acpi nvdimm: fix wrong buffer size returned by DSM method

Currently, 'RLEN' is the totally buffer size written by QEMU and it is
ACPI internally used only. The buffer size returned to guest should
not include 'RLEN' itself

Signed-off-by: Xiao Guangrong <guangrong.xiao@linux.intel.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

diff --git a/hw/acpi/nvdimm.c b/hw/acpi/nvdimm.c
index e486128aa1b584ce6bcf10f4ae3fe3104dde8bbd..24a2b3b78a7752a25850d5d9bf3849b85d7d02dd 100644 (file)
--- a/hw/acpi/nvdimm.c
+++ b/hw/acpi/nvdimm.c
@@ -862,7 +862,8 @@ static void nvdimm_build_common_dsm(Aml *dev)
     aml_append(method, aml_store(dsm_mem, aml_name("NTFI")));
 
     result_size = aml_local(1);
-    aml_append(method, aml_store(aml_name("RLEN"), result_size));
+    /* RLEN is not included in the payload returned to guest. */
+    aml_append(method, aml_subtract(aml_name("RLEN"), aml_int(4), result_size));
     aml_append(method, aml_store(aml_shiftleft(result_size, aml_int(3)),
                                  result_size));
     aml_append(method, aml_create_field(aml_name("ODAT"), aml_int(0),