On 07/11/2023 15:22, Vishal Verma wrote:
> Large amounts of memory managed by the kmem driver may come in via CXL,
> and it is often desirable to have the memmap for this memory on the new
> memory itself.
>
> Enroll kmem-managed memory for memmap_on_memory semantics if the dax
> region originates via CXL. For non-CXL dax regions, retain the existing
> default behavior of hot adding without memmap_on_memory semantics.
>
> Cc: Andrew Morton <a...@linux-foundation.org>
> Cc: David Hildenbrand <da...@redhat.com>
> Cc: Michal Hocko <mho...@suse.com>
> Cc: Oscar Salvador <osalva...@suse.de>
> Cc: Dan Williams <dan.j.willi...@intel.com>
> Cc: Dave Jiang <dave.ji...@intel.com>
> Cc: Dave Hansen <dave.han...@linux.intel.com>
> Cc: Huang Ying <ying.hu...@intel.com>
> Reviewed-by: Jonathan Cameron <jonathan.came...@huawei.com>
> Reviewed-by: David Hildenbrand <da...@redhat.com>
> Reviewed-by: "Huang, Ying" <ying.hu...@intel.com>
> Signed-off-by: Vishal Verma <vishal.l.ve...@intel.com>
Tested-by: Li Zhijian <lizhij...@fujitsu.com> # both cxl.kmem and nvdimm.kmem
> ---
> drivers/dax/bus.h | 1 +
> drivers/dax/dax-private.h | 1 +
> drivers/dax/bus.c | 3 +++
> drivers/dax/cxl.c | 1 +
> drivers/dax/hmem/hmem.c | 1 +
> drivers/dax/kmem.c | 8 +++++++-
> drivers/dax/pmem.c | 1 +
> 7 files changed, 15 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/dax/bus.h b/drivers/dax/bus.h
> index 1ccd23360124..cbbf64443098 100644
> --- a/drivers/dax/bus.h
> +++ b/drivers/dax/bus.h
> @@ -23,6 +23,7 @@ struct dev_dax_data {
> struct dev_pagemap *pgmap;
> resource_size_t size;
> int id;
> + bool memmap_on_memory;
> };
>
> struct dev_dax *devm_create_dev_dax(struct dev_dax_data *data);
> diff --git a/drivers/dax/dax-private.h b/drivers/dax/dax-private.h
> index 27cf2daaaa79..446617b73aea 100644
> --- a/drivers/dax/dax-private.h
> +++ b/drivers/dax/dax-private.h
> @@ -70,6 +70,7 @@ struct dev_dax {
> struct ida ida;
> struct device dev;
> struct dev_pagemap *pgmap;
> + bool memmap_on_memory;
> int nr_range;
> struct dev_dax_range {
> unsigned long pgoff;
> diff --git a/drivers/dax/bus.c b/drivers/dax/bus.c
> index 1659b787b65f..1ff1ab5fa105 100644
> --- a/drivers/dax/bus.c
> +++ b/drivers/dax/bus.c
> @@ -367,6 +367,7 @@ static ssize_t create_store(struct device *dev, struct
> device_attribute *attr,
> .dax_region = dax_region,
> .size = 0,
> .id = -1,
> + .memmap_on_memory = false,
> };
> struct dev_dax *dev_dax = devm_create_dev_dax(&data);
>
> @@ -1400,6 +1401,8 @@ struct dev_dax *devm_create_dev_dax(struct dev_dax_data
> *data)
> dev_dax->align = dax_region->align;
> ida_init(&dev_dax->ida);
>
> + dev_dax->memmap_on_memory = data->memmap_on_memory;
> +
> inode = dax_inode(dax_dev);
> dev->devt = inode->i_rdev;
> dev->bus = &dax_bus_type;
> diff --git a/drivers/dax/cxl.c b/drivers/dax/cxl.c
> index 8bc9d04034d6..c696837ab23c 100644
> --- a/drivers/dax/cxl.c
> +++ b/drivers/dax/cxl.c
> @@ -26,6 +26,7 @@ static int cxl_dax_region_probe(struct device *dev)
> .dax_region = dax_region,
> .id = -1,
> .size = range_len(&cxlr_dax->hpa_range),
> + .memmap_on_memory = true,
> };
>
> return PTR_ERR_OR_ZERO(devm_create_dev_dax(&data));
> diff --git a/drivers/dax/hmem/hmem.c b/drivers/dax/hmem/hmem.c
> index 5d2ddef0f8f5..b9da69f92697 100644
> --- a/drivers/dax/hmem/hmem.c
> +++ b/drivers/dax/hmem/hmem.c
> @@ -36,6 +36,7 @@ static int dax_hmem_probe(struct platform_device *pdev)
> .dax_region = dax_region,
> .id = -1,
> .size = region_idle ? 0 : range_len(&mri->range),
> + .memmap_on_memory = false,
> };
>
> return PTR_ERR_OR_ZERO(devm_create_dev_dax(&data));
> diff --git a/drivers/dax/kmem.c b/drivers/dax/kmem.c
> index 369c698b7706..42ee360cf4e3 100644
> --- a/drivers/dax/kmem.c
> +++ b/drivers/dax/kmem.c
> @@ -12,6 +12,7 @@
> #include <linux/mm.h>
> #include <linux/mman.h>
> #include <linux/memory-tiers.h>
> +#include <linux/memory_hotplug.h>
> #include "dax-private.h"
> #include "bus.h"
>
> @@ -93,6 +94,7 @@ static int dev_dax_kmem_probe(struct dev_dax *dev_dax)
> struct dax_kmem_data *data;
> struct memory_dev_type *mtype;
> int i, rc, mapped = 0;
> + mhp_t mhp_flags;
> int numa_node;
> int adist = MEMTIER_DEFAULT_DAX_ADISTANCE;
>
> @@ -179,12 +181,16 @@ static int dev_dax_kmem_probe(struct dev_dax *dev_dax)
> */
> res->flags = IORESOURCE_SYSTEM_RAM;
>
> + mhp_flags = MHP_NID_IS_MGID;
> + if (dev_dax->memmap_on_memory)
> + mhp_flags |= MHP_MEMMAP_ON_MEMORY;
> +
> /*
> * Ensure that future kexec'd kernels will not treat
> * this as RAM automatically.
> */
> rc = add_memory_driver_managed(data->mgid, range.start,
> - range_len(&range), kmem_name, MHP_NID_IS_MGID);
> + range_len(&range), kmem_name, mhp_flags);
>
> if (rc) {
> dev_warn(dev, "mapping%d: %#llx-%#llx memory add
> failed\n",
> diff --git a/drivers/dax/pmem.c b/drivers/dax/pmem.c
> index ae0cb113a5d3..f3c6c67b8412 100644
> --- a/drivers/dax/pmem.c
> +++ b/drivers/dax/pmem.c
> @@ -63,6 +63,7 @@ static struct dev_dax *__dax_pmem_probe(struct device *dev)
> .id = id,
> .pgmap = &pgmap,
> .size = range_len(&range),
> + .memmap_on_memory = false,
> };
>
> return devm_create_dev_dax(&data);
>
