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authorDan Williams <dan.j.williams@intel.com>2020-10-13 16:50:39 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2020-10-13 18:38:28 -0700
commit60e93dc097f7f13a16a7e4b75b8803eb2adbb721 (patch)
tree166d2cb97be818cee8550a668ec14eecc2f0ec33 /drivers/dax/kmem.c
parentb7b3c01b191596d27a6980d1a42504f5b607f802 (diff)
device-dax: add dis-contiguous resource support
Break the requirement that device-dax instances are physically contiguous. With this constraint removed it allows fragmented available capacity to be fully allocated. This capability is useful to mitigate the "noisy neighbor" problem with memory-side-cache management for virtual machines, or any other scenario where a platform address boundary also designates a performance boundary. For example a direct mapped memory side cache might rotate cache colors at 1GB boundaries. With dis-contiguous allocations a device-dax instance could be configured to contain only 1 cache color. It also satisfies Joao's use case (see link) for partitioning memory for exclusive guest access. It allows for a future potential mode where the host kernel need not allocate 'struct page' capacity up-front. Reported-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://lore.kernel.org/lkml/20200110190313.17144-1-joao.m.martins@oracle.com/ Link: https://lkml.kernel.org/r/159643104304.4062302.16561669534797528660.stgit@dwillia2-desk3.amr.corp.intel.com Link: https://lkml.kernel.org/r/160106116875.30709.11456649969327399771.stgit@dwillia2-desk3.amr.corp.intel.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'drivers/dax/kmem.c')
-rw-r--r--drivers/dax/kmem.c130
1 files changed, 87 insertions, 43 deletions
diff --git a/drivers/dax/kmem.c b/drivers/dax/kmem.c
index c2ac465cc342..6c933f2b604e 100644
--- a/drivers/dax/kmem.c
+++ b/drivers/dax/kmem.c
@@ -19,24 +19,28 @@ static const char *kmem_name;
/* Set if any memory will remain added when the driver will be unloaded. */
static bool any_hotremove_failed;
-static struct range dax_kmem_range(struct dev_dax *dev_dax)
+static int dax_kmem_range(struct dev_dax *dev_dax, int i, struct range *r)
{
- struct range range;
+ struct dev_dax_range *dax_range = &dev_dax->ranges[i];
+ struct range *range = &dax_range->range;
/* memory-block align the hotplug range */
- range.start = ALIGN(dev_dax->range.start, memory_block_size_bytes());
- range.end = ALIGN_DOWN(dev_dax->range.end + 1, memory_block_size_bytes()) - 1;
- return range;
+ r->start = ALIGN(range->start, memory_block_size_bytes());
+ r->end = ALIGN_DOWN(range->end + 1, memory_block_size_bytes()) - 1;
+ if (r->start >= r->end) {
+ r->start = range->start;
+ r->end = range->end;
+ return -ENOSPC;
+ }
+ return 0;
}
static int dev_dax_kmem_probe(struct dev_dax *dev_dax)
{
- struct range range = dax_kmem_range(dev_dax);
struct device *dev = &dev_dax->dev;
- struct resource *res;
+ int i, mapped = 0;
char *res_name;
int numa_node;
- int rc;
/*
* Ensure good NUMA information for the persistent memory.
@@ -55,31 +59,58 @@ static int dev_dax_kmem_probe(struct dev_dax *dev_dax)
if (!res_name)
return -ENOMEM;
- /* Region is permanently reserved if hotremove fails. */
- res = request_mem_region(range.start, range_len(&range), res_name);
- if (!res) {
- dev_warn(dev, "could not reserve region [%#llx-%#llx]\n", range.start, range.end);
- kfree(res_name);
- return -EBUSY;
- }
-
- /*
- * Set flags appropriate for System RAM. Leave ..._BUSY clear
- * so that add_memory() can add a child resource. Do not
- * inherit flags from the parent since it may set new flags
- * unknown to us that will break add_memory() below.
- */
- res->flags = IORESOURCE_SYSTEM_RAM;
-
- /*
- * Ensure that future kexec'd kernels will not treat this as RAM
- * automatically.
- */
- rc = add_memory_driver_managed(numa_node, range.start, range_len(&range), kmem_name);
- if (rc) {
- release_mem_region(range.start, range_len(&range));
- kfree(res_name);
- return rc;
+ for (i = 0; i < dev_dax->nr_range; i++) {
+ struct resource *res;
+ struct range range;
+ int rc;
+
+ rc = dax_kmem_range(dev_dax, i, &range);
+ if (rc) {
+ dev_info(dev, "mapping%d: %#llx-%#llx too small after alignment\n",
+ i, range.start, range.end);
+ continue;
+ }
+
+ /* Region is permanently reserved if hotremove fails. */
+ res = request_mem_region(range.start, range_len(&range), res_name);
+ if (!res) {
+ dev_warn(dev, "mapping%d: %#llx-%#llx could not reserve region\n",
+ i, range.start, range.end);
+ /*
+ * Once some memory has been onlined we can't
+ * assume that it can be un-onlined safely.
+ */
+ if (mapped)
+ continue;
+ kfree(res_name);
+ return -EBUSY;
+ }
+
+ /*
+ * Set flags appropriate for System RAM. Leave ..._BUSY clear
+ * so that add_memory() can add a child resource. Do not
+ * inherit flags from the parent since it may set new flags
+ * unknown to us that will break add_memory() below.
+ */
+ res->flags = IORESOURCE_SYSTEM_RAM;
+
+ /*
+ * Ensure that future kexec'd kernels will not treat
+ * this as RAM automatically.
+ */
+ rc = add_memory_driver_managed(numa_node, range.start,
+ range_len(&range), kmem_name);
+
+ if (rc) {
+ dev_warn(dev, "mapping%d: %#llx-%#llx memory add failed\n",
+ i, range.start, range.end);
+ release_mem_region(range.start, range_len(&range));
+ if (mapped)
+ continue;
+ kfree(res_name);
+ return rc;
+ }
+ mapped++;
}
dev_set_drvdata(dev, res_name);
@@ -90,9 +121,8 @@ static int dev_dax_kmem_probe(struct dev_dax *dev_dax)
#ifdef CONFIG_MEMORY_HOTREMOVE
static int dev_dax_kmem_remove(struct dev_dax *dev_dax)
{
- int rc;
+ int i, success = 0;
struct device *dev = &dev_dax->dev;
- struct range range = dax_kmem_range(dev_dax);
const char *res_name = dev_get_drvdata(dev);
/*
@@ -101,17 +131,31 @@ static int dev_dax_kmem_remove(struct dev_dax *dev_dax)
* there is no way to hotremove this memory until reboot because device
* unbind will succeed even if we return failure.
*/
- rc = remove_memory(dev_dax->target_node, range.start, range_len(&range));
- if (rc) {
+ for (i = 0; i < dev_dax->nr_range; i++) {
+ struct range range;
+ int rc;
+
+ rc = dax_kmem_range(dev_dax, i, &range);
+ if (rc)
+ continue;
+
+ rc = remove_memory(dev_dax->target_node, range.start,
+ range_len(&range));
+ if (rc == 0) {
+ release_mem_region(range.start, range_len(&range));
+ success++;
+ continue;
+ }
any_hotremove_failed = true;
- dev_err(dev, "%#llx-%#llx cannot be hotremoved until the next reboot\n",
- range.start, range.end);
- return rc;
+ dev_err(dev,
+ "mapping%d: %#llx-%#llx cannot be hotremoved until the next reboot\n",
+ i, range.start, range.end);
}
- /* Release and free dax resources */
- release_mem_region(range.start, range_len(&range));
- kfree(res_name);
+ if (success >= dev_dax->nr_range) {
+ kfree(res_name);
+ dev_set_drvdata(dev, NULL);
+ }
return 0;
}