[PATCH v7 0/2] x86/viridian improvements

[PATCH v7 0/2] x86/viridian improvements

[Paul Durrant]

This patch series incorporates several improvements to the code
supporting viridian (i.e. hyper-v compatible) enlightenments for
Windows guests:

Patch #1 series lays the foundations for adding new viridian
enlightenments such that they can be optionally enabled, and not
immediately exposed to a guest across a save/restore boundary.

Patch #2 adds support for the 'Partition Time Reference Counter'
enlightenment.

v2:
- Addressed comments from Jan Beulich
- Added patch #2

v3:
- Addressed comments from Andrew Cooper and Jan Beulich
- Re-worked patch #2
- Simplified patch #3 to use guest TSC

v4:
- Added missing domain info to printks in patch #2

v5:
- Clarified comment of patch #1 as suggested by David Vrabel
- More logging tweaks in patch #2 as suggested by Andrew Cooper

v6:
- Dropped previous patch to reduce logging verbosity as it has been
  applied
- Toolstack changes only:
  - New libxl_integer_list and libxl_viridian_enlightenment types to
    avoid passing of strings between xl and libxl, as requested by
    Ian Jackson.
  - Retained and deprecated viridian defbool rather than replacing it
    to avoid API breakage pointed out by Ian Campbell. Enlightenment list
    is now in a new hvm-only viridian_enlightenments field of the build
    info.

v7:
- Changes to patch #2 only:
  - Reference time calculation now makes use of struct time_scale and
    set_time_scale and scale_delta functions to avoid overflow issues
    pointed out by Christoph Egger.

[PATCH v7 1/2] x86/viridian: Re-purpose the HVM parameter to be a feature mask

[Paul Durrant]

The following commits introduced the time reference counter MSR and
TSC/APIC frequency MSRs into the viridian feature set respectively:

e36cd2cdc9674a7a4855d21fb7b3e6e17c4bb33b
84657efd9116f40924aa13c9d5a349e007da716f

The time reference counter MSR feature was then reverted by commit

1cd4fab14ce25859efa4a2af13475e6650a5506c

because a flaw in the implementation meant the counter was reset on
migration.

All of these changes were made without any addtional options being
added to the VM configuration, or any compatibility checks being made
in the domain save/restore code. Hence setting the single boolean
'viridian' option in the VM configuration yields a different set of
features depending on which version of Xen the VM is started on, and the
feature set can change across migration (so new MSRs can magically appear).

This patch grandfathers in the current viridian features set and calls them
the 'base' and 'freq' feature sets. HVM_PARAM_VIRIDIAN is re-purposed as
a feature mask. The hypervisor has only ever allowed it ot be set to 0
or 1, so the presence of the base and freq sets are indicated by setting
bit 0. The freq set can then be turned off by setting bit 1, thus
restoring the pre-Xen-4.4 base set. Newly implemented viridian features
can be optionally enabled in future by setting further bits.

The viridian option in xl.cfg(5) has also been changed to a string list so
that the sets can be individually sepcified. For compatibility, if the
option is specified as a boolean, then a true (1) value will be translated
to a string list containing "base" and "freq".

This patch also alters the allowed write accesses to HVM_PARAM_VIRIDIAN.
Currently there is nothing to stop the guest writing this value (which,
while harmless to anything else, should not happen) and nothing to
stop a toolstack from setting the value back to zero whilst the guest is
running, causing CPUID leaves to disappear and MSR accesses to start
causing GPFs in the guest. Both of these possibilities are now disallowed:
Once the parameter is set to a non-zero value it may not be cleared, and
guests no longer have any write access.

Signed-off-by: Paul Durrant <paul.durrant@citrix.com>
Cc: Keir Fraser <keir@xen.org>
Acked-by: Jan Beulich <jbeulich@suse.com>
Cc: Ian Campbell <ian.campbell@citrix.com>
Cc: Ian Jackson <ian.jackson@eu.citrix.com>
Cc: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Cc: David Scott <dave.scott@eu.citrix.com>
---
 docs/man/xl.cfg.pod.5                |   53 +++++++++++++++++++------
 tools/libxc/xc_domain_restore.c      |    4 +-
 tools/libxl/gentest.py               |   16 +++++++-
 tools/libxl/libxl.c                  |   59 ++++++++++++++++++++++++++++
 tools/libxl/libxl.h                  |   22 +++++++++++
 tools/libxl/libxl_dom.c              |   71 +++++++++++++++++++++++++++++-----
 tools/libxl/libxl_internal.h         |    7 ++++
 tools/libxl/libxl_json.c             |   50 ++++++++++++++++++++++++
 tools/libxl/libxl_json.h             |    1 +
 tools/libxl/libxl_types.idl          |   13 +++++++
 tools/libxl/xl_cmdimpl.c             |   51 ++++++++++++++++++++++--
 tools/ocaml/libs/xl/genwrap.py       |    1 +
 tools/ocaml/libs/xl/xenlight_stubs.c |   33 ++++++++++++++++
 tools/python/xen/lowlevel/xl/xl.c    |    6 +++
 xen/arch/x86/hvm/hvm.c               |   18 ++++++++-
 xen/arch/x86/hvm/viridian.c          |   21 +++++++++-
 xen/include/asm-x86/hvm/hvm.h        |    7 +++-
 xen/include/public/hvm/params.h      |   33 +++++++++++++++-
 18 files changed, 433 insertions(+), 33 deletions(-)

diff --git a/docs/man/xl.cfg.pod.5 b/docs/man/xl.cfg.pod.5
index 1e04eed..d91f101 100644
--- a/docs/man/xl.cfg.pod.5
+++ b/docs/man/xl.cfg.pod.5
@@ -1106,18 +1106,47 @@ Windows L<http://wiki.xen.org/wiki/XenWindowsGplPv>.
 Setting B<xen_platform_pci=0> with the default device_model "qemu-xen"
 requires at least QEMU 1.6.
 
-=item B<viridian=BOOLEAN>
-
-Turns on or off the exposure of MicroSoft Hyper-V (AKA viridian)
-compatible enlightenments to the guest.  These can improve performance
-of Microsoft Windows guests from Windows Vista and Windows 2008
-onwards and setting this option for such guests is strongly
-recommended. This option should be harmless for other versions of
-Windows (although it will not give any benefit) and the majority of
-other non-Windows OSes. However it is known to be incompatible with
-some other Operating Systems and in some circumstance can prevent
-Xen's own paravirtualisation interfaces for HVM guests from being
-used.
+=item B<viridian=[ "SET", "SET", ...]>
+
+The sets of Microsoft Hyper-V (AKA viridian) compatible enlightenments
+exposed to the guest. The following sets of enlightenments may be
+specified:
+
+=over 4
+
+=item B<base>
+
+This set incorporates the Hypercall MSRs, Virtual processor index MSR,
+and APIC access MSRs. This set is a pre-requisite for all other sets.
+If it is not specified then all enlightenments will be disabled.
+
+These enlightenments can improve performance of Windows Vista and Windows
+Server 2008 onwards and setting this option for such guests is strongly
+recommended.
+
+=item B<freq>
+
+This set incorporates the TSC and APIC frequency MSRs.
+
+This enlightenment can improve performance of Windows 7 and Windows
+Server 2008 R2 onwards.
+
+=back
+ 
+See the latest version of Microsoft's Hypervisor Top-Level Functional
+Specification for more details.
+
+The enlightenments should be harmless for other versions of Windows
+(although they will not give any benefit) and the majority of other
+non-Windows OSes.
+However it is known that they are incompatible with some other Operating
+Systems and in some circumstance can prevent Xen's own paravirtualisation
+interfaces for HVM guests from being used.
+
+Specifying the viridian option as a boolean is deprecated. However, for
+backwards compatibility, if it is specified as a boolean a value of
+true (1) will cause both the 'base' and 'freq' sets to be exposed to
+the guest, and a value of false (0) will disable all enlightenments.
 
 =back
 
diff --git a/tools/libxc/xc_domain_restore.c b/tools/libxc/xc_domain_restore.c
index b9a56d5..d362e3a 100644
--- a/tools/libxc/xc_domain_restore.c
+++ b/tools/libxc/xc_domain_restore.c
@@ -922,7 +922,7 @@ static int pagebuf_get_one(xc_interface *xch, struct restore_ctx *ctx,
         if ( RDEXACT(fd, &buf->viridian, sizeof(uint32_t)) ||
              RDEXACT(fd, &buf->viridian, sizeof(uint64_t)) )
         {
-            PERROR("error read the viridian flag");
+            PERROR("error reading the viridian enlightenments");
             return -1;
         }
         return pagebuf_get_one(xch, ctx, buf, fd, dom);
@@ -1733,7 +1733,7 @@ int xc_domain_restore(xc_interface *xch, int io_fd, uint32_t dom,
     }
 
     if (pagebuf.viridian != 0)
-        xc_hvm_param_set(xch, dom, HVM_PARAM_VIRIDIAN, 1);
+        xc_hvm_param_set(xch, dom, HVM_PARAM_VIRIDIAN, pagebuf.viridian);
 
     /*
      * If we are migrating in from a host that does not support
diff --git a/tools/libxl/gentest.py b/tools/libxl/gentest.py
index 95323d1..2562ddf 100644
--- a/tools/libxl/gentest.py
+++ b/tools/libxl/gentest.py
@@ -21,7 +21,8 @@ def randomize_enum(e):
     return random.choice([v.name for v in e.values])
 
 handcoded = ["libxl_bitmap", "libxl_key_value_list",
-             "libxl_cpuid_policy_list", "libxl_string_list"]
+             "libxl_cpuid_policy_list", "libxl_string_list",
+             "libxl_integer_list"]
 
 def gen_rand_init(ty, v, indent = "    ", parent = None):
     s = ""
@@ -192,6 +193,19 @@ static void libxl_cpuid_policy_list_rand_init(libxl_cpuid_policy_list *pp)
     *pp = p;
 }
 
+static void libxl_integer_list_rand_init(libxl_integer_list *pil)
+{
+    int i, nr = rand() % 16;
+    libxl_integer_list il;
+
+    il.count = nr;
+    il.array = calloc(nr, sizeof(int));
+    for (i = 0; i < nr; i++)
+        il.array[i] = rand();
+
+    *pil = il;
+}
+
 static void libxl_string_list_rand_init(libxl_string_list *p)
 {
     int i, nr = rand() % 16;
diff --git a/tools/libxl/libxl.c b/tools/libxl/libxl.c
index 3526539..20fbbbd 100644
--- a/tools/libxl/libxl.c
+++ b/tools/libxl/libxl.c
@@ -192,6 +192,65 @@ int libxl_ctx_free(libxl_ctx *ctx)
     return 0;
 }
 
+void libxl_integer_list_init(libxl_integer_list *pil)
+{
+    pil->count = 0;
+}
+
+void libxl_integer_list_dispose(libxl_integer_list *pil)
+{
+    if (pil->count != 0)
+        free(pil->array);
+}
+
+void libxl_integer_list_append(libxl_ctx *ctx,
+                               libxl_integer_list *pil,
+                               int v)
+{
+    GC_INIT(ctx);
+    int i;
+
+    i = pil->count++;
+    pil->array = libxl__realloc(NOGC,
+                                pil->array,
+                                pil->count * sizeof(int));
+    pil->array[i] = v;
+
+    GC_FREE;
+}
+
+int libxl_integer_list_item(libxl_integer_list *pil, unsigned int i)
+{
+    assert(i < pil->count);
+
+    return pil->array[i];
+}
+
+void libxl_integer_list_copy(libxl_ctx *ctx,
+                             libxl_integer_list *dst,
+                             libxl_integer_list *src)
+{
+    GC_INIT(ctx);
+    int i;
+
+    dst->count = src->count;
+    if (dst->count == 0)
+        goto out;
+
+    dst->array = libxl__calloc(NOGC, dst->count, sizeof(int));
+
+    for (i = 0; i < dst->count; i++)
+        dst->array[i] = src->array[i];
+
+out:
+    GC_FREE;
+}
+
+int libxl_integer_list_length(const libxl_integer_list *pil)
+{
+    return pil->count;
+}
+
 void libxl_string_list_dispose(libxl_string_list *psl)
 {
     int i;
diff --git a/tools/libxl/libxl.h b/tools/libxl/libxl.h
index bfeb3bc..3bebb5e 100644
--- a/tools/libxl/libxl.h
+++ b/tools/libxl/libxl.h
@@ -128,6 +128,15 @@
 #define LIBXL_HAVE_LIBXL_DEVICE_DISK_DISCARD_ENABLE 1
 
 /*
+ * LIBXL_HAVE_BUILDINFO_HVM_VIRIDIAN_ENLIGHTENMENTS indicates that
+ * the viridian_enlightenments field is present in the hvm sections of
+ * libxl_domain_build_info. This field tells libxl which specific
+ * viridian (Hyper-V) enlightenments to enable, replacing the single
+ * viridian defbool which is only retained for API compatibility.
+ */
+#define LIBXL_HAVE_BUILDINFO_HVM_VIRIDIAN_ENLIGHTENMENTS 1
+
+/*
  * libxl ABI compatibility
  *
  * The only guarantee which libxl makes regarding ABI compatibility
@@ -584,6 +593,19 @@ typedef uint8_t libxl_mac[6];
 #define LIBXL_MAC_BYTES(mac) mac[0], mac[1], mac[2], mac[3], mac[4], mac[5]
 void libxl_mac_copy(libxl_ctx *ctx, libxl_mac *dst, libxl_mac *src);
 
+typedef struct {
+    unsigned int count;
+    int *array;
+} libxl_integer_list;
+void libxl_integer_list_init(libxl_integer_list *il);
+void libxl_integer_list_append(libxl_ctx *ctx, libxl_integer_list *il,
+                               int v);
+int libxl_integer_list_item(libxl_integer_list *il, unsigned int i);
+void libxl_integer_list_dispose(libxl_integer_list *il);
+int libxl_integer_list_length(const libxl_integer_list *il);
+void libxl_integer_list_copy(libxl_ctx *ctx, libxl_integer_list *dst,
+                             libxl_integer_list *src);
+
 typedef char **libxl_string_list;
 void libxl_string_list_dispose(libxl_string_list *sl);
 int libxl_string_list_length(const libxl_string_list *sl);
diff --git a/tools/libxl/libxl_dom.c b/tools/libxl/libxl_dom.c
index c944804..e854984 100644
--- a/tools/libxl/libxl_dom.c
+++ b/tools/libxl/libxl_dom.c
@@ -209,21 +209,74 @@ static unsigned long timer_mode(const libxl_domain_build_info *info)
     return ((unsigned long)mode);
 }
 
-static void hvm_set_conf_params(xc_interface *handle, uint32_t domid,
+#if defined(__i386__) || defined(__x86_64__)
+static void hvm_set_viridian_features(libxl__gc *gc, uint32_t domid,
+                                      libxl_domain_build_info *const info)
+{
+    uint64_t feature_mask = 0;
+    unsigned int i, n;
+
+    if (libxl_defbool_val(info->u.hvm.viridian)) {
+        LOG(DETAIL, "base+freq");
+        feature_mask = HVMPV_base_freq;
+        goto done;
+    }
+
+    n = libxl_integer_list_length(&info->u.hvm.viridian_enlightenments);
+
+    if (n != 0) {
+        feature_mask = HVMPV_no_freq;
+
+        for (i = 0; i < n; i++) {
+            libxl_viridian_enlightenment v;
+
+            v = libxl_integer_list_item(&info->u.hvm.viridian_enlightenments, i);
+
+            LOG(DETAIL, "+%s", libxl_viridian_enlightenment_to_string(v));
+
+            switch (v) {
+            case LIBXL_VIRIDIAN_ENLIGHTENMENT_BASE:
+                feature_mask |= HVMPV_base_freq;
+                break;
+            case LIBXL_VIRIDIAN_ENLIGHTENMENT_FREQ:
+                feature_mask &= ~HVMPV_no_freq;
+                break;
+            default:
+                LIBXL__LOG(CTX, LIBXL__LOG_WARNING,
+                           "Unknown viridian enlightenment %d\n",
+                           v);
+                break;
+            }
+        }
+    }
+
+done:
+    if (feature_mask != 0 &&
+        xc_hvm_param_set(CTX->xch,
+                         domid,
+                         HVM_PARAM_VIRIDIAN,
+                         feature_mask) != 0)
+        LIBXL__LOG_ERRNO(CTX, LIBXL__LOG_WARNING,
+                         "Couldn't set viridian feature mask (0x%"PRIx64")",
+                         feature_mask);
+}
+#endif
+
+static void hvm_set_conf_params(libxl__gc *gc, uint32_t domid,
                                 libxl_domain_build_info *const info)
 {
-    xc_hvm_param_set(handle, domid, HVM_PARAM_PAE_ENABLED,
+    xc_hvm_param_set(CTX->xch, domid, HVM_PARAM_PAE_ENABLED,
                     libxl_defbool_val(info->u.hvm.pae));
 #if defined(__i386__) || defined(__x86_64__)
-    xc_hvm_param_set(handle, domid, HVM_PARAM_VIRIDIAN,
-                    libxl_defbool_val(info->u.hvm.viridian));
-    xc_hvm_param_set(handle, domid, HVM_PARAM_HPET_ENABLED,
+    hvm_set_viridian_features(gc, domid, info);
+    xc_hvm_param_set(CTX->xch, domid, HVM_PARAM_HPET_ENABLED,
                     libxl_defbool_val(info->u.hvm.hpet));
 #endif
-    xc_hvm_param_set(handle, domid, HVM_PARAM_TIMER_MODE, timer_mode(info));
-    xc_hvm_param_set(handle, domid, HVM_PARAM_VPT_ALIGN,
+    xc_hvm_param_set(CTX->xch, domid, HVM_PARAM_TIMER_MODE,
+                     timer_mode(info));
+    xc_hvm_param_set(CTX->xch, domid, HVM_PARAM_VPT_ALIGN,
                     libxl_defbool_val(info->u.hvm.vpt_align));
-    xc_hvm_param_set(handle, domid, HVM_PARAM_NESTEDHVM,
+    xc_hvm_param_set(CTX->xch, domid, HVM_PARAM_NESTEDHVM,
                     libxl_defbool_val(info->u.hvm.nested_hvm));
 }
 
@@ -351,7 +404,7 @@ int libxl__build_pre(libxl__gc *gc, uint32_t domid,
     state->console_port = xc_evtchn_alloc_unbound(ctx->xch, domid, state->console_domid);
 
     if (info->type == LIBXL_DOMAIN_TYPE_HVM)
-        hvm_set_conf_params(ctx->xch, domid, info);
+        hvm_set_conf_params(gc, domid, info);
 
     rc = libxl__arch_domain_create(gc, d_config, domid);
 
diff --git a/tools/libxl/libxl_internal.h b/tools/libxl/libxl_internal.h
index beb052e..62188f2 100644
--- a/tools/libxl/libxl_internal.h
+++ b/tools/libxl/libxl_internal.h
@@ -3168,6 +3168,8 @@ int libxl__cpuid_policy_list_parse_json(libxl__gc *gc,
                                         libxl_cpuid_policy_list *p);
 int libxl__string_list_parse_json(libxl__gc *gc, const libxl__json_object *o,
                                   libxl_string_list *p);
+int libxl__integer_list_parse_json(libxl__gc *gc, const libxl__json_object *o,
+                                   libxl_integer_list *p);
 int libxl__key_value_list_parse_json(libxl__gc *gc,
                                      const libxl__json_object *o,
                                      libxl_key_value_list *p);
@@ -3207,6 +3209,11 @@ static inline int libxl__hwcap_is_default(libxl_hwcap *hwcap)
     return 0;
 }
 
+static inline int libxl__integer_list_is_empty(libxl_integer_list *pil)
+{
+    return !libxl_integer_list_length(pil);
+}
+
 static inline int libxl__string_list_is_empty(libxl_string_list *psl)
 {
     return !libxl_string_list_length(psl);
diff --git a/tools/libxl/libxl_json.c b/tools/libxl/libxl_json.c
index ceb014a..ffda84d 100644
--- a/tools/libxl/libxl_json.c
+++ b/tools/libxl/libxl_json.c
@@ -269,6 +269,56 @@ int libxl__key_value_list_parse_json(libxl__gc *gc, const libxl__json_object *o,
     return 0;
 }
 
+yajl_gen_status libxl_integer_list_gen_json(yajl_gen hand, libxl_integer_list *p)
+{
+    yajl_gen_status s;
+    int i;
+
+    s = yajl_gen_array_open(hand);
+    if (s != yajl_gen_status_ok) goto out;
+
+    if (p->count == 0) goto empty;
+
+    for (i = 0; i < p->count; i++) {
+        s = yajl_gen_integer(hand, p->array[i]);
+        if (s != yajl_gen_status_ok) goto out;
+    }
+empty:
+    s = yajl_gen_array_close(hand);
+out:
+    return s;
+}
+
+int libxl__integer_list_parse_json(libxl__gc *gc, const libxl__json_object *o,
+                                   libxl_integer_list *p)
+{
+    const libxl__json_object *t;
+    flexarray_t *array = NULL;
+    int i;
+
+    if (!libxl__json_object_is_array(o))
+        return ERROR_FAIL;
+
+    array = libxl__json_object_get_array(o);
+
+    if (array->count == 0) {
+        p->count = 0;
+        return 0;
+    }
+
+    p->count = array->count;
+    p->array = libxl__calloc(NOGC, p->count, sizeof(int));
+
+    for (i = 0; (t = libxl__json_array_get(o, i)); i++) {
+        if (!libxl__json_object_is_integer(t))
+            return ERROR_FAIL;
+
+        p->array[i] = libxl__json_object_get_integer(t);
+    }
+
+    return 0;
+}
+
 yajl_gen_status libxl_string_list_gen_json(yajl_gen hand, libxl_string_list *pl)
 {
     libxl_string_list l = *pl;
diff --git a/tools/libxl/libxl_json.h b/tools/libxl/libxl_json.h
index af26e78..63ef5a1 100644
--- a/tools/libxl/libxl_json.h
+++ b/tools/libxl/libxl_json.h
@@ -30,6 +30,7 @@ yajl_gen_status libxl_bitmap_gen_json(yajl_gen hand, libxl_bitmap *p);
 yajl_gen_status libxl_cpuid_policy_list_gen_json(yajl_gen hand,
                                                  libxl_cpuid_policy_list *p);
 yajl_gen_status libxl_string_list_gen_json(yajl_gen hand, libxl_string_list *p);
+yajl_gen_status libxl_integer_list_gen_json(yajl_gen hand, libxl_integer_list *p);
 yajl_gen_status libxl_key_value_list_gen_json(yajl_gen hand,
                                               libxl_key_value_list *p);
 yajl_gen_status libxl_hwcap_gen_json(yajl_gen hand, libxl_hwcap *p);
diff --git a/tools/libxl/libxl_types.idl b/tools/libxl/libxl_types.idl
index 0b3496f..3b0059c 100644
--- a/tools/libxl/libxl_types.idl
+++ b/tools/libxl/libxl_types.idl
@@ -22,6 +22,9 @@ libxl_cpuid_policy_list = Builtin("cpuid_policy_list", dispose_fn="libxl_cpuid_d
                                   json_parse_type="JSON_ARRAY", check_default_fn="libxl__cpuid_policy_is_empty",
                                   copy_fn="libxl_cpuid_policy_list_copy")
 
+libxl_integer_list = Builtin("integer_list", dispose_fn="libxl_integer_list_dispose", passby=PASS_BY_REFERENCE,
+                            json_parse_type="JSON_ARRAY", check_default_fn="libxl__integer_list_is_empty",
+                            copy_fn="libxl_integer_list_copy")
 libxl_string_list = Builtin("string_list", dispose_fn="libxl_string_list_dispose", passby=PASS_BY_REFERENCE,
                             json_parse_type="JSON_ARRAY", check_default_fn="libxl__string_list_is_empty",
                             copy_fn="libxl_string_list_copy")
@@ -175,6 +178,13 @@ libxl_vendor_device = Enumeration("vendor_device", [
     (0, "NONE"),
     (1, "XENSERVER"),
     ])
+
+libxl_viridian_enlightenment = Enumeration("viridian_enlightenment", [
+    (0, "unknown"),
+    (1, "base"),
+    (2, "freq"),
+    ])
+
 #
 # Complex libxl types
 #
@@ -364,7 +374,10 @@ libxl_domain_build_info = Struct("domain_build_info",[
                                        ("acpi_s3",          libxl_defbool),
                                        ("acpi_s4",          libxl_defbool),
                                        ("nx",               libxl_defbool),
+                                       # deprecated
                                        ("viridian",         libxl_defbool),
+                                       # see libxl_viridian_enlightenment for valid values
+                                       ("viridian_enlightenments", libxl_integer_list),
                                        ("timeoffset",       string),
                                        ("hpet",             libxl_defbool),
                                        ("vpt_align",        libxl_defbool),
diff --git a/tools/libxl/xl_cmdimpl.c b/tools/libxl/xl_cmdimpl.c
index f1c136a..5b41658 100644
--- a/tools/libxl/xl_cmdimpl.c
+++ b/tools/libxl/xl_cmdimpl.c
@@ -775,8 +775,8 @@ static void parse_config_data(const char *config_source,
     long l;
     XLU_Config *config;
     XLU_ConfigList *cpus, *vbds, *nics, *pcis, *cvfbs, *cpuids, *vtpms;
-    XLU_ConfigList *ioports, *irqs, *iomem;
-    int num_ioports, num_irqs, num_iomem, num_cpus;
+    XLU_ConfigList *ioports, *irqs, *iomem, *viridian;
+    int num_ioports, num_irqs, num_iomem, num_cpus, num_viridian;
     int pci_power_mgmt = 0;
     int pci_msitranslate = 0;
     int pci_permissive = 0;
@@ -993,10 +993,55 @@ static void parse_config_data(const char *config_source,
         xlu_cfg_get_defbool(config, "acpi_s3", &b_info->u.hvm.acpi_s3, 0);
         xlu_cfg_get_defbool(config, "acpi_s4", &b_info->u.hvm.acpi_s4, 0);
         xlu_cfg_get_defbool(config, "nx", &b_info->u.hvm.nx, 0);
-        xlu_cfg_get_defbool(config, "viridian", &b_info->u.hvm.viridian, 0);
         xlu_cfg_get_defbool(config, "hpet", &b_info->u.hvm.hpet, 0);
         xlu_cfg_get_defbool(config, "vpt_align", &b_info->u.hvm.vpt_align, 0);
 
+        libxl_integer_list_init(&b_info->u.hvm.viridian_enlightenments);
+
+        switch (xlu_cfg_get_list(config, "viridian",
+                                 &viridian, &num_viridian, 1))
+        {
+        case 0: /* Success */
+            for (i = 0; i < num_viridian; i++) {
+                libxl_viridian_enlightenment v;
+
+                buf = xlu_cfg_get_listitem(viridian, i);
+                e = libxl_viridian_enlightenment_from_string(buf, &v);
+                if (e) {
+                    fprintf(stderr,
+                            "xl: unknown viridian enlightenment '%s'\n",
+                            buf);
+                    exit(-ERROR_FAIL);
+                }
+
+                libxl_integer_list_append(ctx,
+                                          &b_info->u.hvm.viridian_enlightenments,
+                                          v);
+            }
+            break;
+        case ESRCH: break; /* Option not present */
+        case EINVAL: {
+            libxl_defbool b;
+
+            xlu_cfg_get_defbool(config, "viridian", &b, 1);
+            if (libxl_defbool_val(b)) {
+                fprintf(stderr, "WARNING: Specifying \"viridian\""
+                        " as a boolean is deprecated. "
+                        "Please use a list of features.\n");
+                libxl_integer_list_append(ctx,
+                                          &b_info->u.hvm.viridian_enlightenments,
+                                          LIBXL_VIRIDIAN_ENLIGHTENMENT_BASE);
+                libxl_integer_list_append(ctx,
+                                          &b_info->u.hvm.viridian_enlightenments,
+                                          LIBXL_VIRIDIAN_ENLIGHTENMENT_FREQ);
+            }
+            break;
+        }
+        default:
+            fprintf(stderr,"xl: Unable to parse viridian enlightenments.\n");
+            exit(-ERROR_FAIL);
+        }
+
         if (!xlu_cfg_get_long(config, "timer_mode", &l, 1)) {
             const char *s = libxl_timer_mode_to_string(l);
             fprintf(stderr, "WARNING: specifying \"timer_mode\" as an integer is deprecated. "
diff --git a/tools/ocaml/libs/xl/genwrap.py b/tools/ocaml/libs/xl/genwrap.py
index 402e489..5ef9010 100644
--- a/tools/ocaml/libs/xl/genwrap.py
+++ b/tools/ocaml/libs/xl/genwrap.py
@@ -15,6 +15,7 @@ builtins = {
     "libxl_uuid":           ("int array",              "Uuid_val(&%(c)s, %(o)s)",   "Val_uuid(&%(c)s)"),
     "libxl_bitmap":         ("bool array",             "Bitmap_val(ctx, &%(c)s, %(o)s)",   "Val_bitmap(&%(c)s)"),    
     "libxl_key_value_list": ("(string * string) list", "libxl_key_value_list_val(&%(c)s, %(o)s)", "Val_key_value_list(&%(c)s)"),
+    "libxl_integer_list":   ("int list",               "libxl_integer_list_val(&%(c)s, %(o)s)", "Val_integer_list(&%(c)s)"),
     "libxl_string_list":    ("string list",            "libxl_string_list_val(&%(c)s, %(o)s)", "Val_string_list(&%(c)s)"),
     "libxl_mac":            ("int array",              "Mac_val(&%(c)s, %(o)s)",    "Val_mac(&%(c)s)"),
     "libxl_hwcap":          ("int32 array",            None,                                "Val_hwcap(&%(c)s)"),
diff --git a/tools/ocaml/libs/xl/xenlight_stubs.c b/tools/ocaml/libs/xl/xenlight_stubs.c
index 4133527..0a73b95 100644
--- a/tools/ocaml/libs/xl/xenlight_stubs.c
+++ b/tools/ocaml/libs/xl/xenlight_stubs.c
@@ -189,6 +189,39 @@ static value Val_key_value_list(libxl_key_value_list *c_val)
 	CAMLreturn(list);
 }
 
+static int libxl_integer_list_val(libxl_integer_list *c_val, value v)
+{
+	CAMLparam1(v);
+	int i;
+	libxl_integer_list l;
+
+	l.count = list_len(v);
+
+	for (i = 0; v != Val_emptylist; i++, v = Field(v, 1) )
+		l.array[i] = Int_val(Field(v, 0));
+
+	*c_val = l;
+	CAMLreturn(0);
+}
+
+static value Val_integer_list(libxl_integer_list *c_val)
+{
+	CAMLparam0();
+	CAMLlocal3(list, cons, integer);
+	int i;
+
+	list = Val_emptylist;
+	for (i = c_val->count; i >= 0; i--) {
+		integer = caml_copy_nativeint(c_val->array[i]);
+		cons = caml_alloc(2, 0);
+		Store_field(cons, 0, integer);  // head
+		Store_field(cons, 1, list);     // tail
+		list = cons;
+	}
+
+	CAMLreturn(list);
+}
+
 static int libxl_string_list_val(libxl_string_list *c_val, value v)
 {
 	CAMLparam1(v);
diff --git a/tools/python/xen/lowlevel/xl/xl.c b/tools/python/xen/lowlevel/xl/xl.c
index 32f982a..9ee5451 100644
--- a/tools/python/xen/lowlevel/xl/xl.c
+++ b/tools/python/xen/lowlevel/xl/xl.c
@@ -265,6 +265,12 @@ int attrib__libxl_mac_set(PyObject *v, libxl_mac *pptr)
     return fixed_bytearray_set(v, *pptr, 6);
 }
 
+int attrib__libxl_integer_list_set(PyObject *v, libxl_integer_list *pptr)
+{
+    PyErr_SetString(PyExc_NotImplementedError, "Setting integer_list");
+    return -1;
+}
+
 int attrib__libxl_string_list_set(PyObject *v, libxl_string_list *pptr)
 {
     PyErr_SetString(PyExc_NotImplementedError, "Setting string_list");
diff --git a/xen/arch/x86/hvm/hvm.c b/xen/arch/x86/hvm/hvm.c
index 94b18ba..8aeb8a6 100644
--- a/xen/arch/x86/hvm/hvm.c
+++ b/xen/arch/x86/hvm/hvm.c
@@ -5554,8 +5554,24 @@ long do_hvm_op(unsigned long op, XEN_GUEST_HANDLE_PARAM(void) arg)
                     rc = -EINVAL;
                 break;
             case HVM_PARAM_VIRIDIAN:
-                if ( a.value > 1 )
+                /* This should only ever be set once by the tools and read by the guest. */
+                rc = -EPERM;
+                if ( curr_d == d )
+                    break;
+
+                if ( a.value != d->arch.hvm_domain.params[a.index] )
+                {
+                    rc = -EEXIST;
+                    if ( d->arch.hvm_domain.params[a.index] != 0 )
+                        break;
+
                     rc = -EINVAL;
+                    if ( (a.value & ~HVMPV_feature_mask) ||
+                         !(a.value & HVMPV_base_freq) )
+                        break;
+                }
+
+                rc = 0;
                 break;
             case HVM_PARAM_IDENT_PT:
                 /* Not reflexive, as we must domain_pause(). */
diff --git a/xen/arch/x86/hvm/viridian.c b/xen/arch/x86/hvm/viridian.c
index b646a8a..28c4479 100644
--- a/xen/arch/x86/hvm/viridian.c
+++ b/xen/arch/x86/hvm/viridian.c
@@ -90,8 +90,9 @@ int cpuid_viridian_leaves(unsigned int leaf, unsigned int *eax,
         /* Which hypervisor MSRs are available to the guest */
         *eax = (CPUID3A_MSR_APIC_ACCESS |
                 CPUID3A_MSR_HYPERCALL   |
-                CPUID3A_MSR_VP_INDEX    |
-                CPUID3A_MSR_FREQ);
+                CPUID3A_MSR_VP_INDEX);
+        if ( !(viridian_feature_mask(d) & HVMPV_no_freq) )
+            *eax |= CPUID3A_MSR_FREQ;
         break;
     case 4:
         /* Recommended hypercall usage. */
@@ -312,11 +313,17 @@ int rdmsr_viridian_regs(uint32_t idx, uint64_t *val)
         break;
 
     case VIRIDIAN_MSR_TSC_FREQUENCY:
+        if ( viridian_feature_mask(d) & HVMPV_no_freq )
+            return 0;
+
         perfc_incr(mshv_rdmsr_tsc_frequency);
         *val = (uint64_t)d->arch.tsc_khz * 1000ull;
         break;
 
     case VIRIDIAN_MSR_APIC_FREQUENCY:
+        if ( viridian_feature_mask(d) & HVMPV_no_freq )
+            return 0;
+
         perfc_incr(mshv_rdmsr_apic_frequency);
         *val = 1000000000ull / APIC_BUS_CYCLE_NS;
         break;
@@ -489,3 +496,13 @@ static int viridian_load_vcpu_ctxt(struct domain *d, hvm_domain_context_t *h)
 
 HVM_REGISTER_SAVE_RESTORE(VIRIDIAN_VCPU, viridian_save_vcpu_ctxt,
                           viridian_load_vcpu_ctxt, 1, HVMSR_PER_VCPU);
+
+/*
+ * Local variables:
+ * mode: C
+ * c-file-style: "BSD"
+ * c-basic-offset: 4
+ * tab-width: 4
+ * indent-tabs-mode: nil
+ * End:
+ */
diff --git a/xen/include/asm-x86/hvm/hvm.h b/xen/include/asm-x86/hvm/hvm.h
index 0ebd478..24e513b 100644
--- a/xen/include/asm-x86/hvm/hvm.h
+++ b/xen/include/asm-x86/hvm/hvm.h
@@ -344,8 +344,11 @@ static inline unsigned long hvm_get_shadow_gs_base(struct vcpu *v)
     return hvm_funcs.get_shadow_gs_base(v);
 }
 
-#define is_viridian_domain(_d)                                             \
- (is_hvm_domain(_d) && ((_d)->arch.hvm_domain.params[HVM_PARAM_VIRIDIAN]))
+#define viridian_feature_mask(d) \
+    ((d)->arch.hvm_domain.params[HVM_PARAM_VIRIDIAN])
+
+#define is_viridian_domain(d) \
+    (is_hvm_domain(d) && (viridian_feature_mask(d) & HVMPV_base_freq))
 
 void hvm_hypervisor_cpuid_leaf(uint32_t sub_idx,
                                uint32_t *eax, uint32_t *ebx,
diff --git a/xen/include/public/hvm/params.h b/xen/include/public/hvm/params.h
index 614ff5f..68d26fd 100644
--- a/xen/include/public/hvm/params.h
+++ b/xen/include/public/hvm/params.h
@@ -56,9 +56,40 @@
 
 #if defined(__i386__) || defined(__x86_64__)
 
-/* Expose Viridian interfaces to this HVM guest? */
+/*
+ * Viridian enlightenments
+ *
+ * (See http://download.microsoft.com/download/A/B/4/AB43A34E-BDD0-4FA6-BDEF-79EEF16E880B/Hypervisor%20Top%20Level%20Functional%20Specification%20v4.0.docx)
+ *
+ * To expose viridian enlightenments to the guest set this parameter
+ * to the desired feature mask. The base feature set must be present
+ * in any valid feature mask.
+ */
 #define HVM_PARAM_VIRIDIAN     9
 
+/* Base+Freq viridian feature sets:
+ *
+ * - Hypercall MSRs (HV_X64_MSR_GUEST_OS_ID and HV_X64_MSR_HYPERCALL)
+ * - APIC access MSRs (HV_X64_MSR_EOI, HV_X64_MSR_ICR and HV_X64_MSR_TPR)
+ * - Virtual Processor index MSR (HV_X64_MSR_VP_INDEX)
+ * - Timer frequency MSRs (HV_X64_MSR_TSC_FREQUENCY and
+ *   HV_X64_MSR_APIC_FREQUENCY)
+ */
+#define _HVMPV_base_freq 0
+#define HVMPV_base_freq  (1 << _HVMPV_base_freq)
+
+/* Feature set modifications */
+
+/* Disable timer frequency MSRs (HV_X64_MSR_TSC_FREQUENCY and
+ * HV_X64_MSR_APIC_FREQUENCY).
+ * This modification restores the viridian feature set to the
+ * original 'base' set exposed in releases prior to Xen 4.4.
+ */
+#define _HVMPV_no_freq 1
+#define HVMPV_no_freq  (1 << _HVMPV_no_freq)
+
+#define HVMPV_feature_mask (HVMPV_base_freq|HVMPV_no_freq)
+
 #endif
 
 /*
-- 
1.7.10.4

[PATCH v7 2/2] x86/viridian: Add partition time reference counter MSR support

[Paul Durrant]

This patch optionally re-instates support for the partition time reference
counter that was previously introduced by commit
e36cd2cdc9674a7a4855d21fb7b3e6e17c4bb33b and reverted by commit
1cd4fab14ce25859efa4a2af13475e6650a5506c. The previous implementation was
non-optional and flawed.

This implementation uses the tsc of vcpu0, which is preserved across
save/restore as part of the architectural state, and then converts that
to a 100ns tick using the domain's tsc_khz.

Signed-off-by: Paul Durrant <paul.durrant@citrix.com>
Cc: Keir Fraser <keir@xen.org>
Cc: Jan Beulich <jbeulich@suse.com>
Cc: Ian Campbell <ian.campbell@citrix.com>
Cc: Ian Jackson <ian.jackson@eu.citrix.com>
Cc: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Cc: Christoph Egger <chegger@amazon.de>
---
 docs/man/xl.cfg.pod.5            |    7 +++++++
 tools/libxl/libxl_dom.c          |    3 +++
 tools/libxl/libxl_types.idl      |    1 +
 xen/arch/x86/hvm/viridian.c      |   28 +++++++++++++++++++++++-----
 xen/arch/x86/time.c              |    4 ++--
 xen/include/asm-x86/perfc_defn.h |    1 +
 xen/include/asm-x86/time.h       |    4 ++++
 xen/include/public/hvm/params.h  |    9 ++++++++-
 8 files changed, 49 insertions(+), 8 deletions(-)

diff --git a/docs/man/xl.cfg.pod.5 b/docs/man/xl.cfg.pod.5
index d91f101..ac3798a 100644
--- a/docs/man/xl.cfg.pod.5
+++ b/docs/man/xl.cfg.pod.5
@@ -1131,6 +1131,13 @@ This set incorporates the TSC and APIC frequency MSRs.
 This enlightenment can improve performance of Windows 7 and Windows
 Server 2008 R2 onwards.
 
+=item B<time_ref_count>
+
+This set incorporates Partition Time Reference Counter MSR.
+
+This enlightenment can improve performance of Windows 8 and Windows
+Server 2012 onwards.
+
 =back
  
 See the latest version of Microsoft's Hypervisor Top-Level Functional
diff --git a/tools/libxl/libxl_dom.c b/tools/libxl/libxl_dom.c
index e854984..579188a 100644
--- a/tools/libxl/libxl_dom.c
+++ b/tools/libxl/libxl_dom.c
@@ -241,6 +241,9 @@ static void hvm_set_viridian_features(libxl__gc *gc, uint32_t domid,
             case LIBXL_VIRIDIAN_ENLIGHTENMENT_FREQ:
                 feature_mask &= ~HVMPV_no_freq;
                 break;
+            case LIBXL_VIRIDIAN_ENLIGHTENMENT_TIME_REF_COUNT:
+                feature_mask |= HVMPV_time_ref_count;
+                break;
             default:
                 LIBXL__LOG(CTX, LIBXL__LOG_WARNING,
                            "Unknown viridian enlightenment %d\n",
diff --git a/tools/libxl/libxl_types.idl b/tools/libxl/libxl_types.idl
index 3b0059c..a2a523e 100644
--- a/tools/libxl/libxl_types.idl
+++ b/tools/libxl/libxl_types.idl
@@ -183,6 +183,7 @@ libxl_viridian_enlightenment = Enumeration("viridian_enlightenment", [
     (0, "unknown"),
     (1, "base"),
     (2, "freq"),
+    (3, "time_ref_count"),
     ])
 
 #
diff --git a/xen/arch/x86/hvm/viridian.c b/xen/arch/x86/hvm/viridian.c
index 28c4479..04cd158 100644
--- a/xen/arch/x86/hvm/viridian.c
+++ b/xen/arch/x86/hvm/viridian.c
@@ -36,11 +36,11 @@
 #define HvNotifyLongSpinWait    8
 
 /* Viridian CPUID 4000003, Viridian MSR availability. */
-#define CPUID3A_MSR_REF_COUNT   (1 << 1)
-#define CPUID3A_MSR_APIC_ACCESS (1 << 4)
-#define CPUID3A_MSR_HYPERCALL   (1 << 5)
-#define CPUID3A_MSR_VP_INDEX    (1 << 6)
-#define CPUID3A_MSR_FREQ        (1 << 11)
+#define CPUID3A_MSR_TIME_REF_COUNT (1 << 1)
+#define CPUID3A_MSR_APIC_ACCESS    (1 << 4)
+#define CPUID3A_MSR_HYPERCALL      (1 << 5)
+#define CPUID3A_MSR_VP_INDEX       (1 << 6)
+#define CPUID3A_MSR_FREQ           (1 << 11)
 
 /* Viridian CPUID 4000004, Implementation Recommendations. */
 #define CPUID4A_MSR_BASED_APIC  (1 << 3)
@@ -93,6 +93,8 @@ int cpuid_viridian_leaves(unsigned int leaf, unsigned int *eax,
                 CPUID3A_MSR_VP_INDEX);
         if ( !(viridian_feature_mask(d) & HVMPV_no_freq) )
             *eax |= CPUID3A_MSR_FREQ;
+        if ( viridian_feature_mask(d) & HVMPV_time_ref_count )
+            *eax |= CPUID3A_MSR_TIME_REF_COUNT;
         break;
     case 4:
         /* Recommended hypercall usage. */
@@ -344,6 +346,22 @@ int rdmsr_viridian_regs(uint32_t idx, uint64_t *val)
         *val = v->arch.hvm_vcpu.viridian.apic_assist.raw;
         break;
 
+    case VIRIDIAN_MSR_TIME_REF_COUNT:
+    {
+        uint64_t tsc;
+        struct time_scale tsc_to_ns;
+
+        if ( !(viridian_feature_mask(d) & HVMPV_time_ref_count) )
+            return 0;
+
+        perfc_incr(mshv_rdmsr_time_ref_count);
+        tsc = hvm_get_guest_tsc(pt_global_vcpu_target(d));
+
+        /* convert tsc to count of 100ns periods */
+        set_time_scale(&tsc_to_ns, d->arch.tsc_khz * 1000);
+        *val = scale_delta(tsc, &tsc_to_ns) / 100ul;
+        break;
+    }
     default:
         return 0;
     }
diff --git a/xen/arch/x86/time.c b/xen/arch/x86/time.c
index bd89219..74c01e3 100644
--- a/xen/arch/x86/time.c
+++ b/xen/arch/x86/time.c
@@ -121,7 +121,7 @@ static inline u32 mul_frac(u32 multiplicand, u32 multiplier)
  * Scale a 64-bit delta by scaling and multiplying by a 32-bit fraction,
  * yielding a 64-bit result.
  */
-static inline u64 scale_delta(u64 delta, struct time_scale *scale)
+u64 scale_delta(u64 delta, struct time_scale *scale)
 {
     u64 product;
 
@@ -272,7 +272,7 @@ static u64 init_pit_and_calibrate_tsc(void)
     return ((end - start) * (u64)CALIBRATE_FRAC);
 }
 
-static void set_time_scale(struct time_scale *ts, u64 ticks_per_sec)
+void set_time_scale(struct time_scale *ts, u64 ticks_per_sec)
 {
     u64 tps64 = ticks_per_sec;
     u32 tps32;
diff --git a/xen/include/asm-x86/perfc_defn.h b/xen/include/asm-x86/perfc_defn.h
index 7d802cc..170da00 100644
--- a/xen/include/asm-x86/perfc_defn.h
+++ b/xen/include/asm-x86/perfc_defn.h
@@ -120,6 +120,7 @@ PERFCOUNTER(mshv_rdmsr_hc_page,         "MS Hv rdmsr hypercall page")
 PERFCOUNTER(mshv_rdmsr_vp_index,        "MS Hv rdmsr vp index")
 PERFCOUNTER(mshv_rdmsr_tsc_frequency,   "MS Hv rdmsr TSC frequency")
 PERFCOUNTER(mshv_rdmsr_apic_frequency,  "MS Hv rdmsr APIC frequency")
+PERFCOUNTER(mshv_rdmsr_time_ref_count,  "MS Hv rdmsr time ref count")
 PERFCOUNTER(mshv_rdmsr_icr,             "MS Hv rdmsr icr")
 PERFCOUNTER(mshv_rdmsr_tpr,             "MS Hv rdmsr tpr")
 PERFCOUNTER(mshv_rdmsr_apic_assist,     "MS Hv rdmsr APIC assist")
diff --git a/xen/include/asm-x86/time.h b/xen/include/asm-x86/time.h
index 420620e..c4d82f6 100644
--- a/xen/include/asm-x86/time.h
+++ b/xen/include/asm-x86/time.h
@@ -76,4 +76,8 @@ void cpuid_time_leaf(uint32_t sub_idx, uint32_t *eax, uint32_t *ebx,
 
 u64 stime2tsc(s_time_t stime);
 
+struct time_scale;
+void set_time_scale(struct time_scale *ts, u64 ticks_per_sec);
+u64 scale_delta(u64 delta, struct time_scale *scale);
+
 #endif /* __X86_TIME_H__ */
diff --git a/xen/include/public/hvm/params.h b/xen/include/public/hvm/params.h
index 68d26fd..3c51072 100644
--- a/xen/include/public/hvm/params.h
+++ b/xen/include/public/hvm/params.h
@@ -88,7 +88,14 @@
 #define _HVMPV_no_freq 1
 #define HVMPV_no_freq  (1 << _HVMPV_no_freq)
 
-#define HVMPV_feature_mask (HVMPV_base_freq|HVMPV_no_freq)
+/* Enable Partition Time Reference Counter (HV_X64_MSR_TIME_REF_COUNT) */
+#define _HVMPV_time_ref_count 2
+#define HVMPV_time_ref_count  (1 << _HVMPV_time_ref_count)
+
+#define HVMPV_feature_mask \
+	(HVMPV_base_freq | \
+	 HVMPV_no_freq | \
+	 HVMPV_time_ref_count)
 
 #endif
 
-- 
1.7.10.4

Re: [PATCH v7 2/2] x86/viridian: Add partition time reference counter MSR support

[Jan Beulich]

>>> On 27.08.14 at 17:44, <paul.durrant@citrix.com> wrote:
> This patch optionally re-instates support for the partition time reference
> counter that was previously introduced by commit
> e36cd2cdc9674a7a4855d21fb7b3e6e17c4bb33b and reverted by commit
> 1cd4fab14ce25859efa4a2af13475e6650a5506c. The previous implementation was
> non-optional and flawed.
> 
> This implementation uses the tsc of vcpu0, which is preserved across
> save/restore as part of the architectural state, and then converts that
> to a 100ns tick using the domain's tsc_khz.
> 
> Signed-off-by: Paul Durrant <paul.durrant@citrix.com>
> Cc: Keir Fraser <keir@xen.org>
> Cc: Jan Beulich <jbeulich@suse.com>
> Cc: Ian Campbell <ian.campbell@citrix.com>
> Cc: Ian Jackson <ian.jackson@eu.citrix.com>
> Cc: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
> Cc: Christoph Egger <chegger@amazon.de>
> ---
>  docs/man/xl.cfg.pod.5            |    7 +++++++
>  tools/libxl/libxl_dom.c          |    3 +++
>  tools/libxl/libxl_types.idl      |    1 +
>  xen/arch/x86/hvm/viridian.c      |   28 +++++++++++++++++++++++-----
>  xen/arch/x86/time.c              |    4 ++--
>  xen/include/asm-x86/perfc_defn.h |    1 +
>  xen/include/asm-x86/time.h       |    4 ++++
>  xen/include/public/hvm/params.h  |    9 ++++++++-
>  8 files changed, 49 insertions(+), 8 deletions(-)
> 
> diff --git a/docs/man/xl.cfg.pod.5 b/docs/man/xl.cfg.pod.5
> index d91f101..ac3798a 100644
> --- a/docs/man/xl.cfg.pod.5
> +++ b/docs/man/xl.cfg.pod.5
> @@ -1131,6 +1131,13 @@ This set incorporates the TSC and APIC frequency MSRs.
>  This enlightenment can improve performance of Windows 7 and Windows
>  Server 2008 R2 onwards.
>  
> +=item B<time_ref_count>
> +
> +This set incorporates Partition Time Reference Counter MSR.
> +
> +This enlightenment can improve performance of Windows 8 and Windows
> +Server 2012 onwards.
> +
>  =back
>   
>  See the latest version of Microsoft's Hypervisor Top-Level Functional
> diff --git a/tools/libxl/libxl_dom.c b/tools/libxl/libxl_dom.c
> index e854984..579188a 100644
> --- a/tools/libxl/libxl_dom.c
> +++ b/tools/libxl/libxl_dom.c
> @@ -241,6 +241,9 @@ static void hvm_set_viridian_features(libxl__gc *gc, 
> uint32_t domid,
>              case LIBXL_VIRIDIAN_ENLIGHTENMENT_FREQ:
>                  feature_mask &= ~HVMPV_no_freq;
>                  break;
> +            case LIBXL_VIRIDIAN_ENLIGHTENMENT_TIME_REF_COUNT:
> +                feature_mask |= HVMPV_time_ref_count;
> +                break;
>              default:
>                  LIBXL__LOG(CTX, LIBXL__LOG_WARNING,
>                             "Unknown viridian enlightenment %d\n",
> diff --git a/tools/libxl/libxl_types.idl b/tools/libxl/libxl_types.idl
> index 3b0059c..a2a523e 100644
> --- a/tools/libxl/libxl_types.idl
> +++ b/tools/libxl/libxl_types.idl
> @@ -183,6 +183,7 @@ libxl_viridian_enlightenment = 
> Enumeration("viridian_enlightenment", [
>      (0, "unknown"),
>      (1, "base"),
>      (2, "freq"),
> +    (3, "time_ref_count"),
>      ])
>  
>  #
> diff --git a/xen/arch/x86/hvm/viridian.c b/xen/arch/x86/hvm/viridian.c
> index 28c4479..04cd158 100644
> --- a/xen/arch/x86/hvm/viridian.c
> +++ b/xen/arch/x86/hvm/viridian.c
> @@ -36,11 +36,11 @@
>  #define HvNotifyLongSpinWait    8
>  
>  /* Viridian CPUID 4000003, Viridian MSR availability. */
> -#define CPUID3A_MSR_REF_COUNT   (1 << 1)
> -#define CPUID3A_MSR_APIC_ACCESS (1 << 4)
> -#define CPUID3A_MSR_HYPERCALL   (1 << 5)
> -#define CPUID3A_MSR_VP_INDEX    (1 << 6)
> -#define CPUID3A_MSR_FREQ        (1 << 11)
> +#define CPUID3A_MSR_TIME_REF_COUNT (1 << 1)
> +#define CPUID3A_MSR_APIC_ACCESS    (1 << 4)
> +#define CPUID3A_MSR_HYPERCALL      (1 << 5)
> +#define CPUID3A_MSR_VP_INDEX       (1 << 6)
> +#define CPUID3A_MSR_FREQ           (1 << 11)
>  
>  /* Viridian CPUID 4000004, Implementation Recommendations. */
>  #define CPUID4A_MSR_BASED_APIC  (1 << 3)
> @@ -93,6 +93,8 @@ int cpuid_viridian_leaves(unsigned int leaf, unsigned int 
> *eax,
>                  CPUID3A_MSR_VP_INDEX);
>          if ( !(viridian_feature_mask(d) & HVMPV_no_freq) )
>              *eax |= CPUID3A_MSR_FREQ;
> +        if ( viridian_feature_mask(d) & HVMPV_time_ref_count )
> +            *eax |= CPUID3A_MSR_TIME_REF_COUNT;
>          break;
>      case 4:
>          /* Recommended hypercall usage. */
> @@ -344,6 +346,22 @@ int rdmsr_viridian_regs(uint32_t idx, uint64_t *val)
>          *val = v->arch.hvm_vcpu.viridian.apic_assist.raw;
>          break;
>  
> +    case VIRIDIAN_MSR_TIME_REF_COUNT:
> +    {
> +        uint64_t tsc;
> +        struct time_scale tsc_to_ns;
> +
> +        if ( !(viridian_feature_mask(d) & HVMPV_time_ref_count) )
> +            return 0;
> +
> +        perfc_incr(mshv_rdmsr_time_ref_count);
> +        tsc = hvm_get_guest_tsc(pt_global_vcpu_target(d));
> +
> +        /* convert tsc to count of 100ns periods */
> +        set_time_scale(&tsc_to_ns, d->arch.tsc_khz * 1000);

While the second parameter of the function has type u64, nothing
forces the multiplication to be done at 64-bit width (and 4GHz or
beyond clock speed isn't plain impossible).

> +        *val = scale_delta(tsc, &tsc_to_ns) / 100ul;
> +        break;
> +    }
>      default:

I'm pretty sure I asked for a blank line to be added between the
closing brace and the default: before.

Jan

Re: [PATCH v7 2/2] x86/viridian: Add partition time reference counter MSR support

[Paul Durrant]

> -----Original Message-----
> From: Jan Beulich [mailto:JBeulich@suse.com]
> Sent: 27 August 2014 17:02
> To: Paul Durrant
> Cc: Christoph Egger; Ian Campbell; Ian Jackson; Stefano Stabellini; xen-
> devel@lists.xen.org; Keir (Xen.org)
> Subject: Re: [PATCH v7 2/2] x86/viridian: Add partition time reference
> counter MSR support
> 
> >>> On 27.08.14 at 17:44, <paul.durrant@citrix.com> wrote:
> > This patch optionally re-instates support for the partition time reference
> > counter that was previously introduced by commit
> > e36cd2cdc9674a7a4855d21fb7b3e6e17c4bb33b and reverted by commit
> > 1cd4fab14ce25859efa4a2af13475e6650a5506c. The previous
> implementation was
> > non-optional and flawed.
> >
> > This implementation uses the tsc of vcpu0, which is preserved across
> > save/restore as part of the architectural state, and then converts that
> > to a 100ns tick using the domain's tsc_khz.
> >
> > Signed-off-by: Paul Durrant <paul.durrant@citrix.com>
> > Cc: Keir Fraser <keir@xen.org>
> > Cc: Jan Beulich <jbeulich@suse.com>
> > Cc: Ian Campbell <ian.campbell@citrix.com>
> > Cc: Ian Jackson <ian.jackson@eu.citrix.com>
> > Cc: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
> > Cc: Christoph Egger <chegger@amazon.de>
> > ---
> >  docs/man/xl.cfg.pod.5            |    7 +++++++
> >  tools/libxl/libxl_dom.c          |    3 +++
> >  tools/libxl/libxl_types.idl      |    1 +
> >  xen/arch/x86/hvm/viridian.c      |   28 +++++++++++++++++++++++-----
> >  xen/arch/x86/time.c              |    4 ++--
> >  xen/include/asm-x86/perfc_defn.h |    1 +
> >  xen/include/asm-x86/time.h       |    4 ++++
> >  xen/include/public/hvm/params.h  |    9 ++++++++-
> >  8 files changed, 49 insertions(+), 8 deletions(-)
> >
> > diff --git a/docs/man/xl.cfg.pod.5 b/docs/man/xl.cfg.pod.5
> > index d91f101..ac3798a 100644
> > --- a/docs/man/xl.cfg.pod.5
> > +++ b/docs/man/xl.cfg.pod.5
> > @@ -1131,6 +1131,13 @@ This set incorporates the TSC and APIC
> frequency MSRs.
> >  This enlightenment can improve performance of Windows 7 and Windows
> >  Server 2008 R2 onwards.
> >
> > +=item B<time_ref_count>
> > +
> > +This set incorporates Partition Time Reference Counter MSR.
> > +
> > +This enlightenment can improve performance of Windows 8 and Windows
> > +Server 2012 onwards.
> > +
> >  =back
> >
> >  See the latest version of Microsoft's Hypervisor Top-Level Functional
> > diff --git a/tools/libxl/libxl_dom.c b/tools/libxl/libxl_dom.c
> > index e854984..579188a 100644
> > --- a/tools/libxl/libxl_dom.c
> > +++ b/tools/libxl/libxl_dom.c
> > @@ -241,6 +241,9 @@ static void hvm_set_viridian_features(libxl__gc *gc,
> > uint32_t domid,
> >              case LIBXL_VIRIDIAN_ENLIGHTENMENT_FREQ:
> >                  feature_mask &= ~HVMPV_no_freq;
> >                  break;
> > +            case LIBXL_VIRIDIAN_ENLIGHTENMENT_TIME_REF_COUNT:
> > +                feature_mask |= HVMPV_time_ref_count;
> > +                break;
> >              default:
> >                  LIBXL__LOG(CTX, LIBXL__LOG_WARNING,
> >                             "Unknown viridian enlightenment %d\n",
> > diff --git a/tools/libxl/libxl_types.idl b/tools/libxl/libxl_types.idl
> > index 3b0059c..a2a523e 100644
> > --- a/tools/libxl/libxl_types.idl
> > +++ b/tools/libxl/libxl_types.idl
> > @@ -183,6 +183,7 @@ libxl_viridian_enlightenment =
> > Enumeration("viridian_enlightenment", [
> >      (0, "unknown"),
> >      (1, "base"),
> >      (2, "freq"),
> > +    (3, "time_ref_count"),
> >      ])
> >
> >  #
> > diff --git a/xen/arch/x86/hvm/viridian.c b/xen/arch/x86/hvm/viridian.c
> > index 28c4479..04cd158 100644
> > --- a/xen/arch/x86/hvm/viridian.c
> > +++ b/xen/arch/x86/hvm/viridian.c
> > @@ -36,11 +36,11 @@
> >  #define HvNotifyLongSpinWait    8
> >
> >  /* Viridian CPUID 4000003, Viridian MSR availability. */
> > -#define CPUID3A_MSR_REF_COUNT   (1 << 1)
> > -#define CPUID3A_MSR_APIC_ACCESS (1 << 4)
> > -#define CPUID3A_MSR_HYPERCALL   (1 << 5)
> > -#define CPUID3A_MSR_VP_INDEX    (1 << 6)
> > -#define CPUID3A_MSR_FREQ        (1 << 11)
> > +#define CPUID3A_MSR_TIME_REF_COUNT (1 << 1)
> > +#define CPUID3A_MSR_APIC_ACCESS    (1 << 4)
> > +#define CPUID3A_MSR_HYPERCALL      (1 << 5)
> > +#define CPUID3A_MSR_VP_INDEX       (1 << 6)
> > +#define CPUID3A_MSR_FREQ           (1 << 11)
> >
> >  /* Viridian CPUID 4000004, Implementation Recommendations. */
> >  #define CPUID4A_MSR_BASED_APIC  (1 << 3)
> > @@ -93,6 +93,8 @@ int cpuid_viridian_leaves(unsigned int leaf, unsigned
> int
> > *eax,
> >                  CPUID3A_MSR_VP_INDEX);
> >          if ( !(viridian_feature_mask(d) & HVMPV_no_freq) )
> >              *eax |= CPUID3A_MSR_FREQ;
> > +        if ( viridian_feature_mask(d) & HVMPV_time_ref_count )
> > +            *eax |= CPUID3A_MSR_TIME_REF_COUNT;
> >          break;
> >      case 4:
> >          /* Recommended hypercall usage. */
> > @@ -344,6 +346,22 @@ int rdmsr_viridian_regs(uint32_t idx, uint64_t *val)
> >          *val = v->arch.hvm_vcpu.viridian.apic_assist.raw;
> >          break;
> >
> > +    case VIRIDIAN_MSR_TIME_REF_COUNT:
> > +    {
> > +        uint64_t tsc;
> > +        struct time_scale tsc_to_ns;
> > +
> > +        if ( !(viridian_feature_mask(d) & HVMPV_time_ref_count) )
> > +            return 0;
> > +
> > +        perfc_incr(mshv_rdmsr_time_ref_count);
> > +        tsc = hvm_get_guest_tsc(pt_global_vcpu_target(d));
> > +
> > +        /* convert tsc to count of 100ns periods */
> > +        set_time_scale(&tsc_to_ns, d->arch.tsc_khz * 1000);
> 
> While the second parameter of the function has type u64, nothing
> forces the multiplication to be done at 64-bit width (and 4GHz or
> beyond clock speed isn't plain impossible).
> 

True. The promotion will probably done afterwards; I'll add a cast to make sure it's done before.

> > +        *val = scale_delta(tsc, &tsc_to_ns) / 100ul;
> > +        break;
> > +    }
> >      default:
> 
> I'm pretty sure I asked for a blank line to be added between the
> closing brace and the default: before.

Oh, sorry. I'll add that.

  Paul

> 
> Jan

Re: [PATCH v7 2/2] x86/viridian: Add partition time reference counter MSR support

[Jan Beulich]

>>> On 27.08.14 at 18:09, <Paul.Durrant@citrix.com> wrote:
>>  -----Original Message-----
>> From: Jan Beulich [mailto:JBeulich@suse.com]
>> Sent: 27 August 2014 17:02
>> To: Paul Durrant
>> Cc: Christoph Egger; Ian Campbell; Ian Jackson; Stefano Stabellini; xen-
>> devel@lists.xen.org; Keir (Xen.org)
>> Subject: Re: [PATCH v7 2/2] x86/viridian: Add partition time reference
>> counter MSR support
>> 
>> >>> On 27.08.14 at 17:44, <paul.durrant@citrix.com> wrote:
>> > This patch optionally re-instates support for the partition time reference
>> > counter that was previously introduced by commit
>> > e36cd2cdc9674a7a4855d21fb7b3e6e17c4bb33b and reverted by commit
>> > 1cd4fab14ce25859efa4a2af13475e6650a5506c. The previous
>> implementation was
>> > non-optional and flawed.
>> >
>> > This implementation uses the tsc of vcpu0, which is preserved across
>> > save/restore as part of the architectural state, and then converts that
>> > to a 100ns tick using the domain's tsc_khz.
>> >
>> > Signed-off-by: Paul Durrant <paul.durrant@citrix.com>
>> > Cc: Keir Fraser <keir@xen.org>
>> > Cc: Jan Beulich <jbeulich@suse.com>
>> > Cc: Ian Campbell <ian.campbell@citrix.com>
>> > Cc: Ian Jackson <ian.jackson@eu.citrix.com>
>> > Cc: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
>> > Cc: Christoph Egger <chegger@amazon.de>
>> > ---
>> >  docs/man/xl.cfg.pod.5            |    7 +++++++
>> >  tools/libxl/libxl_dom.c          |    3 +++
>> >  tools/libxl/libxl_types.idl      |    1 +
>> >  xen/arch/x86/hvm/viridian.c      |   28 +++++++++++++++++++++++-----
>> >  xen/arch/x86/time.c              |    4 ++--
>> >  xen/include/asm-x86/perfc_defn.h |    1 +
>> >  xen/include/asm-x86/time.h       |    4 ++++
>> >  xen/include/public/hvm/params.h  |    9 ++++++++-
>> >  8 files changed, 49 insertions(+), 8 deletions(-)
>> >
>> > diff --git a/docs/man/xl.cfg.pod.5 b/docs/man/xl.cfg.pod.5
>> > index d91f101..ac3798a 100644
>> > --- a/docs/man/xl.cfg.pod.5
>> > +++ b/docs/man/xl.cfg.pod.5
>> > @@ -1131,6 +1131,13 @@ This set incorporates the TSC and APIC
>> frequency MSRs.
>> >  This enlightenment can improve performance of Windows 7 and Windows
>> >  Server 2008 R2 onwards.
>> >
>> > +=item B<time_ref_count>
>> > +
>> > +This set incorporates Partition Time Reference Counter MSR.
>> > +
>> > +This enlightenment can improve performance of Windows 8 and Windows
>> > +Server 2012 onwards.
>> > +
>> >  =back
>> >
>> >  See the latest version of Microsoft's Hypervisor Top-Level Functional
>> > diff --git a/tools/libxl/libxl_dom.c b/tools/libxl/libxl_dom.c
>> > index e854984..579188a 100644
>> > --- a/tools/libxl/libxl_dom.c
>> > +++ b/tools/libxl/libxl_dom.c
>> > @@ -241,6 +241,9 @@ static void hvm_set_viridian_features(libxl__gc *gc,
>> > uint32_t domid,
>> >              case LIBXL_VIRIDIAN_ENLIGHTENMENT_FREQ:
>> >                  feature_mask &= ~HVMPV_no_freq;
>> >                  break;
>> > +            case LIBXL_VIRIDIAN_ENLIGHTENMENT_TIME_REF_COUNT:
>> > +                feature_mask |= HVMPV_time_ref_count;
>> > +                break;
>> >              default:
>> >                  LIBXL__LOG(CTX, LIBXL__LOG_WARNING,
>> >                             "Unknown viridian enlightenment %d\n",
>> > diff --git a/tools/libxl/libxl_types.idl b/tools/libxl/libxl_types.idl
>> > index 3b0059c..a2a523e 100644
>> > --- a/tools/libxl/libxl_types.idl
>> > +++ b/tools/libxl/libxl_types.idl
>> > @@ -183,6 +183,7 @@ libxl_viridian_enlightenment =
>> > Enumeration("viridian_enlightenment", [
>> >      (0, "unknown"),
>> >      (1, "base"),
>> >      (2, "freq"),
>> > +    (3, "time_ref_count"),
>> >      ])
>> >
>> >  #
>> > diff --git a/xen/arch/x86/hvm/viridian.c b/xen/arch/x86/hvm/viridian.c
>> > index 28c4479..04cd158 100644
>> > --- a/xen/arch/x86/hvm/viridian.c
>> > +++ b/xen/arch/x86/hvm/viridian.c
>> > @@ -36,11 +36,11 @@
>> >  #define HvNotifyLongSpinWait    8
>> >
>> >  /* Viridian CPUID 4000003, Viridian MSR availability. */
>> > -#define CPUID3A_MSR_REF_COUNT   (1 << 1)
>> > -#define CPUID3A_MSR_APIC_ACCESS (1 << 4)
>> > -#define CPUID3A_MSR_HYPERCALL   (1 << 5)
>> > -#define CPUID3A_MSR_VP_INDEX    (1 << 6)
>> > -#define CPUID3A_MSR_FREQ        (1 << 11)
>> > +#define CPUID3A_MSR_TIME_REF_COUNT (1 << 1)
>> > +#define CPUID3A_MSR_APIC_ACCESS    (1 << 4)
>> > +#define CPUID3A_MSR_HYPERCALL      (1 << 5)
>> > +#define CPUID3A_MSR_VP_INDEX       (1 << 6)
>> > +#define CPUID3A_MSR_FREQ           (1 << 11)
>> >
>> >  /* Viridian CPUID 4000004, Implementation Recommendations. */
>> >  #define CPUID4A_MSR_BASED_APIC  (1 << 3)
>> > @@ -93,6 +93,8 @@ int cpuid_viridian_leaves(unsigned int leaf, unsigned
>> int
>> > *eax,
>> >                  CPUID3A_MSR_VP_INDEX);
>> >          if ( !(viridian_feature_mask(d) & HVMPV_no_freq) )
>> >              *eax |= CPUID3A_MSR_FREQ;
>> > +        if ( viridian_feature_mask(d) & HVMPV_time_ref_count )
>> > +            *eax |= CPUID3A_MSR_TIME_REF_COUNT;
>> >          break;
>> >      case 4:
>> >          /* Recommended hypercall usage. */
>> > @@ -344,6 +346,22 @@ int rdmsr_viridian_regs(uint32_t idx, uint64_t *val)
>> >          *val = v->arch.hvm_vcpu.viridian.apic_assist.raw;
>> >          break;
>> >
>> > +    case VIRIDIAN_MSR_TIME_REF_COUNT:
>> > +    {
>> > +        uint64_t tsc;
>> > +        struct time_scale tsc_to_ns;
>> > +
>> > +        if ( !(viridian_feature_mask(d) & HVMPV_time_ref_count) )
>> > +            return 0;
>> > +
>> > +        perfc_incr(mshv_rdmsr_time_ref_count);
>> > +        tsc = hvm_get_guest_tsc(pt_global_vcpu_target(d));
>> > +
>> > +        /* convert tsc to count of 100ns periods */
>> > +        set_time_scale(&tsc_to_ns, d->arch.tsc_khz * 1000);
>> 
>> While the second parameter of the function has type u64, nothing
>> forces the multiplication to be done at 64-bit width (and 4GHz or
>> beyond clock speed isn't plain impossible).
>> 
> 
> True. The promotion will probably done afterwards; I'll add a cast to make 
> sure it's done before.

Or perhaps rather than an ugly cast, just use 1000ULL?

Jan

Re: [PATCH v7 2/2] x86/viridian: Add partition time reference counter MSR support

[Paul Durrant]

> -----Original Message-----
> From: Jan Beulich [mailto:JBeulich@suse.com]
> Sent: 28 August 2014 08:34
> To: Paul Durrant
> Cc: Christoph Egger; Ian Campbell; Ian Jackson; Stefano Stabellini; xen-
> devel@lists.xen.org; Keir (Xen.org)
> Subject: RE: [PATCH v7 2/2] x86/viridian: Add partition time reference
> counter MSR support
> 
> >>> On 27.08.14 at 18:09, <Paul.Durrant@citrix.com> wrote:
> >>  -----Original Message-----
> >> From: Jan Beulich [mailto:JBeulich@suse.com]
> >> Sent: 27 August 2014 17:02
> >> To: Paul Durrant
> >> Cc: Christoph Egger; Ian Campbell; Ian Jackson; Stefano Stabellini; xen-
> >> devel@lists.xen.org; Keir (Xen.org)
> >> Subject: Re: [PATCH v7 2/2] x86/viridian: Add partition time reference
> >> counter MSR support
> >>
> >> >>> On 27.08.14 at 17:44, <paul.durrant@citrix.com> wrote:
> >> > This patch optionally re-instates support for the partition time reference
> >> > counter that was previously introduced by commit
> >> > e36cd2cdc9674a7a4855d21fb7b3e6e17c4bb33b and reverted by commit
> >> > 1cd4fab14ce25859efa4a2af13475e6650a5506c. The previous
> >> implementation was
> >> > non-optional and flawed.
> >> >
> >> > This implementation uses the tsc of vcpu0, which is preserved across
> >> > save/restore as part of the architectural state, and then converts that
> >> > to a 100ns tick using the domain's tsc_khz.
> >> >
> >> > Signed-off-by: Paul Durrant <paul.durrant@citrix.com>
> >> > Cc: Keir Fraser <keir@xen.org>
> >> > Cc: Jan Beulich <jbeulich@suse.com>
> >> > Cc: Ian Campbell <ian.campbell@citrix.com>
> >> > Cc: Ian Jackson <ian.jackson@eu.citrix.com>
> >> > Cc: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
> >> > Cc: Christoph Egger <chegger@amazon.de>
> >> > ---
> >> >  docs/man/xl.cfg.pod.5            |    7 +++++++
> >> >  tools/libxl/libxl_dom.c          |    3 +++
> >> >  tools/libxl/libxl_types.idl      |    1 +
> >> >  xen/arch/x86/hvm/viridian.c      |   28 +++++++++++++++++++++++-----
> >> >  xen/arch/x86/time.c              |    4 ++--
> >> >  xen/include/asm-x86/perfc_defn.h |    1 +
> >> >  xen/include/asm-x86/time.h       |    4 ++++
> >> >  xen/include/public/hvm/params.h  |    9 ++++++++-
> >> >  8 files changed, 49 insertions(+), 8 deletions(-)
> >> >
> >> > diff --git a/docs/man/xl.cfg.pod.5 b/docs/man/xl.cfg.pod.5
> >> > index d91f101..ac3798a 100644
> >> > --- a/docs/man/xl.cfg.pod.5
> >> > +++ b/docs/man/xl.cfg.pod.5
> >> > @@ -1131,6 +1131,13 @@ This set incorporates the TSC and APIC
> >> frequency MSRs.
> >> >  This enlightenment can improve performance of Windows 7 and
> Windows
> >> >  Server 2008 R2 onwards.
> >> >
> >> > +=item B<time_ref_count>
> >> > +
> >> > +This set incorporates Partition Time Reference Counter MSR.
> >> > +
> >> > +This enlightenment can improve performance of Windows 8 and
> Windows
> >> > +Server 2012 onwards.
> >> > +
> >> >  =back
> >> >
> >> >  See the latest version of Microsoft's Hypervisor Top-Level Functional
> >> > diff --git a/tools/libxl/libxl_dom.c b/tools/libxl/libxl_dom.c
> >> > index e854984..579188a 100644
> >> > --- a/tools/libxl/libxl_dom.c
> >> > +++ b/tools/libxl/libxl_dom.c
> >> > @@ -241,6 +241,9 @@ static void hvm_set_viridian_features(libxl__gc
> *gc,
> >> > uint32_t domid,
> >> >              case LIBXL_VIRIDIAN_ENLIGHTENMENT_FREQ:
> >> >                  feature_mask &= ~HVMPV_no_freq;
> >> >                  break;
> >> > +            case LIBXL_VIRIDIAN_ENLIGHTENMENT_TIME_REF_COUNT:
> >> > +                feature_mask |= HVMPV_time_ref_count;
> >> > +                break;
> >> >              default:
> >> >                  LIBXL__LOG(CTX, LIBXL__LOG_WARNING,
> >> >                             "Unknown viridian enlightenment %d\n",
> >> > diff --git a/tools/libxl/libxl_types.idl b/tools/libxl/libxl_types.idl
> >> > index 3b0059c..a2a523e 100644
> >> > --- a/tools/libxl/libxl_types.idl
> >> > +++ b/tools/libxl/libxl_types.idl
> >> > @@ -183,6 +183,7 @@ libxl_viridian_enlightenment =
> >> > Enumeration("viridian_enlightenment", [
> >> >      (0, "unknown"),
> >> >      (1, "base"),
> >> >      (2, "freq"),
> >> > +    (3, "time_ref_count"),
> >> >      ])
> >> >
> >> >  #
> >> > diff --git a/xen/arch/x86/hvm/viridian.c b/xen/arch/x86/hvm/viridian.c
> >> > index 28c4479..04cd158 100644
> >> > --- a/xen/arch/x86/hvm/viridian.c
> >> > +++ b/xen/arch/x86/hvm/viridian.c
> >> > @@ -36,11 +36,11 @@
> >> >  #define HvNotifyLongSpinWait    8
> >> >
> >> >  /* Viridian CPUID 4000003, Viridian MSR availability. */
> >> > -#define CPUID3A_MSR_REF_COUNT   (1 << 1)
> >> > -#define CPUID3A_MSR_APIC_ACCESS (1 << 4)
> >> > -#define CPUID3A_MSR_HYPERCALL   (1 << 5)
> >> > -#define CPUID3A_MSR_VP_INDEX    (1 << 6)
> >> > -#define CPUID3A_MSR_FREQ        (1 << 11)
> >> > +#define CPUID3A_MSR_TIME_REF_COUNT (1 << 1)
> >> > +#define CPUID3A_MSR_APIC_ACCESS    (1 << 4)
> >> > +#define CPUID3A_MSR_HYPERCALL      (1 << 5)
> >> > +#define CPUID3A_MSR_VP_INDEX       (1 << 6)
> >> > +#define CPUID3A_MSR_FREQ           (1 << 11)
> >> >
> >> >  /* Viridian CPUID 4000004, Implementation Recommendations. */
> >> >  #define CPUID4A_MSR_BASED_APIC  (1 << 3)
> >> > @@ -93,6 +93,8 @@ int cpuid_viridian_leaves(unsigned int leaf,
> unsigned
> >> int
> >> > *eax,
> >> >                  CPUID3A_MSR_VP_INDEX);
> >> >          if ( !(viridian_feature_mask(d) & HVMPV_no_freq) )
> >> >              *eax |= CPUID3A_MSR_FREQ;
> >> > +        if ( viridian_feature_mask(d) & HVMPV_time_ref_count )
> >> > +            *eax |= CPUID3A_MSR_TIME_REF_COUNT;
> >> >          break;
> >> >      case 4:
> >> >          /* Recommended hypercall usage. */
> >> > @@ -344,6 +346,22 @@ int rdmsr_viridian_regs(uint32_t idx, uint64_t
> *val)
> >> >          *val = v->arch.hvm_vcpu.viridian.apic_assist.raw;
> >> >          break;
> >> >
> >> > +    case VIRIDIAN_MSR_TIME_REF_COUNT:
> >> > +    {
> >> > +        uint64_t tsc;
> >> > +        struct time_scale tsc_to_ns;
> >> > +
> >> > +        if ( !(viridian_feature_mask(d) & HVMPV_time_ref_count) )
> >> > +            return 0;
> >> > +
> >> > +        perfc_incr(mshv_rdmsr_time_ref_count);
> >> > +        tsc = hvm_get_guest_tsc(pt_global_vcpu_target(d));
> >> > +
> >> > +        /* convert tsc to count of 100ns periods */
> >> > +        set_time_scale(&tsc_to_ns, d->arch.tsc_khz * 1000);
> >>
> >> While the second parameter of the function has type u64, nothing
> >> forces the multiplication to be done at 64-bit width (and 4GHz or
> >> beyond clock speed isn't plain impossible).
> >>
> >
> > True. The promotion will probably done afterwards; I'll add a cast to make
> > sure it's done before.
> 
> Or perhaps rather than an ugly cast, just use 1000ULL?
> 

Yes, that would be sufficient but I thought a cast would make it more obvious. I don't particularly care though. Are you ok with the cast as it is in the v8 patch?

  Paul

> Jan

Re: [PATCH v7 2/2] x86/viridian: Add partition time reference counter MSR support

[Jan Beulich]

>>> On 28.08.14 at 09:55, <Paul.Durrant@citrix.com> wrote:
> Yes, that would be sufficient but I thought a cast would make it more 
> obvious. I don't particularly care though. Are you ok with the cast as it is 
> in the v8 patch?

Hmm, you used a cast _and_ 1000ul. I'm fine with that (i.e. no need
to resubmit), but it's clearly redundant (i.e. I may edit it before
committing).

Jan