tools/xl: Add altp2m_count parameter

Introduce a new altp2m_count parameter to control the maximum number of altp2m
views a domain can use. By default, if altp2m_count is unspecified and altp2m
is enabled, the value is set to 10, reflecting the legacy behavior.

This change is preparatory; it establishes the groundwork for the feature but
does not activate it.

Signed-off-by: Petr Beneš <w1benny@gmail.com>
Acked-by: Nick Rosbrook <enr0n@ubuntu.com>
Reviewed-by: Anthony PERARD <anthony.perard@vates.tech>

tools/golang/xenlight/helpers.gen.go

@@ -1167,6 +1167,7 @@ if err := x.ArchX86.MsrRelaxed.fromC(&xc.arch_x86.msr_relaxed);err != nil {
 return fmt.Errorf("converting field ArchX86.MsrRelaxed: %v", err)
 }
 x.Altp2M = Altp2MMode(xc.altp2m)
+x.Altp2MCount = uint32(xc.altp2m_count)
 x.VmtraceBufKb = int(xc.vmtrace_buf_kb)
 if err := x.Vpmu.fromC(&xc.vpmu);err != nil {
 return fmt.Errorf("converting field Vpmu: %v", err)
@@ -1701,6 +1702,7 @@ if err := x.ArchX86.MsrRelaxed.toC(&xc.arch_x86.msr_relaxed); err != nil {
 return fmt.Errorf("converting field ArchX86.MsrRelaxed: %v", err)
 }
 xc.altp2m = C.libxl_altp2m_mode(x.Altp2M)
+xc.altp2m_count = C.uint32_t(x.Altp2MCount)
 xc.vmtrace_buf_kb = C.int(x.VmtraceBufKb)
 if err := x.Vpmu.toC(&xc.vpmu); err != nil {
 return fmt.Errorf("converting field Vpmu: %v", err)

tools/golang/xenlight/types.gen.go

@@ -604,6 +604,7 @@ ArchX86 struct {
 MsrRelaxed Defbool
 }
 Altp2M Altp2MMode
+Altp2MCount uint32
 VmtraceBufKb int
 Vpmu Defbool
 TrapUnmappedAccesses Defbool

tools/include/libxl.h

@@ -1257,6 +1257,13 @@ typedef struct libxl__ctx libxl_ctx;
  */
 #define LIBXL_HAVE_ALTP2M 1
 
+/*
+ * LIBXL_HAVE_ALTP2M_COUNT
+ * If this is defined, then libxl supports setting the maximum number of
+ * alternate p2m tables.
+ */
+#define LIBXL_HAVE_ALTP2M_COUNT 1
+
 /*
  * LIBXL_HAVE_REMUS
  * If this is defined, then libxl supports remus.

tools/libs/light/libxl_create.c

@@ -421,6 +421,16 @@ int libxl__domain_build_info_setdefault(libxl__gc *gc,
         return -ERROR_INVAL;
     }
 
+    if (b_info->altp2m_count == LIBXL_ALTP2M_COUNT_DEFAULT) {
+        if (b_info->type == LIBXL_DOMAIN_TYPE_HVM &&
+            (libxl_defbool_val(b_info->u.hvm.altp2m) ||
+            b_info->altp2m != LIBXL_ALTP2M_MODE_DISABLED))
+            /* Reflect the default legacy count */
+            b_info->altp2m_count = 10;
+        else
+            b_info->altp2m_count = 0;
+    }
+
     /* Assume that providing a bootloader user implies enabling restrict. */
     libxl_defbool_setdefault(&b_info->bootloader_restrict,
                              !!b_info->bootloader_user);

tools/libs/light/libxl_internal.h

@@ -111,6 +111,7 @@
 #define LIBXL_MIN_DOM0_MEM (128*1024)
 #define LIBXL_INVALID_GFN (~(uint64_t)0)
 #define LIBXL_VGA_HOLE_SIZE 0x20
+#define LIBXL_ALTP2M_COUNT_DEFAULT (~(uint32_t)0)
 /* use 0 as the domid of the toolstack domain for now */
 #define LIBXL_TOOLSTACK_DOMID 0
 #define QEMU_SIGNATURE "DeviceModelRecord0002"

tools/libs/light/libxl_types.idl

@@ -731,6 +731,7 @@ libxl_domain_build_info = Struct("domain_build_info",[
     # Alternate p2m is not bound to any architecture or guest type, as it is
     # supported by x86 HVM and ARM support is planned.
     ("altp2m", libxl_altp2m_mode),
+    ("altp2m_count", uint32, {'init_val': 'LIBXL_ALTP2M_COUNT_DEFAULT'}),
 
     # Size of preallocated vmtrace trace buffers (in KBYTES).
     # Use zero value to disable this feature.

tools/xl/xl_parse.c

@@ -2099,6 +2099,15 @@ void parse_config_data(const char *config_source,
         }
     }
 
+    if (!xlu_cfg_get_long(config, "altp2m_count", &l, 1)) {
+        if (l != (uint16_t)l) {
+            fprintf(stderr, "ERROR: invalid value %ld for \"altp2m_count\"\n", l);
+            exit (1);
+        }
+
+        b_info->altp2m_count = l;
+    }
+
     if (!xlu_cfg_get_long(config, "vmtrace_buf_kb", &l, 1) && l) {
         b_info->vmtrace_buf_kb = l;
     }