nfit/ars: Avoid stale ARS results

Gate ARS result consumption on whether the OS issued start-ARS since the
previous consumption. The BIOS may only clear its result buffers after a
successful start-ARS.

Fixes: 0caeef63e6d2 ("libnvdimm: Add a poison list and export badblocks")
Cc: <stable@vger.kernel.org>
Reported-by: Krzysztof Rusocki <krzysztof.rusocki@intel.com>
Reported-by: Vishal Verma <vishal.l.verma@intel.com>
Reviewed-by: Toshi Kani <toshi.kani@hpe.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

2 files changed, 17 insertions, 1 deletions

diff --git a/drivers/acpi/nfit/core.c b/drivers/acpi/nfit/core.c
index 629cf91649d2..5c9eb8d700d3 100644
--- a/drivers/acpi/nfit/core.c
+++ b/drivers/acpi/nfit/core.c
@@ -2652,7 +2652,10 @@ static int ars_start(struct acpi_nfit_desc *acpi_desc,
 
         if (rc < 0)
                 return rc;
-        return cmd_rc;
+        if (cmd_rc < 0)
+                return cmd_rc;
+        set_bit(ARS_VALID, &acpi_desc->scrub_flags);
+        return 0;
 }
 
 static int ars_continue(struct acpi_nfit_desc *acpi_desc)
@@ -2745,6 +2748,17 @@ static int ars_status_process_records(struct acpi_nfit_desc *acpi_desc)
          */
         if (ars_status->out_length < 44)
                 return 0;
+
+        /*
+         * Ignore potentially stale results that are only refreshed
+         * after a start-ARS event.
+         */
+        if (!test_and_clear_bit(ARS_VALID, &acpi_desc->scrub_flags)) {
+                dev_dbg(acpi_desc->dev, "skip %d stale records\n",
+                                ars_status->num_records);
+                return 0;
+        }
+
         for (i = 0; i < ars_status->num_records; i++) {
                 /* only process full records */
                 if (ars_status->out_length
@@ -3229,6 +3243,7 @@ static int acpi_nfit_register_regions(struct acpi_nfit_desc *acpi_desc)
         struct nfit_spa *nfit_spa;
         int rc;
 
+        set_bit(ARS_VALID, &acpi_desc->scrub_flags);
         list_for_each_entry(nfit_spa, &acpi_desc->spas, list) {
                 switch (nfit_spa_type(nfit_spa->spa)) {
                 case NFIT_SPA_VOLATILE:
diff --git a/drivers/acpi/nfit/nfit.h b/drivers/acpi/nfit/nfit.h
index d14bad687fb8..0cbe5009eb2c 100644
--- a/drivers/acpi/nfit/nfit.h
+++ b/drivers/acpi/nfit/nfit.h
@@ -213,6 +213,7 @@ struct nfit_mem {
 enum scrub_flags {
         ARS_BUSY,
         ARS_CANCEL,
+        ARS_VALID,
         ARS_POLL,
 };