[xen staging] libxg: don't use max policy in xc_cpuid_xend_policy()

[patchbot@xxxxxxx]

commit d0d1003b97279f88232d6ec7a406d3cf58c71327
Author:     Jan Beulich <jbeulich@xxxxxxxx>
AuthorDate: Fri Apr 9 09:14:58 2021 +0200
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Fri Apr 9 09:14:58 2021 +0200

    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@xxxxxxxx>
    Acked-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
---
 tools/libs/guest/xg_cpuid_x86.c | 33 +++++++++++++++++----------------
 1 file changed, 17 insertions(+), 16 deletions(-)

diff --git a/tools/libs/guest/xg_cpuid_x86.c b/tools/libs/guest/xg_cpuid_x86.c
index aae6931a11..5ea69ad3d5 100644
--- 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;
--
generated by git-patchbot for /home/xen/git/xen.git#staging