[PATCH 20/21] libs/{light,guest}: implement xc_cpuid_apply_policy in libxl

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

With the addition of the xc_cpu_policy_* now libxl can have better
control over the cpu policy, this allows removing the
xc_cpuid_apply_policy function and instead coding the required bits by
libxl in libxl__cpuid_legacy directly.

Remove xc_cpuid_apply_policy.

Signed-off-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
---
I'm unsure why this is called libxl__cpuid_legacy, mostly because I
don't seem to be able to spot a libxl__cpuid (ie: non-legacy version).
Should this be renamed to libxl__cpuid?

1b3cec69bf300e012a mentions the process of switching to a new cpuid
interface, but I'm not sure we need to keep libxl__cpuid_legacy, since
that's an internal interface that's not exposed to libxl clients
anyway.
---
 tools/include/xenctrl.h         |  18 -----
 tools/libs/guest/xg_cpuid_x86.c | 123 --------------------------------
 tools/libs/light/libxl_cpuid.c  |  87 ++++++++++++++++++++--
 3 files changed, 83 insertions(+), 145 deletions(-)

diff --git a/tools/include/xenctrl.h b/tools/include/xenctrl.h
index a830fac1d12..5a576f72b4d 100644
--- a/tools/include/xenctrl.h
+++ b/tools/include/xenctrl.h
@@ -1890,24 +1890,6 @@ struct xc_xend_cpuid {
     char *policy[4];
 };
 
-/*
- * Make adjustments to the CPUID settings for a domain.
- *
- * This path is used in two cases.  First, for fresh boots of the domain, and
- * secondly for migrate-in/restore of pre-4.14 guests (where CPUID data was
- * missing from the stream).  The @restore parameter distinguishes these
- * cases, and the generated policy must be compatible with a 4.13.
- *
- * Either pass a full new @featureset (and @nr_features), or adjust individual
- * features (@pae, @itsc, @nested_virt).
- *
- * Then (optionally) apply legacy XEND overrides (@xend) to the result.
- */
-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);
 int xc_mca_op(xc_interface *xch, struct xen_mc *mc);
 int xc_mca_op_inject_v2(xc_interface *xch, unsigned int flags,
                         xc_cpumap_t cpumap, unsigned int nr_cpus);
diff --git a/tools/libs/guest/xg_cpuid_x86.c b/tools/libs/guest/xg_cpuid_x86.c
index 96b969342fa..dffb9923b33 100644
--- a/tools/libs/guest/xg_cpuid_x86.c
+++ b/tools/libs/guest/xg_cpuid_x86.c
@@ -383,129 +383,6 @@ int xc_cpu_policy_apply_cpuid(xc_interface *xch, 
xc_cpu_policy_t policy,
     return rc;
 }
 
-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 *cpuid)
-{
-    int rc;
-    xc_dominfo_t di;
-    unsigned int nr_leaves, nr_msrs;
-    xen_cpuid_leaf_t *leaves = NULL;
-    struct cpuid_policy *p = NULL;
-    struct cpu_policy policy = { };
-    uint32_t err_leaf = -1, err_subleaf = -1, err_msr = -1;
-
-    if ( xc_domain_getinfo(xch, domid, 1, &di) != 1 ||
-         di.domid != domid )
-    {
-        ERROR("Failed to obtain d%d info", domid);
-        rc = -ESRCH;
-        goto out;
-    }
-
-    rc = xc_cpu_policy_get_size(xch, &nr_leaves, &nr_msrs);
-    if ( rc )
-    {
-        PERROR("Failed to obtain policy info size");
-        rc = -errno;
-        goto out;
-    }
-
-    rc = -ENOMEM;
-    if ( (leaves = calloc(nr_leaves, sizeof(*leaves))) == NULL ||
-         (p = calloc(1, sizeof(*p))) == NULL )
-        goto out;
-
-    /* Get the domain's default policy. */
-    nr_msrs = 0;
-    rc = get_system_cpu_policy(xch, di.hvm ? XEN_SYSCTL_cpu_policy_hvm_default
-                                           : XEN_SYSCTL_cpu_policy_pv_default,
-                               &nr_leaves, leaves, &nr_msrs, NULL);
-    if ( rc )
-    {
-        PERROR("Failed to obtain %s default policy", di.hvm ? "hvm" : "pv");
-        rc = -errno;
-        goto out;
-    }
-
-    rc = x86_cpuid_copy_from_buffer(p, leaves, nr_leaves,
-                                    &err_leaf, &err_subleaf);
-    if ( rc )
-    {
-        ERROR("Failed to deserialise CPUID (err leaf %#x, subleaf %#x) (%d = 
%s)",
-              err_leaf, err_subleaf, -rc, strerror(-rc));
-        goto out;
-    }
-
-    /*
-     * Account for feature which have been disabled by default since Xen 4.13,
-     * so migrated-in VM's don't risk seeing features disappearing.
-     */
-    if ( restore )
-    {
-        policy.cpuid = p;
-        xc_cpu_policy_make_compatible(xch, &policy, di.hvm);
-    }
-
-    if ( featureset )
-    {
-        policy.cpuid = p;
-        rc = xc_cpu_policy_apply_featureset(xch, &policy, featureset,
-                                            nr_features);
-        if ( rc )
-        {
-            ERROR("Failed to apply featureset to policy");
-            goto out;
-        }
-    }
-    else
-    {
-        p->extd.itsc = itsc;
-
-        if ( di.hvm )
-        {
-            p->basic.pae = pae;
-            p->basic.vmx = nested_virt;
-            p->extd.svm = nested_virt;
-        }
-    }
-
-    policy.cpuid = p;
-    rc = xc_cpu_policy_topology(xch, &policy, di.hvm);
-    if ( rc )
-        goto out;
-
-    rc = xc_cpu_policy_apply_cpuid(xch, &policy, cpuid, di.hvm);
-    if ( rc )
-        goto out;
-
-    rc = x86_cpuid_copy_to_buffer(p, leaves, &nr_leaves);
-    if ( rc )
-    {
-        ERROR("Failed to serialise CPUID (%d = %s)", -rc, strerror(-rc));
-        goto out;
-    }
-
-    rc = set_domain_cpu_policy(xch, domid, nr_leaves, leaves, 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 out;
-    }
-
-    rc = 0;
-
-out:
-    free(p);
-    free(leaves);
-
-    return rc;
-}
-
 xc_cpu_policy_t xc_cpu_policy_init(void)
 {
     xc_cpu_policy_t policy = calloc(1, sizeof(*policy));
diff --git a/tools/libs/light/libxl_cpuid.c b/tools/libs/light/libxl_cpuid.c
index a7b33bbcd06..f1418382b62 100644
--- a/tools/libs/light/libxl_cpuid.c
+++ b/tools/libs/light/libxl_cpuid.c
@@ -423,6 +423,8 @@ int libxl__cpuid_legacy(libxl_ctx *ctx, uint32_t domid, 
bool restore,
                         libxl_domain_build_info *info)
 {
     GC_INIT(ctx);
+    xc_cpu_policy_t policy = NULL;
+    bool hvm = info->type == LIBXL_DOMAIN_TYPE_HVM;
     bool pae = true;
     bool itsc;
     int rc;
@@ -436,6 +438,42 @@ int libxl__cpuid_legacy(libxl_ctx *ctx, uint32_t domid, 
bool restore,
      */
     bool nested_virt = info->nested_hvm.val > 0;
 
+    policy = xc_cpu_policy_init();
+    if (!policy) {
+        LOGE(ERROR, "Failed to init CPU policy");
+        rc = ERROR_FAIL;
+        goto out;
+    }
+
+    rc = xc_cpu_policy_get_domain(ctx->xch, domid, policy);
+    if (rc) {
+        LOGE(ERROR, "Failed to fetch domain %u CPU policy", domid);
+        rc = ERROR_FAIL;
+        goto out;
+    }
+
+    /*
+     * Account for feature which have been disabled by default since Xen 4.13,
+     * so migrated-in VM's don't risk seeing features disappearing.
+     */
+    if (restore) {
+        rc = xc_cpu_policy_make_compatible(ctx->xch, policy, hvm);
+        if (rc) {
+            LOGE(ERROR, "Failed to setup compatible CPU policy for domain  %u",
+                 domid);
+            rc = ERROR_FAIL;
+            goto out;
+        }
+    }
+
+    rc = xc_cpu_policy_topology(ctx->xch, policy, hvm);
+    if (rc) {
+        LOGE(ERROR, "Failed to setup CPU policy topology for domain  %u",
+             domid);
+        rc = ERROR_FAIL;
+        goto out;
+    }
+
     /*
      * For PV guests, PAE is Xen-controlled (it is the 'p' that differentiates
      * the xen-3.0-x86_32 and xen-3.0-x86_32p ABIs).  It is mandatory as Xen
@@ -446,8 +484,15 @@ int libxl__cpuid_legacy(libxl_ctx *ctx, uint32_t domid, 
bool restore,
      *
      * HVM guests get a top-level choice of whether PAE is available.
      */
-    if (info->type == LIBXL_DOMAIN_TYPE_HVM)
+    if (hvm)
         pae = libxl_defbool_val(info->u.hvm.pae);
+    rc = libxl_cpuid_parse_config(&info->cpuid, GCSPRINTF("pae=%d", pae));
+    if (rc) {
+        LOG(ERROR, "Unable to set PAE CPUID flag: %d", rc);
+        rc = ERROR_FAIL;
+        goto out;
+    }
+
 
     /*
      * Advertising Invariant TSC to a guest means that the TSC frequency won't
@@ -463,12 +508,46 @@ int libxl__cpuid_legacy(libxl_ctx *ctx, uint32_t domid, 
bool restore,
      */
     itsc = (libxl_defbool_val(info->disable_migrate) ||
             info->tsc_mode == LIBXL_TSC_MODE_ALWAYS_EMULATE);
+    rc = libxl_cpuid_parse_config(&info->cpuid, GCSPRINTF("invtsc=%d", itsc));
+    if (rc) {
+        LOG(ERROR, "Unable to set Invariant TSC CPUID flag: %d", rc);
+        rc = ERROR_FAIL;
+        goto out;
+    }
+
+    /* Set Nested virt CPUID bits for HVM. */
+    if (hvm) {
+        rc = libxl_cpuid_parse_config(&info->cpuid, GCSPRINTF("vmx=%d",
+                                                              nested_virt));
+        if (rc) {
+            LOG(ERROR, "Unable to set VMX CPUID flag: %d", rc);
+            rc = ERROR_FAIL;
+            goto out;
+        }
+
+        rc = libxl_cpuid_parse_config(&info->cpuid, GCSPRINTF("svm=%d",
+                                                              nested_virt));
+        if (rc) {
+            LOG(ERROR, "Unable to set SVM CPUID flag: %d", rc);
+            rc = ERROR_FAIL;
+            goto out;
+        }
+    }
+
+    /* Apply the bits from info->cpuid if any. */
+    rc = xc_cpu_policy_apply_cpuid(ctx->xch, policy, info->cpuid, hvm);
+    if (rc) {
+        LOGE(ERROR, "Failed to apply CPUID changes");
+        rc = ERROR_FAIL;
+        goto out;
+    }
 
-    rc = xc_cpuid_apply_policy(ctx->xch, domid, restore, NULL, 0,
-                               pae, itsc, nested_virt, info->cpuid);
+    rc = xc_cpu_policy_set_domain(ctx->xch, domid, policy);
     if (rc)
-        LOGE(ERROR, "Failed to apply CPUID policy");
+        LOGE(ERROR, "Failed to set domain %u CPUID policy", domid);
 
+ out:
+    xc_cpu_policy_destroy(policy);
     GC_FREE;
     return rc;
 }
-- 
2.30.1