[PATCH v12 0/2] x86/viridian improvements

[PATCH v12 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.

v8:
- Changes to patch #2 only:
  - Fixed 32- to 64-bit type promotion issue as pointed out by
    Jan Beulich

v9:
- Changes to ocaml stubs in patch #1 only
  - There was a missing calloc in the libxl_integer_list ocaml stubs

v10:
- Toolstack changes only:
  - Re-worked toolstack code after discussion with Ian C and Ian J.
    See http://lists.xen.org/archives/html/xen-devel/2014-09/msg00416.html

v11:
- Toolstack changes only:
  - Re-worked toolstack code after further discussion with Ian J.

v12:
- Toolstack changes in patch #1 requested by Ian C
  - Bitfield width now #defined
- Remove cast from patch #2 as requested by Jan

[PATCH v12 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 list so
that the sets can be individually enabled or disabled. For compatibility,
if the option is specified as a boolean, then a true (1) value will enable
the base and freq sets and a false (0) value will not enable any
enlightenments.

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 modified (only
re-written with the same value), 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           |   68 +++++++++++++++++++++++++++------
 tools/libxc/xc_domain_restore.c |    4 +-
 tools/libxl/libxl.h             |    7 ++++
 tools/libxl/libxl_dom.c         |   79 +++++++++++++++++++++++++++++++++++++--
 tools/libxl/libxl_types.idl     |    8 ++++
 tools/libxl/xl_cmdimpl.c        |   55 +++++++++++++++++++++++++--
 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 +++++++++++++++-
 10 files changed, 274 insertions(+), 26 deletions(-)

diff --git a/docs/man/xl.cfg.pod.5 b/docs/man/xl.cfg.pod.5
index 517ae2f..1bc7fbc 100644
--- a/docs/man/xl.cfg.pod.5
+++ b/docs/man/xl.cfg.pod.5
@@ -1134,18 +1134,62 @@ 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=[ "GROUP", "GROUP", ...]>
+
+The groups of Microsoft Hyper-V (AKA viridian) compatible enlightenments
+exposed to the guest. The following groups of enlightenments may be
+specified:
+
+=over 4
+
+=item B<base>
+
+This group incorporates the Hypercall MSRs, Virtual processor index MSR,
+and APIC access MSRs. These enlightenments can improve performance of
+Windows Vista and Windows Server 2008 onwards and setting this option
+for such guests is strongly recommended.
+This group is also a pre-requisite for all others. If it is disabled
+then it is an error to attempt to enable any other group.
+
+=item B<freq>
+
+This group incorporates the TSC and APIC frequency MSRs. These
+enlightenments can improve performance of Windows 7 and Windows
+Server 2008 R2 onwards.
+
+=item B<defaults>
+
+This is a special value that enables the default set of groups, which
+is currently the B<base> and B<freq> groups.
+
+=item B<all>
+
+This is a special value that enables all available groups.
+
+=back
+
+Groups can be disabled by prefixing the name with '!'. So, for example,
+to enable all groups except B<freq>, specify:
+
+=over 4
+
+B<viridian=[ "all", "!freq" ]>
+
+=back
+
+For details of the enlightenments see the latest version of Microsoft's
+Hypervisor Top-Level Functional Specification.
+
+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.
+
+The viridian option can be specified as a boolean. A value of true (1)
+is equivalent to the list [ "defaults" ], and a value of false (0) is
+equivalent to an empty list.
 
 =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/libxl.h b/tools/libxl/libxl.h
index bc68cac..10be7ca 100644
--- a/tools/libxl/libxl.h
+++ b/tools/libxl/libxl.h
@@ -145,6 +145,13 @@
 #define LIBXL_HAVE_BUILDINFO_IOMEM_START_GFN 1
 
 /*
+ * libxl_domain_build_info has u.hvm.viridian_enable and _disable bitmaps
+ * of the specified width.
+ */
+#define LIBXL_HAVE_BUILDINFO_HVM_VIRIDIAN_ENABLE_DISABLE 1
+#define LIBXL_BUILDINFO_HVM_VIRIDIAN_ENABLE_DISABLE_WIDTH 64
+
+/*
  * libxl ABI compatibility
  *
  * The only guarantee which libxl makes regarding ABI compatibility
diff --git a/tools/libxl/libxl_dom.c b/tools/libxl/libxl_dom.c
index ce0c4ac..2c500ca 100644
--- a/tools/libxl/libxl_dom.c
+++ b/tools/libxl/libxl_dom.c
@@ -209,14 +209,81 @@ static unsigned long timer_mode(const libxl_domain_build_info *info)
     return ((unsigned long)mode);
 }
 
+#if defined(__i386__) || defined(__x86_64__)
+static int hvm_set_viridian_features(libxl__gc *gc, uint32_t domid,
+                                     libxl_domain_build_info *const info)
+{
+    libxl_bitmap enlightenments;
+    libxl_viridian_enlightenment v;
+    uint64_t mask = 0;
+
+    libxl_bitmap_init(&enlightenments);
+    libxl_bitmap_alloc(CTX, &enlightenments,
+                       LIBXL_BUILDINFO_HVM_VIRIDIAN_ENABLE_DISABLE_WIDTH);
+
+    if (libxl_defbool_val(info->u.hvm.viridian)) {
+        /* Enable defaults */
+        libxl_bitmap_set(&enlightenments, LIBXL_VIRIDIAN_ENLIGHTENMENT_BASE);
+        libxl_bitmap_set(&enlightenments, LIBXL_VIRIDIAN_ENLIGHTENMENT_FREQ);
+    }
+
+    libxl_for_each_set_bit(v, info->u.hvm.viridian_enable) {
+        if (libxl_bitmap_test(&info->u.hvm.viridian_disable, v)) {
+            LIBXL__LOG(CTX, LIBXL__LOG_ERROR, "%s group both enabled and disabled",
+                       libxl_viridian_enlightenment_to_string(v));
+            goto err;
+        }
+        if (libxl_viridian_enlightenment_to_string(v)) /* check validity */
+            libxl_bitmap_set(&enlightenments, v);
+    }
+
+    libxl_for_each_set_bit(v, info->u.hvm.viridian_disable)
+        if (libxl_viridian_enlightenment_to_string(v)) /* check validity */
+            libxl_bitmap_reset(&enlightenments, v);
+
+    /* The base set is a pre-requisite for all others */
+    if (!libxl_bitmap_is_empty(&enlightenments) &&
+        !libxl_bitmap_test(&enlightenments, LIBXL_VIRIDIAN_ENLIGHTENMENT_BASE)) {
+        LIBXL__LOG(CTX, LIBXL__LOG_ERROR, "base group not enabled");
+        goto err;
+    }
+
+    libxl_for_each_set_bit(v, enlightenments)
+        LOG(DETAIL, "%s group enabled", libxl_viridian_enlightenment_to_string(v));
+
+    if (libxl_bitmap_test(&enlightenments, LIBXL_VIRIDIAN_ENLIGHTENMENT_BASE)) {
+        mask |= HVMPV_base_freq;
+
+        if (!libxl_bitmap_test(&enlightenments, LIBXL_VIRIDIAN_ENLIGHTENMENT_FREQ))
+            mask |= HVMPV_no_freq;
+    }
+
+    if (mask != 0 &&
+        xc_hvm_param_set(CTX->xch,
+                         domid,
+                         HVM_PARAM_VIRIDIAN,
+                         mask) != 0) {
+        LIBXL__LOG_ERRNO(CTX, LIBXL__LOG_ERROR,
+                         "Couldn't set viridian feature mask (0x%"PRIx64")",
+                         mask);
+        goto err;
+    }
+
+    libxl_bitmap_dispose(&enlightenments);
+    return 0;
+
+err:
+    libxl_bitmap_dispose(&enlightenments);
+    return ERROR_FAIL;
+}
+#endif
+
 static void hvm_set_conf_params(xc_interface *handle, uint32_t domid,
                                 libxl_domain_build_info *const info)
 {
     xc_hvm_param_set(handle, 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,
                     libxl_defbool_val(info->u.hvm.hpet));
 #endif
@@ -350,8 +417,14 @@ int libxl__build_pre(libxl__gc *gc, uint32_t domid,
     state->store_port = xc_evtchn_alloc_unbound(ctx->xch, domid, state->store_domid);
     state->console_port = xc_evtchn_alloc_unbound(ctx->xch, domid, state->console_domid);
 
-    if (info->type == LIBXL_DOMAIN_TYPE_HVM)
+    if (info->type == LIBXL_DOMAIN_TYPE_HVM) {
         hvm_set_conf_params(ctx->xch, domid, info);
+#if defined(__i386__) || defined(__x86_64__)
+        rc = hvm_set_viridian_features(gc, domid, info);
+        if (rc)
+            return rc;
+#endif
+    }
 
     rc = libxl__arch_domain_create(gc, d_config, domid);
 
diff --git a/tools/libxl/libxl_types.idl b/tools/libxl/libxl_types.idl
index f1fcbc3..1614b11 100644
--- a/tools/libxl/libxl_types.idl
+++ b/tools/libxl/libxl_types.idl
@@ -178,6 +178,12 @@ libxl_vendor_device = Enumeration("vendor_device", [
     (0, "NONE"),
     (1, "XENSERVER"),
     ])
+
+libxl_viridian_enlightenment = Enumeration("viridian_enlightenment", [
+    (0, "base"),
+    (1, "freq"),
+    ])
+
 #
 # Complex libxl types
 #
@@ -375,6 +381,8 @@ libxl_domain_build_info = Struct("domain_build_info",[
                                        ("acpi_s4",          libxl_defbool),
                                        ("nx",               libxl_defbool),
                                        ("viridian",         libxl_defbool),
+                                       ("viridian_enable",  libxl_bitmap),
+                                       ("viridian_disable", libxl_bitmap),
                                        ("timeoffset",       string),
                                        ("hpet",             libxl_defbool),
                                        ("vpt_align",        libxl_defbool),
diff --git a/tools/libxl/xl_cmdimpl.c b/tools/libxl/xl_cmdimpl.c
index 698b3bc..9a46345 100644
--- a/tools/libxl/xl_cmdimpl.c
+++ b/tools/libxl/xl_cmdimpl.c
@@ -808,8 +808,8 @@ 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;
@@ -1034,10 +1034,59 @@ 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);
 
+        switch (xlu_cfg_get_list(config, "viridian",
+                                 &viridian, &num_viridian, 1))
+        {
+        case 0: /* Success */
+            if (num_viridian) {
+                libxl_bitmap_alloc(ctx, &b_info->u.hvm.viridian_enable,
+                                   LIBXL_BUILDINFO_HVM_VIRIDIAN_ENABLE_DISABLE_WIDTH);
+                libxl_bitmap_alloc(ctx, &b_info->u.hvm.viridian_disable,
+                                   LIBXL_BUILDINFO_HVM_VIRIDIAN_ENABLE_DISABLE_WIDTH);
+            }
+            for (i = 0; i < num_viridian; i++) {
+                libxl_viridian_enlightenment v;
+
+                buf = xlu_cfg_get_listitem(viridian, i);
+                if (strcmp(buf, "all") == 0)
+                    libxl_bitmap_set_any(&b_info->u.hvm.viridian_enable);
+                else if (strcmp(buf, "defaults") == 0)
+                    libxl_defbool_set(&b_info->u.hvm.viridian, true);
+                else {
+                    libxl_bitmap *s = &b_info->u.hvm.viridian_enable;
+                    libxl_bitmap *r = &b_info->u.hvm.viridian_disable;
+
+                    if (*buf == '!') {
+                        s = &b_info->u.hvm.viridian_disable;
+                        r = &b_info->u.hvm.viridian_enable;
+                        buf++;
+                    }
+
+                    e = libxl_viridian_enlightenment_from_string(buf, &v);
+                    if (e) {
+                        fprintf(stderr,
+                                "xl: unknown viridian enlightenment '%s'\n",
+                                buf);
+                        exit(-ERROR_FAIL);
+                    }
+
+                    libxl_bitmap_set(s, v);
+                    libxl_bitmap_reset(r, v);
+                }
+            }
+            break;
+        case ESRCH: break; /* Option not present */
+        case EINVAL:
+            xlu_cfg_get_defbool(config, "viridian", &b_info->u.hvm.viridian, 1);
+            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/xen/arch/x86/hvm/hvm.c b/xen/arch/x86/hvm/hvm.c
index bb45593..5c7e0a4 100644
--- a/xen/arch/x86/hvm/hvm.c
+++ b/xen/arch/x86/hvm/hvm.c
@@ -5555,8 +5555,24 @@ 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 121d053..3e66276 100644
--- a/xen/include/asm-x86/hvm/hvm.h
+++ b/xen/include/asm-x86/hvm/hvm.h
@@ -346,8 +346,11 @@ 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 v12 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>
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: Christoph Egger <chegger@amazon.de>
---
 docs/man/xl.cfg.pod.5            |    8 +++++++-
 tools/libxl/libxl_dom.c          |    4 ++++
 tools/libxl/libxl_types.idl      |    1 +
 xen/arch/x86/hvm/viridian.c      |   29 ++++++++++++++++++++++++-----
 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, 51 insertions(+), 9 deletions(-)

diff --git a/docs/man/xl.cfg.pod.5 b/docs/man/xl.cfg.pod.5
index 1bc7fbc..8bba21c 100644
--- a/docs/man/xl.cfg.pod.5
+++ b/docs/man/xl.cfg.pod.5
@@ -1157,10 +1157,16 @@ This group incorporates the TSC and APIC frequency MSRs. These
 enlightenments can improve performance of Windows 7 and Windows
 Server 2008 R2 onwards.
 
+=item B<time_ref_count>
+
+This group incorporates Partition Time Reference Counter MSR. This
+enlightenment can improve performance of Windows 8 and Windows
+Server 2012 onwards.
+
 =item B<defaults>
 
 This is a special value that enables the default set of groups, which
-is currently the B<base> and B<freq> groups.
+is currently the B<base>, B<freq> and B<time_ref_count> groups.
 
 =item B<all>
 
diff --git a/tools/libxl/libxl_dom.c b/tools/libxl/libxl_dom.c
index 2c500ca..bd21841 100644
--- a/tools/libxl/libxl_dom.c
+++ b/tools/libxl/libxl_dom.c
@@ -225,6 +225,7 @@ static int hvm_set_viridian_features(libxl__gc *gc, uint32_t domid,
         /* Enable defaults */
         libxl_bitmap_set(&enlightenments, LIBXL_VIRIDIAN_ENLIGHTENMENT_BASE);
         libxl_bitmap_set(&enlightenments, LIBXL_VIRIDIAN_ENLIGHTENMENT_FREQ);
+        libxl_bitmap_set(&enlightenments, LIBXL_VIRIDIAN_ENLIGHTENMENT_TIME_REF_COUNT);
     }
 
     libxl_for_each_set_bit(v, info->u.hvm.viridian_enable) {
@@ -258,6 +259,9 @@ static int hvm_set_viridian_features(libxl__gc *gc, uint32_t domid,
             mask |= HVMPV_no_freq;
     }
 
+    if (libxl_bitmap_test(&enlightenments, LIBXL_VIRIDIAN_ENLIGHTENMENT_TIME_REF_COUNT))
+        mask |= HVMPV_time_ref_count;
+
     if (mask != 0 &&
         xc_hvm_param_set(CTX->xch,
                          domid,
diff --git a/tools/libxl/libxl_types.idl b/tools/libxl/libxl_types.idl
index 1614b11..90d152f 100644
--- a/tools/libxl/libxl_types.idl
+++ b/tools/libxl/libxl_types.idl
@@ -182,6 +182,7 @@ libxl_vendor_device = Enumeration("vendor_device", [
 libxl_viridian_enlightenment = Enumeration("viridian_enlightenment", [
     (0, "base"),
     (1, "freq"),
+    (2, "time_ref_count"),
     ])
 
 #
diff --git a/xen/arch/x86/hvm/viridian.c b/xen/arch/x86/hvm/viridian.c
index 28c4479..6726168 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 +346,23 @@ 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 * 1000ul);
+        *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 v12 0/2] x86/viridian improvements

[Ian Campbell]

On Tue, 2014-09-23 at 11:40 +0100, Paul Durrant wrote:
> This patch series incorporates several improvements to the code
> supporting viridian (i.e. hyper-v compatible) enlightenments for
> Windows guests:

Applied, thanks.

Re: [PATCH v12 0/2] x86/viridian improvements

[Paul Durrant]

> -----Original Message-----
> From: Ian Campbell
> Sent: 23 September 2014 15:32
> To: Paul Durrant
> Cc: xen-devel@lists.xen.org
> Subject: Re: [Xen-devel] [PATCH v12 0/2] x86/viridian improvements
> 
> On Tue, 2014-09-23 at 11:40 +0100, Paul Durrant wrote:
> > This patch series incorporates several improvements to the code
> > supporting viridian (i.e. hyper-v compatible) enlightenments for
> > Windows guests:
> 
> Applied, thanks.
> 

Thanks :-)

  Paul

Re: [PATCH v12 1/2] x86/viridian: Re-purpose the HVM parameter to be a feature mask

[Ian Jackson]

Paul Durrant writes ("[PATCH v12 1/2] x86/viridian: Re-purpose the HVM parameter to be a feature mask"):
> The following commits introduced the time reference counter MSR and
> TSC/APIC frequency MSRs into the viridian feature set respectively:
> 
> e36cd2cdc9674a7a4855d21fb7b3e6e17c4bb33b
> 84657efd9116f40924aa13c9d5a349e007da716f

For the tools parts:

Acked-by: Ian Jackson <ian.jackson@eu.citrix.com>

Ian.

Re: [PATCH v12 2/2] x86/viridian: Add partition time reference counter MSR support

[Ian Jackson]

Paul Durrant writes ("[PATCH v12 2/2] x86/viridian: Add partition time reference counter MSR support"):
> 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>
> Acked-by: Jan Beulich <jbeulich@suse.com>

For the tools parts:

Acked-by: Ian Jackson <ian.jackson@eu.citrix.com>

Ian.