ACPI, APEI, Add WHEA _OSC support

APEI firmware first mode must be turned on explicitly on some
machines, otherwise there may be no GHES hardware error record for
hardware error notification.  APEI bit in generic _OSC call can be
used to do that, but on some machine, a special WHEA _OSC call must be
used.  This patch adds the support to that WHEA _OSC call.

Signed-off-by: Huang Ying <ying.huang@intel.com>
Reviewed-by: Andi Kleen <ak@linux.intel.com>
Reviewed-by: Matthew Garrett <mjg@redhat.com>
Signed-off-by: Len Brown <len.brown@intel.com>
diff --git a/drivers/acpi/apei/apei-base.c b/drivers/acpi/apei/apei-base.c
index 0714194..8041248 100644
--- a/drivers/acpi/apei/apei-base.c
+++ b/drivers/acpi/apei/apei-base.c
@@ -604,3 +604,29 @@
 	return dapei;
 }
 EXPORT_SYMBOL_GPL(apei_get_debugfs_dir);
+
+int apei_osc_setup(void)
+{
+	static u8 whea_uuid_str[] = "ed855e0c-6c90-47bf-a62a-26de0fc5ad5c";
+	acpi_handle handle;
+	u32 capbuf[3];
+	struct acpi_osc_context context = {
+		.uuid_str	= whea_uuid_str,
+		.rev		= 1,
+		.cap.length	= sizeof(capbuf),
+		.cap.pointer	= capbuf,
+	};
+
+	capbuf[OSC_QUERY_TYPE] = OSC_QUERY_ENABLE;
+	capbuf[OSC_SUPPORT_TYPE] = 0;
+	capbuf[OSC_CONTROL_TYPE] = 0;
+
+	if (ACPI_FAILURE(acpi_get_handle(NULL, "\\_SB", &handle))
+	    || ACPI_FAILURE(acpi_run_osc(handle, &context)))
+		return -EIO;
+	else {
+		kfree(context.ret.pointer);
+		return 0;
+	}
+}
+EXPORT_SYMBOL_GPL(apei_osc_setup);
diff --git a/drivers/acpi/apei/apei-internal.h b/drivers/acpi/apei/apei-internal.h
index f286cf7..f57050e 100644
--- a/drivers/acpi/apei/apei-internal.h
+++ b/drivers/acpi/apei/apei-internal.h
@@ -124,4 +124,6 @@
 			const struct acpi_hest_generic_status *estatus);
 int apei_estatus_check_header(const struct acpi_hest_generic_status *estatus);
 int apei_estatus_check(const struct acpi_hest_generic_status *estatus);
+
+int apei_osc_setup(void);
 #endif
diff --git a/drivers/acpi/apei/ghes.c b/drivers/acpi/apei/ghes.c
index b142b94..b1390a6 100644
--- a/drivers/acpi/apei/ghes.c
+++ b/drivers/acpi/apei/ghes.c
@@ -681,6 +681,16 @@
 	if (rc)
 		goto err_ioremap_exit;
 
+	rc = apei_osc_setup();
+	if (rc == 0 && osc_sb_apei_support_acked)
+		pr_info(GHES_PFX "APEI firmware first mode is enabled by APEI bit and WHEA _OSC.\n");
+	else if (rc == 0 && !osc_sb_apei_support_acked)
+		pr_info(GHES_PFX "APEI firmware first mode is enabled by WHEA _OSC.\n");
+	else if (rc && osc_sb_apei_support_acked)
+		pr_info(GHES_PFX "APEI firmware first mode is enabled by APEI bit.\n");
+	else
+		pr_info(GHES_PFX "Failed to enable APEI firmware first mode.\n");
+
 	return 0;
 err_ioremap_exit:
 	ghes_ioremap_exit();