nfit/ars: Avoid stale ARS results

commit 78153dd45e7e0596ba32b15d02bda08e1513111e upstream.

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>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/drivers/acpi/nfit/core.c b/drivers/acpi/nfit/core.c
index 4b489d1..925dbc7 100644 (file)
--- a/drivers/acpi/nfit/core.c
+++ b/drivers/acpi/nfit/core.c
@@ -2540,7 +2540,10 @@ 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)
@@ -2633,6 +2636,17 @@ 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
@@ -3117,6 +3131,7 @@ 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 b5fd352..68848fc 100644 (file)
--- a/drivers/acpi/nfit/nfit.h
+++ b/drivers/acpi/nfit/nfit.h
@@ -184,6 +184,7 @@ struct nfit_mem {
 enum scrub_flags {
        ARS_BUSY,
        ARS_CANCEL,
+       ARS_VALID,
        ARS_POLL,
 };