[PATCH v2 13/17] x86/CPUID: move bounding of max_{,sub}leaf fields to library code

[Jan Beulich <jbeulich@xxxxxxxx>]

Break out this logic from calculate_host_policy() to also use it in the
x86 emulator harness, where subsequently we'll want to avoid open-coding
AMX maximum palette bounding.

Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
---
v2: New.

--- a/tools/tests/x86_emulator/x86-emulate.c
+++ b/tools/tests/x86_emulator/x86-emulate.c
@@ -79,6 +79,7 @@ bool emul_test_init(void)
     unsigned long sp;
 
     x86_cpuid_policy_fill_native(&cp);
+    x86_cpuid_policy_bound_max_leaves(&cp);
 
     /*
      * The emulator doesn't use these instructions, so can always emulate
@@ -91,6 +92,8 @@ bool emul_test_init(void)
     cp.feat.rdpid = true;
     cp.extd.clzero = true;
 
+    x86_cpuid_policy_shrink_max_leaves(&cp);
+
     if ( cpu_has_xsave )
     {
         unsigned int tmp, ebx;
--- a/xen/arch/x86/cpuid.c
+++ b/xen/arch/x86/cpuid.c
@@ -319,12 +319,7 @@ static void __init calculate_host_policy
 
     *p = raw_cpuid_policy;
 
-    p->basic.max_leaf =
-        min_t(uint32_t, p->basic.max_leaf,   ARRAY_SIZE(p->basic.raw) - 1);
-    p->feat.max_subleaf =
-        min_t(uint32_t, p->feat.max_subleaf, ARRAY_SIZE(p->feat.raw) - 1);
-    p->extd.max_leaf = 0x80000000 | min_t(uint32_t, p->extd.max_leaf & 0xffff,
-                                          ARRAY_SIZE(p->extd.raw) - 1);
+    x86_cpuid_policy_bound_max_leaves(p);
 
     cpuid_featureset_to_policy(boot_cpu_data.x86_capability, p);
     recalculate_xstate(p);
--- a/xen/include/xen/lib/x86/cpuid.h
+++ b/xen/include/xen/lib/x86/cpuid.h
@@ -352,6 +352,12 @@ void x86_cpuid_policy_fill_native(struct
 void x86_cpuid_policy_clear_out_of_range_leaves(struct cpuid_policy *p);
 
 /**
+ * Bound max leaf/subleaf values according to the capacity of the respective
+ * arrays in struct cpuid_policy.
+ */
+void x86_cpuid_policy_bound_max_leaves(struct cpuid_policy *p);
+
+/**
  * Shrink max leaf/subleaf values such that the last respective valid entry
  * isn't all blank.  While permitted by the spec, such extraneous leaves may
  * provide undue "hints" to guests.
--- a/xen/lib/x86/cpuid.c
+++ b/xen/lib/x86/cpuid.c
@@ -238,6 +238,16 @@ void x86_cpuid_policy_clear_out_of_range
                 ARRAY_SIZE(p->extd.raw) - 1);
 }
 
+void x86_cpuid_policy_bound_max_leaves(struct cpuid_policy *p)
+{
+    p->basic.max_leaf =
+        min_t(uint32_t, p->basic.max_leaf, ARRAY_SIZE(p->basic.raw) - 1);
+    p->feat.max_subleaf =
+        min_t(uint32_t, p->feat.max_subleaf, ARRAY_SIZE(p->feat.raw) - 1);
+    p->extd.max_leaf = 0x80000000 | min_t(uint32_t, p->extd.max_leaf & 0xffff,
+                                          ARRAY_SIZE(p->extd.raw) - 1);
+}
+
 void x86_cpuid_policy_shrink_max_leaves(struct cpuid_policy *p)
 {
     unsigned int i;