acpi: nfit: Add support for detect platform CPU cache flush on power loss

BugLink: http://bugs.launchpad.net/bugs/1730829
In ACPI 6.2a the platform capability structure has been added to the NFIT
tables. That provides software the ability to determine whether a system
supports the auto flushing of CPU caches on power loss. If the capability
is supported, we do not need to do dax_flush(). Plumbing the path to set the
property on per region from the NFIT tables.

This patch depends on the ACPI NFIT 6.2a platform capabilities support code
in include/acpi/actbl1.h.

Signed-off-by: Dave Jiang <dave.jiang@intel.com>
Reviewed-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Signed-off-by: Ross Zwisler <ross.zwisler@linux.intel.com>
(cherry picked from commit 06e8ccdab15f46dfd31292e2b75d744bc5fc2a7c)
Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>

diff --git a/drivers/acpi/nfit/core.c b/drivers/acpi/nfit/core.c
index b28ce440a06f0879df027e9ea761ddc9adfbb2ab..df702a4bb910e4a9c7956341b014a0f89136b7f2 100644 (file)
--- a/drivers/acpi/nfit/core.c
+++ b/drivers/acpi/nfit/core.c
@@ -838,6 +838,18 @@ static bool add_flush(struct acpi_nfit_desc *acpi_desc,
        return true;
 }
 
+static bool add_platform_cap(struct acpi_nfit_desc *acpi_desc,
+               struct acpi_nfit_capabilities *pcap)
+{
+       struct device *dev = acpi_desc->dev;
+       u32 mask;
+
+       mask = (1 << (pcap->highest_capability + 1)) - 1;
+       acpi_desc->platform_cap = pcap->capabilities & mask;
+       dev_dbg(dev, "%s: cap: %#x\n", __func__, acpi_desc->platform_cap);
+       return true;
+}
+
 static void *add_table(struct acpi_nfit_desc *acpi_desc,
                struct nfit_table_prev *prev, void *table, const void *end)
 {
@@ -883,6 +895,10 @@ static void *add_table(struct acpi_nfit_desc *acpi_desc,
        case ACPI_NFIT_TYPE_SMBIOS:
                dev_dbg(dev, "%s: smbios\n", __func__);
                break;
+       case ACPI_NFIT_TYPE_CAPABILITIES:
+               if (!add_platform_cap(acpi_desc, table))
+                       return err;
+               break;
        default:
                dev_err(dev, "unknown table '%d' parsing nfit\n", hdr->type);
                break;
@@ -2659,6 +2675,9 @@ static int acpi_nfit_register_region(struct acpi_nfit_desc *acpi_desc,
        else
                ndr_desc->numa_node = NUMA_NO_NODE;
 
+       if(acpi_desc->platform_cap & ACPI_NFIT_CAPABILITY_CACHE_FLUSH)
+               set_bit(ND_REGION_PERSIST_CACHE, &ndr_desc->flags);
+
        list_for_each_entry(nfit_memdev, &acpi_desc->memdevs, list) {
                struct acpi_nfit_memory_map *memdev = nfit_memdev->memdev;
                struct nd_mapping_desc *mapping;
@@ -3467,6 +3486,7 @@ static __init int nfit_init(void)
        BUILD_BUG_ON(sizeof(struct acpi_nfit_smbios) != 9);
        BUILD_BUG_ON(sizeof(struct acpi_nfit_control_region) != 80);
        BUILD_BUG_ON(sizeof(struct acpi_nfit_data_region) != 40);
+       BUILD_BUG_ON(sizeof(struct acpi_nfit_capabilities) != 16);
 
        guid_parse(UUID_VOLATILE_MEMORY, &nfit_uuid[NFIT_SPA_VOLATILE]);
        guid_parse(UUID_PERSISTENT_MEMORY, &nfit_uuid[NFIT_SPA_PM]);

diff --git a/drivers/acpi/nfit/nfit.h b/drivers/acpi/nfit/nfit.h
index f0cf18b2da8ba6e8a1e7f6bf3c50929266ec0cae..50d36e166d7011dbc0bcb29ccbd9166c128fc995 100644 (file)
--- a/drivers/acpi/nfit/nfit.h
+++ b/drivers/acpi/nfit/nfit.h
@@ -202,6 +202,7 @@ struct acpi_nfit_desc {
        unsigned long dimm_cmd_force_en;
        unsigned long bus_cmd_force_en;
        unsigned long bus_nfit_cmd_force_en;
+       unsigned int platform_cap;
        int (*blk_do_io)(struct nd_blk_region *ndbr, resource_size_t dpa,
                        void *iobuf, u64 len, int rw);
 };

diff --git a/drivers/nvdimm/pmem.c b/drivers/nvdimm/pmem.c
index 7fbc5c5dc8e176b7fda861f9929ea879bad0406e..8aa542398db4799ebecf8cca6ea5378281bc9abb 100644 (file)
--- a/drivers/nvdimm/pmem.c
+++ b/drivers/nvdimm/pmem.c
@@ -35,6 +35,7 @@
 #include "pmem.h"
 #include "pfn.h"
 #include "nd.h"
+#include "nd-core.h"
 
 static struct device *to_dev(struct pmem_device *pmem)
 {
@@ -334,7 +335,8 @@ static int pmem_attach_disk(struct device *dev,
                dev_warn(dev, "unable to guarantee persistence of writes\n");
                fua = 0;
        }
-       wbc = nvdimm_has_cache(nd_region);
+       wbc = nvdimm_has_cache(nd_region) &&
+               !test_bit(ND_REGION_PERSIST_CACHE, &nd_region->flags);
 
        if (!devm_request_mem_region(dev, res->start, resource_size(res),
                                dev_name(&ndns->dev))) {

diff --git a/include/linux/libnvdimm.h b/include/linux/libnvdimm.h
index f8109ddb5ef1f08e1f0e2140f92d8578df55784c..f2fc0da4da0433c8a03e3db32922f99aadc0ed7e 100644 (file)
--- a/include/linux/libnvdimm.h
+++ b/include/linux/libnvdimm.h
@@ -47,6 +47,11 @@ enum {
 
        /* region flag indicating to direct-map persistent memory by default */
        ND_REGION_PAGEMAP = 0,
+       /*
+        * Platform ensures entire CPU store data path is flushed to pmem on
+        * system power loss.
+        */
+       ND_REGION_PERSIST_CACHE = 1,
 
        /* mark newly adjusted resources as requiring a label update */
        DPA_RESOURCE_ADJUSTED = 1 << 0,