[xen master] tools/ocaml/xc: Fix xc_physinfo() bindings

[patchbot@xxxxxxx]

commit b4642c32c4d079916d5607ddda0232aae5e1690e
Author:     Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
AuthorDate: Thu Jun 8 10:59:37 2023 +0100
Commit:     Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
CommitDate: Fri Jun 9 20:13:22 2023 +0100

    tools/ocaml/xc: Fix xc_physinfo() bindings
    
    The original change doesn't compile on ARM:
    
      xenctrl_stubs.c: In function 'stub_xc_physinfo':
      xenctrl_stubs.c:821:16: error: unused variable 'arch_cap_flags_tag' 
[-Werror=unused-variable]
        821 |         int r, arch_cap_flags_tag;
            |                ^~~~~~~~~~~~~~~~~~
      cc1: all warnings being treated as errors
    
    but it was buggy too.
    
    First, it tried storing an int in a pointer slot, causing heap corruption.
    
    Next, it is not legitimate to exclude arm32 in the toolstack as it 
explicitly
    can operate an arm64 toolstack and build arm64 domains.  That in turn means
    that you can't stash a C uint32_t in an OCaml int.
    
    Rewrite the arch_capabilities handling from scratch.  Break it out into a
    separate function, and make the construction of arch_physinfo_cap_flags 
common
    to prevent other indirection bugs.
    
    Reintroduce arm_physinfo_caps with the fields broken out.
    
    Fixes: 56a7aaa16bfe ("tools: add physinfo arch_capabilities handling for 
Arm")
    Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
    Acked-by: Christian Lindig <christian.lindig@xxxxxxxxx>
---
 tools/ocaml/libs/xc/xenctrl.ml      |  7 ++++-
 tools/ocaml/libs/xc/xenctrl.mli     |  7 ++++-
 tools/ocaml/libs/xc/xenctrl_stubs.c | 52 +++++++++++++++++++++++++------------
 3 files changed, 48 insertions(+), 18 deletions(-)

diff --git a/tools/ocaml/libs/xc/xenctrl.ml b/tools/ocaml/libs/xc/xenctrl.ml
index bf23ca50bb..d6c6eb73db 100644
--- a/tools/ocaml/libs/xc/xenctrl.ml
+++ b/tools/ocaml/libs/xc/xenctrl.ml
@@ -128,10 +128,15 @@ type physinfo_cap_flag =
   | CAP_Gnttab_v1
   | CAP_Gnttab_v2
 
+type arm_physinfo_caps =
+  {
+    sve_vl: int;
+  }
+
 type x86_physinfo_cap_flag
 
 type arch_physinfo_cap_flags =
-  | ARM of int
+  | ARM of arm_physinfo_caps
   | X86 of x86_physinfo_cap_flag list
 
 type physinfo =
diff --git a/tools/ocaml/libs/xc/xenctrl.mli b/tools/ocaml/libs/xc/xenctrl.mli
index ed1e28ea30..3bfc16edba 100644
--- a/tools/ocaml/libs/xc/xenctrl.mli
+++ b/tools/ocaml/libs/xc/xenctrl.mli
@@ -113,10 +113,15 @@ type physinfo_cap_flag =
   | CAP_Gnttab_v1
   | CAP_Gnttab_v2
 
+type arm_physinfo_caps =
+  {
+    sve_vl: int;
+  }
+
 type x86_physinfo_cap_flag
 
 type arch_physinfo_cap_flags =
-  | ARM of int
+  | ARM of arm_physinfo_caps
   | X86 of x86_physinfo_cap_flag list
 
 type physinfo = {
diff --git a/tools/ocaml/libs/xc/xenctrl_stubs.c 
b/tools/ocaml/libs/xc/xenctrl_stubs.c
index a03da31f6f..e4d9070f2d 100644
--- a/tools/ocaml/libs/xc/xenctrl_stubs.c
+++ b/tools/ocaml/libs/xc/xenctrl_stubs.c
@@ -812,13 +812,46 @@ CAMLprim value stub_xc_send_debug_keys(value xch_val, 
value keys)
        CAMLreturn(Val_unit);
 }
 
+CAMLprim value physinfo_arch_caps(const xc_physinfo_t *info)
+{
+       CAMLparam0();
+       CAMLlocal2(arch_cap_flags, arch_obj);
+       int tag = -1;
+
+#if defined(__arm__) || defined(__aarch64__)
+
+       tag = 0; /* tag ARM */
+
+       arch_obj = caml_alloc_tuple(1);
+
+       Store_field(arch_obj, 0,
+                   Val_int(MASK_EXTR(info->arch_capabilities,
+                                     XEN_SYSCTL_PHYSCAP_ARM_SVE_MASK) * 128));
+
+#elif defined(__i386__) || defined(__x86_64__)
+
+       tag = 1; /* tag x86 */
+
+       arch_obj = Tag_cons;
+
+#endif
+
+       if ( tag < 0 )
+               caml_failwith("Unhandled architecture");
+
+       arch_cap_flags = caml_alloc_small(1, tag);
+       Store_field(arch_cap_flags, 0, arch_obj);
+
+       CAMLreturn(arch_cap_flags);
+}
+
 CAMLprim value stub_xc_physinfo(value xch_val)
 {
        CAMLparam1(xch_val);
-       CAMLlocal4(physinfo, cap_list, arch_cap_flags, arch_cap_list);
+       CAMLlocal2(physinfo, cap_list);
        xc_interface *xch = xch_of_val(xch_val);
        xc_physinfo_t c_physinfo;
-       int r, arch_cap_flags_tag;
+       int r;
 
        caml_enter_blocking_section();
        r = xc_physinfo(xch, &c_physinfo);
@@ -846,20 +879,7 @@ CAMLprim value stub_xc_physinfo(value xch_val)
        Store_field(physinfo, 7, caml_copy_nativeint(c_physinfo.scrub_pages));
        Store_field(physinfo, 8, cap_list);
        Store_field(physinfo, 9, Val_int(c_physinfo.max_cpu_id + 1));
-
-#if defined(__i386__) || defined(__x86_64__)
-       arch_cap_list = Tag_cons;
-
-       arch_cap_flags_tag = 1; /* tag x86 */
-
-       arch_cap_flags = caml_alloc_small(1, arch_cap_flags_tag);
-       Store_field(arch_cap_flags, 0, arch_cap_list);
-       Store_field(physinfo, 10, arch_cap_flags);
-#elif defined(__aarch64__)
-       Store_field(physinfo, 10, Val_int(c_physinfo.arch_capabilities));
-#else
-       caml_failwith("Unhandled architecture");
-#endif
+       Store_field(physinfo, 10, physinfo_arch_caps(&c_physinfo));
 
        CAMLreturn(physinfo);
 }
--
generated by git-patchbot for /home/xen/git/xen.git#master