x86/dmar: zap DMAR signature for dom0 once in TBOOT case

Commit 6c298ecc1f ("vtd: Reinstate ACPI DMAR on system shutdown or
S3/S4/S5") did everything for acpi_dmar_zap() call to be unnecessary,
except for invoking the function from acpi_parse_dmar(), which
123c779379 ("VTd/dmar: Tweak how the DMAR table is clobbered")
added several years later.

Some stale comments are also removed, No functional change.

Signed-off-by: Zhenzhong Duan <zhenzhong.duan@oracle.com>

diff --git a/xen/arch/x86/tboot.c b/xen/arch/x86/tboot.c
index d5a5292d7ed96639e86c33744e8cac9462bbb2fe..1006f957fb0ca7b0ea6dcf9528026bc26dd73e30 100644 (file)
--- a/xen/arch/x86/tboot.c
+++ b/xen/arch/x86/tboot.c
@@ -461,8 +461,6 @@ int __init tboot_parse_dmar_table(acpi_table_handler dmar_handler)
     if ( txt_heap_base == 0 )
         return 1;
 
-    /* map TXT heap into Xen addr space */
-
     /* walk heap to SinitMleData */
     pa = txt_heap_base;
     /* skip BiosData */
@@ -490,10 +488,6 @@ int __init tboot_parse_dmar_table(acpi_table_handler dmar_handler)
     rc = dmar_handler(dmar_table);
     xfree(dmar_table);
 
-    /* acpi_parse_dmar() zaps APCI DMAR signature in TXT heap table */
-    /* but dom0 will read real table, so must zap it there too */
-    acpi_dmar_zap();
-
     return rc;
 }