ACPI: Change NFIT driver to insert new resource

ACPI 6 defines persistent memory (PMEM) ranges in multiple
firmware interfaces, e820, EFI, and ACPI NFIT table.  This EFI
change, however, leads to hit a bug in the grub bootloader, which
treats EFI_PERSISTENT_MEMORY type as regular memory and corrupts
stored user data [1].

Therefore, BIOS may set generic reserved type in e820 and EFI to
cover PMEM ranges.  The kernel can initialize PMEM ranges from
ACPI NFIT table alone.

This scheme causes a problem in the iomem table, though.  On x86,
for instance, e820_reserve_resources() initializes top-level entries
(iomem_resource.child) from the e820 table at early boot-time.
This creates "reserved" entry for a PMEM range, which does not allow
region_intersects() to check with PMEM type.

Change acpi_nfit_register_region() to call acpi_nfit_insert_resource(),
which calls insert_resource() to insert a PMEM entry from NFIT when
the iomem table does not have a PMEM entry already.  That is, when
a PMEM range is marked as reserved type in e820, it inserts
"Persistent Memory" entry, which results as follows.

 + "Persistent Memory"
    + "reserved"

This allows the EINJ driver, which calls region_intersects() to check
PMEM ranges, to work continuously even if BIOS sets reserved type
(or sets nothing) to PMEM ranges in e820 and EFI.

[1]: https://lists.gnu.org/archive/html/grub-devel/2015-11/msg00209.html
Signed-off-by: Toshi Kani <toshi.kani@hpe.com>
Cc: Rafael J. Wysocki <rjw@rjwysocki.net>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Borislav Petkov <bp@suse.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

diff --git a/drivers/acpi/nfit.c b/drivers/acpi/nfit.c
index fb53db1..269de5f 100644 (file)
--- a/drivers/acpi/nfit.c
+++ b/drivers/acpi/nfit.c
@@ -1571,6 +1571,48 @@ static int ars_status_process_records(struct nvdimm_bus *nvdimm_bus,
        return 0;
 }
 
+static void acpi_nfit_remove_resource(void *data)
+{
+       struct resource *res = data;
+
+       remove_resource(res);
+}
+
+static int acpi_nfit_insert_resource(struct acpi_nfit_desc *acpi_desc,
+               struct nd_region_desc *ndr_desc)
+{
+       struct resource *res, *nd_res = ndr_desc->res;
+       int is_pmem, ret;
+
+       /* No operation if the region is already registered as PMEM */
+       is_pmem = region_intersects(nd_res->start, resource_size(nd_res),
+                               IORESOURCE_MEM, IORES_DESC_PERSISTENT_MEMORY);
+       if (is_pmem == REGION_INTERSECTS)
+               return 0;
+
+       res = devm_kzalloc(acpi_desc->dev, sizeof(*res), GFP_KERNEL);
+       if (!res)
+               return -ENOMEM;
+
+       res->name = "Persistent Memory";
+       res->start = nd_res->start;
+       res->end = nd_res->end;
+       res->flags = IORESOURCE_MEM;
+       res->desc = IORES_DESC_PERSISTENT_MEMORY;
+
+       ret = insert_resource(&iomem_resource, res);
+       if (ret)
+               return ret;
+
+       ret = devm_add_action(acpi_desc->dev, acpi_nfit_remove_resource, res);
+       if (ret) {
+               remove_resource(res);
+               return ret;
+       }
+
+       return 0;
+}
+
 static int acpi_nfit_find_poison(struct acpi_nfit_desc *acpi_desc,
                struct nd_region_desc *ndr_desc)
 {
@@ -1781,6 +1823,12 @@ static int acpi_nfit_register_region(struct acpi_nfit_desc *acpi_desc,
 
        nvdimm_bus = acpi_desc->nvdimm_bus;
        if (nfit_spa_type(spa) == NFIT_SPA_PM) {
+               rc = acpi_nfit_insert_resource(acpi_desc, ndr_desc);
+               if (rc)
+                       dev_warn(acpi_desc->dev,
+                               "failed to insert pmem resource to iomem: %d\n",
+                               rc);
+
                rc = acpi_nfit_find_poison(acpi_desc, ndr_desc);
                if (rc) {
                        dev_err(acpi_desc->dev,