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device-dax: add a range mapping allocation attribute

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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>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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/159643106970.4062302.10402616567780784722.stgit@dwillia2-desk3.amr.corp.intel.com
Link: https://lore.kernel.org/r/20200716172913.19658-5-joao.m.martins@oracle.com
Link: https://lkml.kernel.org/r/160106119570.30709.4548889722645210610.stgit@dwillia2-desk3.amr.corp.intel.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Joao Martins 2020-10-13 16:51:06 -07:00 committed by Linus Torvalds
parent 5a505603a9
commit 8490e2e25b
1 changed files with 64 additions and 0 deletions
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64
drivers/dax/bus.c
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@ -1043,6 +1043,67 @@ 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)
{
@ -1175,6 +1236,8 @@ 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;
@ -1184,6 +1247,7 @@ 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,