-dividing soft-reserved ranges Dan Williams
2020-08-01  3:25 ` [PATCH v3 01/23] x86/numa: Cleanup configuration dependent command-line options Dan Williams
2020-08-01  3:25 ` [PATCH v3 02/23] x86/numa: Add 'nohmat' option Dan Williams
2020-08-01  3:51   ` Randy Dunlap
2020-08-01 16:36     ` Dan Williams
2020-08-01  3:25 ` [PATCH v3 03/23] efi/fake_mem: Arrange for a resource entry per efi_fake_mem instance Dan Williams
2020-08-01  3:25 ` [PATCH v3 04/23] ACPI: HMAT: Refactor hmat_register_target_device to hmem_register_device Dan Williams
2020-08-01  3:25 ` [PATCH v3 05/23] resource: Report parent to walk_iomem_res_desc() callback Dan Williams
2020-08-01  3:25 ` [PATCH v3 06/23] mm/memory_hotplug: Introduce default phys_to_target_node() implementation Dan Williams
2020-08-01  3:25 ` [PATCH v3 07/23] ACPI: HMAT: Attach a device for each soft-reserved range Dan Williams
2020-08-01  3:25 ` [PATCH v3 08/23] device-dax: Drop the dax_region.pfn_flags attribute Dan Williams
2020-08-01  3:25 ` [PATCH v3 09/23] device-dax: Move instance creation parameters to 'struct dev_dax_data' Dan Williams
2020-08-01  3:25 ` [PATCH v3 10/23] device-dax: Make pgmap optional for instance creation Dan Williams
2020-08-01  3:26 ` [PATCH v3 11/23] device-dax: Kill dax_kmem_res Dan Williams
2020-08-01  3:26 ` [PATCH v3 12/23] device-dax: Add an allocation interface for device-dax instances Dan Williams
2020-08-01  3:26 ` [PATCH v3 13/23] device-dax: Introduce 'seed' devices Dan Williams
2020-08-01  3:26 ` [PATCH v3 14/23] drivers/base: Make device_find_child_by_name() compatible with sysfs inputs Dan Williams
2020-08-01  3:26 ` [PATCH v3 15/23] device-dax: Add resize support Dan Williams
2020-08-01  3:26 ` [PATCH v3 16/23] mm/memremap_pages: Convert to 'struct range' Dan Williams
2020-08-01  3:26 ` [PATCH v3 17/23] mm/memremap_pages: Support multiple ranges per invocation Dan Williams
2020-08-01  3:26 ` [PATCH v3 18/23] device-dax: Add dis-contiguous resource support Dan Williams
2020-08-01  3:26 ` [PATCH v3 19/23] device-dax: Introduce 'mapping' devices Dan Williams
2020-08-01  3:26 ` [PATCH v3 20/23] device-dax: Make align a per-device property Dan Williams
2020-08-01  7:23   ` kernel test robot
2020-08-01  3:26 ` [PATCH v3 21/23] device-dax: Add an 'align' attribute Dan Williams
2020-08-01  6:14   ` kernel test robot
2020-08-01  6:18   ` kernel test robot
2020-08-01  3:27 ` [PATCH v3 22/23] dax/hmem: Introduce dax_hmem.region_idle parameter Dan Williams
2020-08-01  3:27 ` Dan Williams [this message]
2020-08-04 17:02 ` [PATCH v3 00/23] device-dax: Support sub-dividing soft-reserved ranges Jason Gunthorpe

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