[PATCH v2 4/4] tools/libs: Apply MSR policy to a guest

[Boris Ostrovsky <boris.ostrovsky@oracle.com>]

When creating a guest, if ignore_msrs option has been specified,
apply it to guest's MSR policy.

Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
---
 tools/include/xenctrl.h           |   2 +
 tools/libs/guest/Makefile         |   1 +
 tools/libs/guest/xg_msrs_x86.c    | 110 ++++++++++++++++++++++++++++++++++++++
 tools/libs/light/libxl_dom.c      |   5 +-
 tools/libs/light/libxl_internal.h |   2 +
 tools/libs/light/libxl_x86.c      |   7 +++
 6 files changed, 125 insertions(+), 2 deletions(-)
 create mode 100644 tools/libs/guest/xg_msrs_x86.c

diff --git a/tools/include/xenctrl.h b/tools/include/xenctrl.h
index 3796425e1eca..1d6a38e73dcf 100644
--- a/tools/include/xenctrl.h
+++ b/tools/include/xenctrl.h
@@ -1835,6 +1835,8 @@ int xc_cpuid_apply_policy(xc_interface *xch,
                           const uint32_t *featureset,
                           unsigned int nr_features, bool pae, bool itsc,
                           bool nested_virt, const struct xc_xend_cpuid *xend);
+int xc_msr_apply_policy(xc_interface *xch, uint32_t domid,
+                        unsigned int ignore_msr);
 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/Makefile b/tools/libs/guest/Makefile
index 1c729040b337..452155ea0385 100644
--- a/tools/libs/guest/Makefile
+++ b/tools/libs/guest/Makefile
@@ -56,6 +56,7 @@ SRCS-y                 += xg_dom_compat_linux.c
 
 SRCS-$(CONFIG_X86)     += xg_dom_x86.c
 SRCS-$(CONFIG_X86)     += xg_cpuid_x86.c
+SRCS-$(CONFIG_X86)     += xg_msrs_x86.c
 SRCS-$(CONFIG_ARM)     += xg_dom_arm.c
 
 ifeq ($(CONFIG_LIBXC_MINIOS),y)
diff --git a/tools/libs/guest/xg_msrs_x86.c b/tools/libs/guest/xg_msrs_x86.c
new file mode 100644
index 000000000000..464ce9292ad8
--- /dev/null
+++ b/tools/libs/guest/xg_msrs_x86.c
@@ -0,0 +1,110 @@
+/******************************************************************************
+ * xc_msrs_x86.c
+ *
+ * Update MSR policy of a domain.
+ *
+ * Copyright (c) 2021, Oracle and/or its affiliates.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation;
+ * version 2.1 of the License.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "xc_private.h"
+#include "xen/lib/x86/msr.h"
+
+
+
+int xc_msr_apply_policy(xc_interface *xch, uint32_t domid, unsigned int ignore_msr)
+{
+    int rc;
+    unsigned int nr_leaves, nr_msrs;
+    xen_msr_entry_t *msrs = NULL;
+    struct msr_policy *p = NULL;
+    xc_dominfo_t di;
+    unsigned int err_leaf, err_subleaf, err_msr;
+
+    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_get_cpu_policy_size(xch, &nr_leaves, &nr_msrs);
+    if ( rc )
+    {
+        PERROR("Failed to obtain policy info size");
+        rc = -errno;
+        goto out;
+    }
+
+    rc = -ENOMEM;
+    if ( (msrs = calloc(nr_msrs, sizeof(*msrs))) == NULL ||
+         (p = calloc(1, sizeof(*p))) == NULL )
+        goto out;
+
+    /* Get the domain's default policy. */
+    nr_leaves = 0;
+    rc = xc_get_system_cpu_policy(xch, di.hvm ? XEN_SYSCTL_cpu_policy_hvm_default
+                                              : XEN_SYSCTL_cpu_policy_pv_default,
+                                  &nr_leaves, NULL, &nr_msrs, msrs);
+    if ( rc )
+    {
+        PERROR("Failed to obtain %s default policy", di.hvm ? "hvm" : "pv");
+        rc = -errno;
+        goto out;
+    }
+
+    rc = x86_msr_copy_from_buffer(p, msrs, nr_msrs, &err_msr);
+    if ( rc )
+    {
+        ERROR("Failed to deserialise MSR (err msr %#x) (%d = %s)",
+              err_msr, -rc, strerror(-rc));
+        goto out;
+    }
+
+    p->ignore_msrs = ignore_msr;
+
+    rc = x86_msr_copy_to_buffer(p, msrs, &nr_msrs);
+    if ( rc )
+    {
+        ERROR("Failed to serialise MSR (%d = %s)", -rc, strerror(-rc));
+        goto out;
+    }
+
+    nr_leaves = 0;
+    rc = xc_set_domain_cpu_policy(xch, domid, nr_leaves, NULL, nr_msrs, msrs,
+                                  &err_leaf, &err_subleaf, &err_msr);
+    if ( rc )
+    {
+        PERROR("Failed to set d%d's MSR policy (err leaf %#x, subleaf %#x, msr %#x)",
+               domid, err_leaf, err_subleaf, err_msr);
+        rc = -errno;
+    }
+
+out:
+    free(msrs);
+    free(p);
+
+    return rc;
+}
+
+/*
+ * Local variables:
+ * mode: C
+ * c-basic-offset: 4
+ * indent-tabs-mode: nil
+ * End:
+ */
+
diff --git a/tools/libs/light/libxl_dom.c b/tools/libs/light/libxl_dom.c
index 19168572fd3e..1f2abf6679d7 100644
--- a/tools/libs/light/libxl_dom.c
+++ b/tools/libs/light/libxl_dom.c
@@ -383,9 +383,10 @@ int libxl__build_pre(libxl__gc *gc, uint32_t domid,
     /* Construct a CPUID policy, but only for brand new domains.  Domains
      * being migrated-in/restored have CPUID handled during the
      * static_data_done() callback. */
-    if (!state->restore)
+    if (!state->restore) {
         libxl__cpuid_legacy(ctx, domid, false, info);
-
+        libxl__msr_policy(ctx, domid, info);
+    }
     return rc;
 }
 
diff --git a/tools/libs/light/libxl_internal.h b/tools/libs/light/libxl_internal.h
index c79523ba9248..4f369e6a6f14 100644
--- a/tools/libs/light/libxl_internal.h
+++ b/tools/libs/light/libxl_internal.h
@@ -2054,6 +2054,8 @@ _hidden char *libxl__object_to_json(libxl_ctx *ctx, const char *type,
 
 _hidden void libxl__cpuid_legacy(libxl_ctx *ctx, uint32_t domid, bool retore,
                                  libxl_domain_build_info *info);
+_hidden void libxl__msr_policy(libxl_ctx *ctx, uint32_t domid,
+                               libxl_domain_build_info *info);
 
 /* Calls poll() again - useful to check whether a signaled condition
  * is still true.  Cannot fail.  Returns currently-true revents. */
diff --git a/tools/libs/light/libxl_x86.c b/tools/libs/light/libxl_x86.c
index 86d272999d67..92ec1da77139 100644
--- a/tools/libs/light/libxl_x86.c
+++ b/tools/libs/light/libxl_x86.c
@@ -1,5 +1,6 @@
 #include "libxl_internal.h"
 #include "libxl_arch.h"
+#include "xen/lib/x86/msr.h"
 
 int libxl__arch_domain_prepare_config(libxl__gc *gc,
                                       libxl_domain_config *d_config,
@@ -838,6 +839,12 @@ int libxl__arch_passthrough_mode_setdefault(libxl__gc *gc,
     return rc;
 }
 
+void libxl__msr_policy(libxl_ctx *ctx, uint32_t domid,
+                       libxl_domain_build_info *info)
+{
+    if (info->ignore_msrs != LIBXL_IGNORE_MSRS_NEVER)
+        xc_msr_apply_policy(ctx->xch, domid, info->ignore_msrs);
+}
 
 /*
  * Local variables:
-- 
1.8.3.1