Commit af1996ef authored Mar 09, 2016 by Toshi Kani Committed by Dan Williams Mar 09, 2016

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>

parent 8095d0f2

drivers/acpi/nfit.c

+48 −0

Original line number	Diff line number	Diff line
		@@ -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,

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