[V3 PATCH 0/3]: PVH xen tools: tools changes to create PVH guest

[V3 PATCH 0/3]: PVH xen tools: tools changes to create PVH guest

[Mukesh Rathor]

Please find V3 tools changes for PVH. These were built on unstable c/s:
de333b694591909787da54a40496fc82c8ba5b62

Dropping the last xenxtore patch in V3. We can always add that in future
if needed.

A quick intro for the uninformed, these are patches for tools changes
to support creation of a PVH guest. A PVH guest is a PV guest that
runs in an HVM container. Note, at present HAP is required, and also
only a 64bit PV can run in PVH mode. A PVH guest is created by 
specifying pvh=1 in the config file. 

thanks,
Mukesh

[V3 PATCH 1/3] PVH xen tools: In Elf code, check hvm callback vector

[Mukesh Rathor]

 Add XENFEAT_hvm_callback_vector to elf_xen_feature_names
 so we can ensure the kernel supports all features required for
 PVH mode when building a PVH domU here. Note, hvm callback is
 required for PVH.

Signed-off-by: Mukesh Rathor <mukesh.rathor@oracle.com>
Acked-by: Ian Campbell <ian.campbell@citrix.com>
---
 xen/common/libelf/libelf-dominfo.c |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)

diff --git a/xen/common/libelf/libelf-dominfo.c b/xen/common/libelf/libelf-dominfo.c
index e79b339..25dd892 100644
--- a/xen/common/libelf/libelf-dominfo.c
+++ b/xen/common/libelf/libelf-dominfo.c
@@ -27,6 +27,7 @@ static const char *const elf_xen_feature_names[] = {
     [XENFEAT_auto_translated_physmap] = "auto_translated_physmap",
     [XENFEAT_supervisor_mode_kernel] = "supervisor_mode_kernel",
     [XENFEAT_pae_pgdir_above_4gb] = "pae_pgdir_above_4gb",
+    [XENFEAT_hvm_callback_vector] = "hvm_callback_vector",
     [XENFEAT_dom0] = "dom0"
 };
 static const unsigned elf_xen_features =
-- 
1.7.2.3

[V3 PATCH 2/3] PVH xen tools: libxc changes to build a PVH guest.

[Mukesh Rathor]

Signed-off-by: Mukesh Rathor <mukesh.rathor@oracle.com>
-----
V2: Make pvh_features string const, and fail 32bit PVH guest creation.
    Move PVH check to xc_dom_gnttab_init().
V3: let xc_dom_gnttab_hvm_seed be called for PVH.
---
 tools/libxc/xc_dom.h      |    1 +
 tools/libxc/xc_dom_core.c |    9 ++++
 tools/libxc/xc_dom_x86.c  |   90 +++++++++++++++++++++++++++++---------------
 3 files changed, 69 insertions(+), 31 deletions(-)

diff --git a/tools/libxc/xc_dom.h b/tools/libxc/xc_dom.h
index 86e23ee..5168bcd 100644
--- a/tools/libxc/xc_dom.h
+++ b/tools/libxc/xc_dom.h
@@ -130,6 +130,7 @@ struct xc_dom_image {
     domid_t console_domid;
     domid_t xenstore_domid;
     xen_pfn_t shared_info_mfn;
+    int pvh_enabled;
 
     xc_interface *xch;
     domid_t guest_domid;
diff --git a/tools/libxc/xc_dom_core.c b/tools/libxc/xc_dom_core.c
index 0f367f6..faa7e0f 100644
--- a/tools/libxc/xc_dom_core.c
+++ b/tools/libxc/xc_dom_core.c
@@ -766,6 +766,15 @@ int xc_dom_parse_image(struct xc_dom_image *dom)
         goto err;
     }
 
+    if ( dom->pvh_enabled )
+    {
+        const char *pvh_features = "writable_descriptor_tables|"
+                                   "auto_translated_physmap|"
+                                   "supervisor_mode_kernel|"
+                                   "hvm_callback_vector";
+        elf_xen_parse_features(pvh_features, dom->f_requested, NULL);
+    }
+
     /* check features */
     for ( i = 0; i < XENFEAT_NR_SUBMAPS; i++ )
     {
diff --git a/tools/libxc/xc_dom_x86.c b/tools/libxc/xc_dom_x86.c
index 126c0f8..fcc9d87 100644
--- a/tools/libxc/xc_dom_x86.c
+++ b/tools/libxc/xc_dom_x86.c
@@ -415,7 +415,8 @@ static int setup_pgtables_x86_64(struct xc_dom_image *dom)
         pgpfn = (addr - dom->parms.virt_base) >> PAGE_SHIFT_X86;
         l1tab[l1off] =
             pfn_to_paddr(xc_dom_p2m_guest(dom, pgpfn)) | L1_PROT;
-        if ( (addr >= dom->pgtables_seg.vstart) && 
+        if ( (!dom->pvh_enabled)                &&
+             (addr >= dom->pgtables_seg.vstart) &&
              (addr < dom->pgtables_seg.vend) )
             l1tab[l1off] &= ~_PAGE_RW; /* page tables are r/o */
         if ( l1off == (L1_PAGETABLE_ENTRIES_X86_64 - 1) )
@@ -587,6 +588,13 @@ static int vcpu_x86_32(struct xc_dom_image *dom, void *ptr)
 
     DOMPRINTF_CALLED(dom->xch);
 
+    if ( dom->pvh_enabled )
+    {
+        xc_dom_panic(dom->xch, XC_INTERNAL_ERROR,
+                     "%s: PVH not supported for 32bit guests.", __FUNCTION__);
+        return -1;
+    }
+
     /* clear everything */
     memset(ctxt, 0, sizeof(*ctxt));
 
@@ -629,12 +637,6 @@ static int vcpu_x86_64(struct xc_dom_image *dom, void *ptr)
     /* clear everything */
     memset(ctxt, 0, sizeof(*ctxt));
 
-    ctxt->user_regs.ds = FLAT_KERNEL_DS_X86_64;
-    ctxt->user_regs.es = FLAT_KERNEL_DS_X86_64;
-    ctxt->user_regs.fs = FLAT_KERNEL_DS_X86_64;
-    ctxt->user_regs.gs = FLAT_KERNEL_DS_X86_64;
-    ctxt->user_regs.ss = FLAT_KERNEL_SS_X86_64;
-    ctxt->user_regs.cs = FLAT_KERNEL_CS_X86_64;
     ctxt->user_regs.rip = dom->parms.virt_entry;
     ctxt->user_regs.rsp =
         dom->parms.virt_base + (dom->bootstack_pfn + 1) * PAGE_SIZE_X86;
@@ -642,15 +644,25 @@ static int vcpu_x86_64(struct xc_dom_image *dom, void *ptr)
         dom->parms.virt_base + (dom->start_info_pfn) * PAGE_SIZE_X86;
     ctxt->user_regs.rflags = 1 << 9; /* Interrupt Enable */
 
-    ctxt->kernel_ss = ctxt->user_regs.ss;
-    ctxt->kernel_sp = ctxt->user_regs.esp;
-
     ctxt->flags = VGCF_in_kernel_X86_64 | VGCF_online_X86_64;
     cr3_pfn = xc_dom_p2m_guest(dom, dom->pgtables_seg.pfn);
     ctxt->ctrlreg[3] = xen_pfn_to_cr3_x86_64(cr3_pfn);
     DOMPRINTF("%s: cr3: pfn 0x%" PRIpfn " mfn 0x%" PRIpfn "",
               __FUNCTION__, dom->pgtables_seg.pfn, cr3_pfn);
 
+    if ( dom->pvh_enabled )
+        return 0;
+
+    ctxt->user_regs.ds = FLAT_KERNEL_DS_X86_64;
+    ctxt->user_regs.es = FLAT_KERNEL_DS_X86_64;
+    ctxt->user_regs.fs = FLAT_KERNEL_DS_X86_64;
+    ctxt->user_regs.gs = FLAT_KERNEL_DS_X86_64;
+    ctxt->user_regs.ss = FLAT_KERNEL_SS_X86_64;
+    ctxt->user_regs.cs = FLAT_KERNEL_CS_X86_64;
+
+    ctxt->kernel_ss = ctxt->user_regs.ss;
+    ctxt->kernel_sp = ctxt->user_regs.esp;
+
     return 0;
 }
 
@@ -751,7 +763,7 @@ int arch_setup_meminit(struct xc_dom_image *dom)
     rc = x86_compat(dom->xch, dom->guest_domid, dom->guest_type);
     if ( rc )
         return rc;
-    if ( xc_dom_feature_translated(dom) )
+    if ( xc_dom_feature_translated(dom) && !dom->pvh_enabled )
     {
         dom->shadow_enabled = 1;
         rc = x86_shadow(dom->xch, dom->guest_domid);
@@ -827,6 +839,38 @@ int arch_setup_bootearly(struct xc_dom_image *dom)
     return 0;
 }
 
+/*
+ * Map grant table frames into guest physmap. PVH manages grant during boot
+ * via HVM mechanisms.
+ */
+static int map_grant_table_frames(struct xc_dom_image *dom)
+{
+    int i, rc;
+
+    if ( dom->pvh_enabled )
+        return 0;
+
+    for ( i = 0; ; i++ )
+    {
+        rc = xc_domain_add_to_physmap(dom->xch, dom->guest_domid,
+                                      XENMAPSPACE_grant_table,
+                                      i, dom->total_pages + i);
+        if ( rc != 0 )
+        {
+            if ( (i > 0) && (errno == EINVAL) )
+            {
+                DOMPRINTF("%s: %d grant tables mapped", __FUNCTION__, i);
+                break;
+            }
+            xc_dom_panic(dom->xch, XC_INTERNAL_ERROR,
+                         "%s: mapping grant tables failed " "(pfn=0x%" PRIpfn
+                         ", rc=%d)", __FUNCTION__, dom->total_pages + i, rc);
+            return rc;
+        }
+    }
+    return 0;
+}
+
 int arch_setup_bootlate(struct xc_dom_image *dom)
 {
     static const struct {
@@ -865,7 +909,6 @@ int arch_setup_bootlate(struct xc_dom_image *dom)
     else
     {
         /* paravirtualized guest with auto-translation */
-        int i;
 
         /* Map shared info frame into guest physmap. */
         rc = xc_domain_add_to_physmap(dom->xch, dom->guest_domid,
@@ -879,25 +922,10 @@ int arch_setup_bootlate(struct xc_dom_image *dom)
             return rc;
         }
 
-        /* Map grant table frames into guest physmap. */
-        for ( i = 0; ; i++ )
-        {
-            rc = xc_domain_add_to_physmap(dom->xch, dom->guest_domid,
-                                          XENMAPSPACE_grant_table,
-                                          i, dom->total_pages + i);
-            if ( rc != 0 )
-            {
-                if ( (i > 0) && (errno == EINVAL) )
-                {
-                    DOMPRINTF("%s: %d grant tables mapped", __FUNCTION__, i);
-                    break;
-                }
-                xc_dom_panic(dom->xch, XC_INTERNAL_ERROR,
-                             "%s: mapping grant tables failed " "(pfn=0x%"
-                             PRIpfn ", rc=%d)", __FUNCTION__, dom->total_pages + i, rc);
-                return rc;
-            }
-        }
+        rc = map_grant_table_frames(dom);
+        if ( rc != 0 )
+            return rc;
+
         shinfo = dom->shared_info_pfn;
     }
 
-- 
1.7.2.3

[V3 PATCH 3/3] PVH xen tools: libxl changes to create a PVH guest.

[Mukesh Rathor]

Signed-off-by: Mukesh Rathor <mukesh.rathor@oracle.com>
Acked-by: Ian Campbell <ian.campbell@citrix.com>
------
V2: set c_info->hap to default value of pvh, and use LOG(ERROR...).
    Move PVH check to xc_dom_gnttab_init.
    Move xl doc change here.
---
 docs/man/xl.cfg.pod.5        |    3 +++
 tools/libxl/libxl.h          |    6 ++++++
 tools/libxl/libxl_create.c   |   12 ++++++++++++
 tools/libxl/libxl_dom.c      |    2 ++
 tools/libxl/libxl_internal.h |    1 +
 tools/libxl/libxl_types.idl  |    1 +
 tools/libxl/libxl_x86.c      |    4 +++-
 tools/libxl/xl_cmdimpl.c     |    1 +
 8 files changed, 29 insertions(+), 1 deletions(-)

diff --git a/docs/man/xl.cfg.pod.5 b/docs/man/xl.cfg.pod.5
index 08d6cc4..65d69f8 100644
--- a/docs/man/xl.cfg.pod.5
+++ b/docs/man/xl.cfg.pod.5
@@ -634,6 +634,9 @@ if your particular guest kernel does not require this behaviour then
 it is safe to allow this to be enabled but you may wish to disable it
 anyway.
 
+=item B<pvh=BOOLEAN>
+Selects whether to run this PV guest in an HVM container. Default is 0.
+
 =back
 
 =head2 Fully-virtualised (HVM) Guest Specific Options
diff --git a/tools/libxl/libxl.h b/tools/libxl/libxl.h
index be19bf5..f0b0701 100644
--- a/tools/libxl/libxl.h
+++ b/tools/libxl/libxl.h
@@ -344,6 +344,12 @@
  */
 #define LIBXL_HAVE_DOMINFO_OUTSTANDING_MEMKB 1
 
+/*
+ * LIBXL_HAVE_CREATEINFO_PVH
+ * If this is defined, then libxl supports creation of a PVH guest.
+ */
+#define LIBXL_HAVE_CREATEINFO_PVH 1
+
 /* Functions annotated with LIBXL_EXTERNAL_CALLERS_ONLY may not be
  * called from within libxl itself. Callers outside libxl, who
  * do not #include libxl_internal.h, are fine. */
diff --git a/tools/libxl/libxl_create.c b/tools/libxl/libxl_create.c
index 0c32d0b..6d2101e 100644
--- a/tools/libxl/libxl_create.c
+++ b/tools/libxl/libxl_create.c
@@ -33,6 +33,9 @@ int libxl__domain_create_info_setdefault(libxl__gc *gc,
     if (c_info->type == LIBXL_DOMAIN_TYPE_HVM) {
         libxl_defbool_setdefault(&c_info->hap, true);
         libxl_defbool_setdefault(&c_info->oos, true);
+    } else {
+        libxl_defbool_setdefault(&c_info->pvh, false);
+        libxl_defbool_setdefault(&c_info->hap, libxl_defbool_val(c_info->pvh));
     }
 
     libxl_defbool_setdefault(&c_info->run_hotplug_scripts, true);
@@ -346,6 +349,8 @@ int libxl__domain_build(libxl__gc *gc,
 
         break;
     case LIBXL_DOMAIN_TYPE_PV:
+        state->pvh_enabled = libxl_defbool_val(d_config->c_info.pvh);
+
         ret = libxl__build_pv(gc, domid, info, state);
         if (ret)
             goto out;
@@ -405,6 +410,13 @@ int libxl__domain_make(libxl__gc *gc, libxl_domain_create_info *info,
         flags |= XEN_DOMCTL_CDF_hvm_guest;
         flags |= libxl_defbool_val(info->hap) ? XEN_DOMCTL_CDF_hap : 0;
         flags |= libxl_defbool_val(info->oos) ? 0 : XEN_DOMCTL_CDF_oos_off;
+    } else if ( libxl_defbool_val(info->pvh) ) {
+        if ( !libxl_defbool_val(info->hap) ) {
+            LOG(ERROR, "HAP must be on for PVH");
+            rc = ERROR_INVAL;
+            goto out;
+        }
+        flags |= XEN_DOMCTL_CDF_hap;
     }
     *domid = -1;
 
diff --git a/tools/libxl/libxl_dom.c b/tools/libxl/libxl_dom.c
index 6e2252a..89e919e 100644
--- a/tools/libxl/libxl_dom.c
+++ b/tools/libxl/libxl_dom.c
@@ -338,6 +338,8 @@ int libxl__build_pv(libxl__gc *gc, uint32_t domid,
         return ERROR_FAIL;
     }
 
+    dom->pvh_enabled = state->pvh_enabled;
+
     LOG(DEBUG, "pv kernel mapped %d path %s\n", state->pv_kernel.mapped, state->pv_kernel.path);
     if (state->pv_kernel.mapped) {
         ret = xc_dom_kernel_mem(dom,
diff --git a/tools/libxl/libxl_internal.h b/tools/libxl/libxl_internal.h
index f051d91..441ec66 100644
--- a/tools/libxl/libxl_internal.h
+++ b/tools/libxl/libxl_internal.h
@@ -886,6 +886,7 @@ typedef struct {
     libxl__file_reference pv_kernel;
     libxl__file_reference pv_ramdisk;
     const char * pv_cmdline;
+    bool pvh_enabled;
 } libxl__domain_build_state;
 
 _hidden int libxl__build_pre(libxl__gc *gc, uint32_t domid,
diff --git a/tools/libxl/libxl_types.idl b/tools/libxl/libxl_types.idl
index 85341a0..9919786 100644
--- a/tools/libxl/libxl_types.idl
+++ b/tools/libxl/libxl_types.idl
@@ -248,6 +248,7 @@ libxl_domain_create_info = Struct("domain_create_info",[
     ("platformdata", libxl_key_value_list),
     ("poolid",       uint32),
     ("run_hotplug_scripts",libxl_defbool),
+    ("pvh",          libxl_defbool),
     ], dir=DIR_IN)
 
 MemKB = UInt(64, init_val = "LIBXL_MEMKB_DEFAULT")
diff --git a/tools/libxl/libxl_x86.c b/tools/libxl/libxl_x86.c
index a78c91d..87a8110 100644
--- a/tools/libxl/libxl_x86.c
+++ b/tools/libxl/libxl_x86.c
@@ -290,7 +290,9 @@ int libxl__arch_domain_create(libxl__gc *gc, libxl_domain_config *d_config,
     if (rtc_timeoffset)
         xc_domain_set_time_offset(ctx->xch, domid, rtc_timeoffset);
 
-    if (d_config->b_info.type == LIBXL_DOMAIN_TYPE_HVM) {
+    if (d_config->b_info.type == LIBXL_DOMAIN_TYPE_HVM ||
+        libxl_defbool_val(d_config->c_info.pvh)) {
+
         unsigned long shadow;
         shadow = (d_config->b_info.shadow_memkb + 1023) / 1024;
         xc_shadow_control(ctx->xch, domid, XEN_DOMCTL_SHADOW_OP_SET_ALLOCATION, NULL, 0, &shadow, 0, NULL);
diff --git a/tools/libxl/xl_cmdimpl.c b/tools/libxl/xl_cmdimpl.c
index 884f050..2ee68a9 100644
--- a/tools/libxl/xl_cmdimpl.c
+++ b/tools/libxl/xl_cmdimpl.c
@@ -610,6 +610,7 @@ static void parse_config_data(const char *config_source,
         !strncmp(buf, "hvm", strlen(buf)))
         c_info->type = LIBXL_DOMAIN_TYPE_HVM;
 
+    xlu_cfg_get_defbool(config, "pvh", &c_info->pvh, 0);
     xlu_cfg_get_defbool(config, "hap", &c_info->hap, 0);
 
     if (xlu_cfg_replace_string (config, "name", &c_info->name, 0)) {
-- 
1.7.2.3

Re: [V3 PATCH 1/3] PVH xen tools: In Elf code, check hvm callback vector

[Jan Beulich]

>>> On 10.09.13 at 23:55, Mukesh Rathor <mukesh.rathor@oracle.com> wrote:

The patch went in yesterday, no need resending.

Jan

Re: [V3 PATCH 2/3] PVH xen tools: libxc changes to build a PVH guest.

[Ian Campbell]

On Tue, 2013-09-10 at 14:55 -0700, Mukesh Rathor wrote:
> Signed-off-by: Mukesh Rathor <mukesh.rathor@oracle.com>
> -----

This needs to be exactly the "---" I quoted when I asked for it in order
to be affective (it causes git am to strip these comments)

> V2: Make pvh_features string const, and fail 32bit PVH guest creation.
>     Move PVH check to xc_dom_gnttab_init().
> V3: let xc_dom_gnttab_hvm_seed be called for PVH.
> ---

 ^ Like this

>  tools/libxc/xc_dom.h      |    1 +
>  tools/libxc/xc_dom_core.c |    9 ++++
>  tools/libxc/xc_dom_x86.c  |   90 +++++++++++++++++++++++++++++---------------
>  3 files changed, 69 insertions(+), 31 deletions(-)
> diff --git a/tools/libxc/xc_dom_core.c b/tools/libxc/xc_dom_core.c
> index 0f367f6..faa7e0f 100644
> --- a/tools/libxc/xc_dom_core.c
> +++ b/tools/libxc/xc_dom_core.c
> @@ -766,6 +766,15 @@ int xc_dom_parse_image(struct xc_dom_image *dom)
>          goto err;
>      }
>  
> +    if ( dom->pvh_enabled )
> +    {
> +        const char *pvh_features = "writable_descriptor_tables|"
> +                                   "auto_translated_physmap|"
> +                                   "supervisor_mode_kernel|"
> +                                   "hvm_callback_vector";
> +        elf_xen_parse_features(pvh_features, dom->f_requested, NULL);

Is there a check somewhere that these features actually ended up being
available?

> +    }
> +
>      /* check features */
>      for ( i = 0; i < XENFEAT_NR_SUBMAPS; i++ )
>      {

Re: [V3 PATCH 2/3] PVH xen tools: libxc changes to build a PVH guest.

[Mukesh Rathor]

On Wed, 11 Sep 2013 11:03:45 +0100
Ian Campbell <Ian.Campbell@citrix.com> wrote:

> On Tue, 2013-09-10 at 14:55 -0700, Mukesh Rathor wrote:
> > Signed-off-by: Mukesh Rathor <mukesh.rathor@oracle.com>
> > -----
> 
> This needs to be exactly the "---" I quoted when I asked for it in
> order to be affective (it causes git am to strip these comments)
> 
> > V2: Make pvh_features string const, and fail 32bit PVH guest
> > creation. Move PVH check to xc_dom_gnttab_init().
> > V3: let xc_dom_gnttab_hvm_seed be called for PVH.
> > ---
> 
>  ^ Like this
> 
> >  tools/libxc/xc_dom.h      |    1 +
> >  tools/libxc/xc_dom_core.c |    9 ++++
> >  tools/libxc/xc_dom_x86.c  |   90
> > +++++++++++++++++++++++++++++--------------- 3 files changed, 69
> > insertions(+), 31 deletions(-) diff --git
> > a/tools/libxc/xc_dom_core.c b/tools/libxc/xc_dom_core.c index
> > 0f367f6..faa7e0f 100644 --- a/tools/libxc/xc_dom_core.c
> > +++ b/tools/libxc/xc_dom_core.c
> > @@ -766,6 +766,15 @@ int xc_dom_parse_image(struct xc_dom_image
> > *dom) goto err;
> >      }
> >  
> > +    if ( dom->pvh_enabled )
> > +    {
> > +        const char *pvh_features = "writable_descriptor_tables|"
> > +                                   "auto_translated_physmap|"
> > +                                   "supervisor_mode_kernel|"
> > +                                   "hvm_callback_vector";
> > +        elf_xen_parse_features(pvh_features, dom->f_requested,
> > NULL);
> 
> Is there a check somewhere that these features actually ended up being
> available?

Right below it will check to make sure active features are supported.

thanks
mukesh

Re: [V3 PATCH 2/3] PVH xen tools: libxc changes to build a PVH guest.

[Ian Campbell]

On Wed, 2013-09-11 at 14:41 -0700, Mukesh Rathor wrote:
> On Wed, 11 Sep 2013 11:03:45 +0100
> Ian Campbell <Ian.Campbell@citrix.com> wrote:
> 
> > On Tue, 2013-09-10 at 14:55 -0700, Mukesh Rathor wrote:
> > > Signed-off-by: Mukesh Rathor <mukesh.rathor@oracle.com>
> > > -----
> > 
> > This needs to be exactly the "---" I quoted when I asked for it in
> > order to be affective (it causes git am to strip these comments)
> > 
> > > V2: Make pvh_features string const, and fail 32bit PVH guest
> > > creation. Move PVH check to xc_dom_gnttab_init().
> > > V3: let xc_dom_gnttab_hvm_seed be called for PVH.
> > > ---
> > 
> >  ^ Like this
> > 
> > >  tools/libxc/xc_dom.h      |    1 +
> > >  tools/libxc/xc_dom_core.c |    9 ++++
> > >  tools/libxc/xc_dom_x86.c  |   90
> > > +++++++++++++++++++++++++++++--------------- 3 files changed, 69
> > > insertions(+), 31 deletions(-) diff --git
> > > a/tools/libxc/xc_dom_core.c b/tools/libxc/xc_dom_core.c index
> > > 0f367f6..faa7e0f 100644 --- a/tools/libxc/xc_dom_core.c
> > > +++ b/tools/libxc/xc_dom_core.c
> > > @@ -766,6 +766,15 @@ int xc_dom_parse_image(struct xc_dom_image
> > > *dom) goto err;
> > >      }
> > >  
> > > +    if ( dom->pvh_enabled )
> > > +    {
> > > +        const char *pvh_features = "writable_descriptor_tables|"
> > > +                                   "auto_translated_physmap|"
> > > +                                   "supervisor_mode_kernel|"
> > > +                                   "hvm_callback_vector";
> > > +        elf_xen_parse_features(pvh_features, dom->f_requested,
> > > NULL);
> > 
> > Is there a check somewhere that these features actually ended up being
> > available?
> 
> Right below it will check to make sure active features are supported.

Of course, sorry -- I was confused what parse features was filling in.

I'll reply to v4 with my ack.

Ian.