[PATCH v7 07/11] libs/guest: rework xc_cpuid_xend_policy

[Roger Pau Monne <roger.pau@xxxxxxxxxx>]

Rename xc_cpuid_xend_policy to xc_cpu_policy_apply_cpuid and make it
public. Modify the function internally to use the new xc_cpu_policy_*
set of functions. Also don't apply the passed policy to a domain
directly, and instead modify the provided xc_cpu_policy_t. The caller
will be responsible of applying the modified cpu policy to the domain.

Note that further patches will end up removing this function, as the
callers should have the necessary helpers to modify an xc_cpu_policy_t
themselves.

The find_leaf helper and related comparison function is also removed,
as it's no longer needed to search for cpuid leafs as finding the
matching leaves is now done using xc_cpu_policy_get_cpuid.

No functional change intended.

Signed-off-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
---
Changes since v6:
 - Pass a host policy to xc_cpuid_apply_policy.

Changes since v3:
 - Drop find_leaf and comparison helper.
---
 tools/include/xenguest.h        |   5 +
 tools/libs/guest/xg_cpuid_x86.c | 203 ++++++++++++--------------------
 2 files changed, 81 insertions(+), 127 deletions(-)

diff --git a/tools/include/xenguest.h b/tools/include/xenguest.h
index 5e60f81192..98a998f11d 100644
--- a/tools/include/xenguest.h
+++ b/tools/include/xenguest.h
@@ -830,6 +830,11 @@ void xc_cpu_policy_make_compat_4_12(xc_interface *xch, 
xc_cpu_policy_t *policy,
 void xc_cpu_policy_legacy_topology(xc_interface *xch, xc_cpu_policy_t *policy,
                                    const xc_cpu_policy_t *host);
 
+/* Apply an xc_xend_cpuid object to the policy. */
+int xc_cpu_policy_apply_cpuid(xc_interface *xch, xc_cpu_policy_t *policy,
+                              const xc_cpu_policy_t *host,
+                              const struct xc_xend_cpuid *cpuid, bool hvm);
+
 int xc_get_cpu_levelling_caps(xc_interface *xch, uint32_t *caps);
 int xc_get_cpu_featureset(xc_interface *xch, uint32_t index,
                           uint32_t *nr_features, uint32_t *featureset);
diff --git a/tools/libs/guest/xg_cpuid_x86.c b/tools/libs/guest/xg_cpuid_x86.c
index 6d8d16eed5..3503f21793 100644
--- a/tools/libs/guest/xg_cpuid_x86.c
+++ b/tools/libs/guest/xg_cpuid_x86.c
@@ -254,144 +254,99 @@ int xc_set_domain_cpu_policy(xc_interface *xch, uint32_t 
domid,
     return ret;
 }
 
-static int compare_leaves(const void *l, const void *r)
-{
-    const xen_cpuid_leaf_t *lhs = l;
-    const xen_cpuid_leaf_t *rhs = r;
-
-    if ( lhs->leaf != rhs->leaf )
-        return lhs->leaf < rhs->leaf ? -1 : 1;
-
-    if ( lhs->subleaf != rhs->subleaf )
-        return lhs->subleaf < rhs->subleaf ? -1 : 1;
-
-    return 0;
-}
-
-static xen_cpuid_leaf_t *find_leaf(
-    xen_cpuid_leaf_t *leaves, unsigned int nr_leaves,
-    const struct xc_xend_cpuid *xend)
-{
-    const xen_cpuid_leaf_t key = { xend->leaf, xend->subleaf };
-
-    return bsearch(&key, leaves, nr_leaves, sizeof(*leaves), compare_leaves);
-}
-
-static int xc_cpuid_xend_policy(
-    xc_interface *xch, uint32_t domid, const struct xc_xend_cpuid *xend)
+int xc_cpu_policy_apply_cpuid(xc_interface *xch, xc_cpu_policy_t *policy,
+                              const xc_cpu_policy_t *host,
+                              const struct xc_xend_cpuid *cpuid, bool hvm)
 {
     int rc;
-    xc_dominfo_t di;
-    unsigned int nr_leaves, nr_msrs;
-    uint32_t err_leaf = -1, err_subleaf = -1, err_msr = -1;
-    /*
-     * Three full policies.  The host, default for the domain type,
-     * and domain current.
-     */
-    xen_cpuid_leaf_t *host = NULL, *def = NULL, *cur = NULL;
-    unsigned int nr_host, nr_def, nr_cur;
+    xc_cpu_policy_t *def = NULL;
 
-    if ( xc_domain_getinfo(xch, domid, 1, &di) != 1 ||
-         di.domid != domid )
+    def = xc_cpu_policy_init();
+    if ( !def )
     {
-        ERROR("Failed to obtain d%d info", domid);
-        rc = -ESRCH;
-        goto fail;
-    }
-
-    rc = xc_cpu_policy_get_size(xch, &nr_leaves, &nr_msrs);
-    if ( rc )
-    {
-        PERROR("Failed to obtain policy info size");
-        rc = -errno;
-        goto fail;
-    }
-
-    rc = -ENOMEM;
-    if ( (host = calloc(nr_leaves, sizeof(*host))) == 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);
-        goto fail;
-    }
-
-    /* Get the domain's current policy. */
-    nr_msrs = 0;
-    nr_cur = nr_leaves;
-    rc = get_domain_cpu_policy(xch, domid, &nr_cur, cur, &nr_msrs, NULL);
-    if ( rc )
-    {
-        PERROR("Failed to obtain d%d current policy", domid);
-        rc = -errno;
-        goto fail;
+        PERROR("Failed to init policy");
+        rc = -ENOMEM;
+        goto out;
     }
 
     /* Get the domain type's default policy. */
-    nr_msrs = 0;
-    nr_def = nr_leaves;
-    rc = get_system_cpu_policy(xch, di.hvm ? XEN_SYSCTL_cpu_policy_hvm_default
+    rc = xc_cpu_policy_get_system(xch, 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 def policy", di.hvm ? "hvm" : "pv");
-        rc = -errno;
-        goto fail;
-    }
-
-    /* Get the host policy. */
-    nr_msrs = 0;
-    nr_host = nr_leaves;
-    rc = get_system_cpu_policy(xch, XEN_SYSCTL_cpu_policy_host,
-                               &nr_host, host, &nr_msrs, NULL);
+                                  def);
     if ( rc )
     {
-        PERROR("Failed to obtain host policy");
-        rc = -errno;
-        goto fail;
+        PERROR("Failed to obtain %s def policy", hvm ? "hvm" : "pv");
+        goto out;
     }
 
     rc = -EINVAL;
-    for ( ; xend->leaf != XEN_CPUID_INPUT_UNUSED; ++xend )
+    for ( ; cpuid->leaf != XEN_CPUID_INPUT_UNUSED; ++cpuid )
     {
-        xen_cpuid_leaf_t *cur_leaf = find_leaf(cur, nr_cur, 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);
+        xen_cpuid_leaf_t cur_leaf;
+        xen_cpuid_leaf_t def_leaf;
+        xen_cpuid_leaf_t host_leaf;
 
-        if ( cur_leaf == NULL || def_leaf == NULL || host_leaf == NULL )
+        rc = xc_cpu_policy_get_cpuid(xch, policy, cpuid->leaf, cpuid->subleaf,
+                                     &cur_leaf);
+        if ( rc )
         {
-            ERROR("Missing leaf %#x, subleaf %#x", xend->leaf, xend->subleaf);
-            goto fail;
+            ERROR("Failed to get current policy leaf %#x subleaf %#x",
+                  cpuid->leaf, cpuid->subleaf);
+            goto out;
+        }
+        rc = xc_cpu_policy_get_cpuid(xch, def, cpuid->leaf, cpuid->subleaf,
+                                     &def_leaf);
+        if ( rc )
+        {
+            ERROR("Failed to get def policy leaf %#x subleaf %#x",
+                  cpuid->leaf, cpuid->subleaf);
+            goto out;
+        }
+        rc = xc_cpu_policy_get_cpuid(xch, host, cpuid->leaf, cpuid->subleaf,
+                                     &host_leaf);
+        if ( rc )
+        {
+            ERROR("Failed to get host policy leaf %#x subleaf %#x",
+                  cpuid->leaf, cpuid->subleaf);
+            goto out;
         }
 
-        for ( unsigned int i = 0; i < ARRAY_SIZE(xend->policy); i++ )
+        for ( unsigned int i = 0; i < ARRAY_SIZE(cpuid->policy); i++ )
         {
-            uint32_t *cur_reg = &cur_leaf->a + i;
-            const uint32_t *def_reg = &def_leaf->a + i;
-            const uint32_t *host_reg = &host_leaf->a + i;
+            uint32_t *cur_reg = &cur_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 )
+            if ( cpuid->policy[i] == NULL )
                 continue;
 
             for ( unsigned int j = 0; j < 32; j++ )
             {
                 bool val;
 
-                if ( xend->policy[i][j] == '1' )
+                switch ( cpuid->policy[i][j] )
+                {
+                case '1':
                     val = true;
-                else if ( xend->policy[i][j] == '0' )
+                    break;
+
+                case '0':
                     val = false;
-                else if ( xend->policy[i][j] == 'x' )
+                    break;
+
+                case 'x':
                     val = test_bit(31 - j, def_reg);
-                else if ( xend->policy[i][j] == 'k' ||
-                          xend->policy[i][j] == 's' )
+                    break;
+
+                case 'k':
+                case 's':
                     val = test_bit(31 - j, host_reg);
-                else
-                {
+                    break;
+
+                default:
                     ERROR("Bad character '%c' in policy[%d] string '%s'",
-                          xend->policy[i][j], i, xend->policy[i]);
-                    goto fail;
+                          cpuid->policy[i][j], i, cpuid->policy[i]);
+                    goto out;
                 }
 
                 clear_bit(31 - j, cur_reg);
@@ -399,25 +354,18 @@ static int xc_cpuid_xend_policy(
                     set_bit(31 - j, cur_reg);
             }
         }
-    }
 
-    /* Feed the transformed currrent policy back up to Xen. */
-    rc = xc_set_domain_cpu_policy(xch, domid, nr_cur, cur, 0, NULL,
-                                  &err_leaf, &err_subleaf, &err_msr);
-    if ( rc )
-    {
-        PERROR("Failed to set d%d's policy (err leaf %#x, subleaf %#x, msr 
%#x)",
-               domid, err_leaf, err_subleaf, err_msr);
-        rc = -errno;
-        goto fail;
+        rc = xc_cpu_policy_update_cpuid(xch, policy, &cur_leaf, 1);
+        if ( rc )
+        {
+            PERROR("Failed to set policy leaf %#x subleaf %#x",
+                   cpuid->leaf, cpuid->subleaf);
+            goto out;
+        }
     }
 
-    /* Success! */
-
- fail:
-    free(cur);
-    free(def);
-    free(host);
+ out:
+    xc_cpu_policy_destroy(def);
 
     return rc;
 }
@@ -425,7 +373,7 @@ static int xc_cpuid_xend_policy(
 int xc_cpuid_apply_policy(xc_interface *xch, uint32_t domid, bool restore,
                           const uint32_t *featureset, unsigned int nr_features,
                           bool pae, bool itsc, bool nested_virt,
-                          const struct xc_xend_cpuid *xend)
+                          const struct xc_xend_cpuid *cpuid)
 {
     int rc;
     xc_dominfo_t di;
@@ -554,6 +502,10 @@ int xc_cpuid_apply_policy(xc_interface *xch, uint32_t 
domid, bool restore,
     xc_cpu_policy_legacy_topology(xch, policy, di.hvm ? NULL : host);
     *p = policy->cpuid;
 
+    rc = xc_cpu_policy_apply_cpuid(xch, policy, host, cpuid, di.hvm);
+    if ( rc )
+        goto out;
+
     rc = x86_cpuid_copy_to_buffer(p, leaves, &nr_leaves);
     if ( rc )
     {
@@ -571,9 +523,6 @@ int xc_cpuid_apply_policy(xc_interface *xch, uint32_t 
domid, bool restore,
         goto out;
     }
 
-    if ( xend && (rc = xc_cpuid_xend_policy(xch, domid, xend)) )
-        goto out;
-
     rc = 0;
 
 out:
-- 
2.34.1