libxg: don't use max policy in xc_cpuid_xend_policy()

using max undermines the separation between default and max. For
example, turning off AVX512F on an MPX-capable system silently turns on
MPX, despite this not being part of the default policy anymore. Since
the information is used only for determining what to convert 'x' to (but
not to e.g. validate '1' settings), the effect of this change is
identical for guests with (suitable) "cpuid=" settings to that of the
changes separating default from max and then converting (e.g.) MPX from
being part of default to only being part of max for guests without
(affected) "cpuid=" settings.

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Andrew Cooper <andrew.cooper3@citrix.com>

diff --git a/tools/libs/guest/xg_cpuid_x86.c b/tools/libs/guest/xg_cpuid_x86.c
index aae6931a11482a7649adcd17aa3c6a84961b43dc..5ea69ad3d51ab68f62b9ccb5f05e1455236d13f5 100644 (file)
--- a/tools/libs/guest/xg_cpuid_x86.c
+++ b/tools/libs/guest/xg_cpuid_x86.c
@@ -288,11 +288,11 @@ static int xc_cpuid_xend_policy(
     unsigned int nr_leaves, nr_msrs;
     uint32_t err_leaf = -1, err_subleaf = -1, err_msr = -1;
     /*
-     * Three full policies.  The host, domain max, and domain current for the
-     * domain type.
+     * Three full policies.  The host, default for the domain type,
+     * and domain current.
      */
-    xen_cpuid_leaf_t *host = NULL, *max = NULL, *cur = NULL;
-    unsigned int nr_host, nr_max, nr_cur;
+    xen_cpuid_leaf_t *host = NULL, *def = NULL, *cur = NULL;
+    unsigned int nr_host, nr_def, nr_cur;
 
     if ( xc_domain_getinfo(xch, domid, 1, &di) != 1 ||
          di.domid != domid )
@@ -312,7 +312,7 @@ static int xc_cpuid_xend_policy(
 
     rc = -ENOMEM;
     if ( (host = calloc(nr_leaves, sizeof(*host))) == NULL ||
-         (max  = calloc(nr_leaves, sizeof(*max)))  == NULL ||
+         (def  = calloc(nr_leaves, sizeof(*def)))  == NULL ||
          (cur  = calloc(nr_leaves, sizeof(*cur)))  == NULL )
     {
         ERROR("Unable to allocate memory for %u CPUID leaves", nr_leaves);
@@ -330,15 +330,16 @@ static int xc_cpuid_xend_policy(
         goto fail;
     }
 
-    /* Get the domain's max policy. */
+    /* Get the domain type's default policy. */
     nr_msrs = 0;
-    nr_max = nr_leaves;
-    rc = xc_get_system_cpu_policy(xch, di.hvm ? XEN_SYSCTL_cpu_policy_hvm_max
-                                              : XEN_SYSCTL_cpu_policy_pv_max,
-                                  &nr_max, max, &nr_msrs, NULL);
+    nr_def = nr_leaves;
+    rc = xc_get_system_cpu_policy(xch,
+                                  di.hvm ? XEN_SYSCTL_cpu_policy_hvm_default
+                                         : XEN_SYSCTL_cpu_policy_pv_default,
+                                  &nr_def, def, &nr_msrs, NULL);
     if ( rc )
     {
-        PERROR("Failed to obtain %s max policy", di.hvm ? "hvm" : "pv");
+        PERROR("Failed to obtain %s def policy", di.hvm ? "hvm" : "pv");
         rc = -errno;
         goto fail;
     }
@@ -359,10 +360,10 @@ static int xc_cpuid_xend_policy(
     for ( ; xend->leaf != XEN_CPUID_INPUT_UNUSED; ++xend )
     {
         xen_cpuid_leaf_t *cur_leaf = find_leaf(cur, nr_cur, xend);
-        const xen_cpuid_leaf_t *max_leaf = find_leaf(max, nr_max, xend);
+        const xen_cpuid_leaf_t *def_leaf = find_leaf(def, nr_def, xend);
         const xen_cpuid_leaf_t *host_leaf = find_leaf(host, nr_host, xend);
 
-        if ( cur_leaf == NULL || max_leaf == NULL || host_leaf == NULL )
+        if ( cur_leaf == NULL || def_leaf == NULL || host_leaf == NULL )
         {
             ERROR("Missing leaf %#x, subleaf %#x", xend->leaf, xend->subleaf);
             goto fail;
@@ -371,7 +372,7 @@ static int xc_cpuid_xend_policy(
         for ( unsigned int i = 0; i < ARRAY_SIZE(xend->policy); i++ )
         {
             uint32_t *cur_reg = &cur_leaf->a + i;
-            const uint32_t *max_reg = &max_leaf->a + i;
+            const uint32_t *def_reg = &def_leaf->a + i;
             const uint32_t *host_reg = &host_leaf->a + i;
 
             if ( xend->policy[i] == NULL )
@@ -386,7 +387,7 @@ static int xc_cpuid_xend_policy(
                 else if ( xend->policy[i][j] == '0' )
                     val = false;
                 else if ( xend->policy[i][j] == 'x' )
-                    val = test_bit(31 - j, max_reg);
+                    val = test_bit(31 - j, def_reg);
                 else if ( xend->policy[i][j] == 'k' ||
                           xend->policy[i][j] == 's' )
                     val = test_bit(31 - j, host_reg);
@@ -419,7 +420,7 @@ static int xc_cpuid_xend_policy(
 
  fail:
     free(cur);
-    free(max);
+    free(def);
     free(host);
 
     return rc;