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@xxxxxxx>
Cc: Rafael J. Wysocki <rjw@xxxxxxxxxxxxx>
Cc: Dan Williams <dan.j.williams@xxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Borislav Petkov <bp@xxxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
drivers/acpi/nfit.c | 48 ++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 48 insertions(+)
diff --git a/drivers/acpi/nfit.c b/drivers/acpi/nfit.c
index 35947ac..d5c78f2 100644
--- 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)
{
@@ -1788,6 +1830,12 @@ 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,
--
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