[PATCH v2 23/30] xen+tools: Export maximum host and guest cpu featuresets via SYSCTL

[Andrew Cooper <andrew.cooper3@citrix.com>]

And provide stubs for toolstack use.

Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
---
CC: Jan Beulich <JBeulich@suse.com>
CC: Tim Deegan <tim@xen.org>
CC: Ian Campbell <Ian.Campbell@citrix.com>
CC: Wei Liu <wei.liu2@citrix.com>
CC: David Scott <dave@recoil.org>
CC: Rob Hoes <Rob.Hoes@citrix.com>

v2:
 * Rebased to use libxencall
 * Improve hypercall documentation
---
 tools/libxc/include/xenctrl.h       |  3 ++
 tools/libxc/xc_cpuid_x86.c          | 27 +++++++++++++++
 tools/ocaml/libs/xc/xenctrl.ml      |  3 ++
 tools/ocaml/libs/xc/xenctrl.mli     |  4 +++
 tools/ocaml/libs/xc/xenctrl_stubs.c | 35 ++++++++++++++++++++
 xen/arch/x86/sysctl.c               | 66 +++++++++++++++++++++++++++++++++++++
 xen/include/public/sysctl.h         | 25 ++++++++++++++
 7 files changed, 163 insertions(+)

diff --git a/tools/libxc/include/xenctrl.h b/tools/libxc/include/xenctrl.h
index 1a5f4ec..5a7500a 100644
--- a/tools/libxc/include/xenctrl.h
+++ b/tools/libxc/include/xenctrl.h
@@ -2571,6 +2571,9 @@ int xc_psr_cat_get_domain_data(xc_interface *xch, uint32_t domid,
 int xc_psr_cat_get_l3_info(xc_interface *xch, uint32_t socket,
                            uint32_t *cos_max, uint32_t *cbm_len,
                            bool *cdp_enabled);
+
+int xc_get_cpu_featureset(xc_interface *xch, uint32_t index,
+                          uint32_t *nr_features, uint32_t *featureset);
 #endif
 
 /* Compat shims */
diff --git a/tools/libxc/xc_cpuid_x86.c b/tools/libxc/xc_cpuid_x86.c
index c142595..7b802da 100644
--- a/tools/libxc/xc_cpuid_x86.c
+++ b/tools/libxc/xc_cpuid_x86.c
@@ -33,6 +33,33 @@
 #define DEF_MAX_INTELEXT  0x80000008u
 #define DEF_MAX_AMDEXT    0x8000001cu
 
+int xc_get_cpu_featureset(xc_interface *xch, uint32_t index,
+                          uint32_t *nr_features, uint32_t *featureset)
+{
+    DECLARE_SYSCTL;
+    DECLARE_HYPERCALL_BOUNCE(featureset,
+                             *nr_features * sizeof(*featureset),
+                             XC_HYPERCALL_BUFFER_BOUNCE_OUT);
+    int ret;
+
+    if ( xc_hypercall_bounce_pre(xch, featureset) )
+        return -1;
+
+    sysctl.cmd = XEN_SYSCTL_get_cpu_featureset;
+    sysctl.u.cpu_featureset.index = index;
+    sysctl.u.cpu_featureset.nr_features = *nr_features;
+    set_xen_guest_handle(sysctl.u.cpu_featureset.features, featureset);
+
+    ret = do_sysctl(xch, &sysctl);
+
+    xc_hypercall_bounce_post(xch, featureset);
+
+    if ( !ret )
+        *nr_features = sysctl.u.cpu_featureset.nr_features;
+
+    return ret;
+}
+
 struct cpuid_domain_info
 {
     enum
diff --git a/tools/ocaml/libs/xc/xenctrl.ml b/tools/ocaml/libs/xc/xenctrl.ml
index 58a53a1..75006e7 100644
--- a/tools/ocaml/libs/xc/xenctrl.ml
+++ b/tools/ocaml/libs/xc/xenctrl.ml
@@ -242,6 +242,9 @@ external version_changeset: handle -> string = "stub_xc_version_changeset"
 external version_capabilities: handle -> string =
   "stub_xc_version_capabilities"
 
+type featureset_index = Featureset_raw | Featureset_host | Featureset_pv | Featureset_hvm
+external get_cpu_featureset : handle -> featureset_index -> int64 array = "stub_xc_get_cpu_featureset"
+
 external watchdog : handle -> int -> int32 -> int
   = "stub_xc_watchdog"
 
diff --git a/tools/ocaml/libs/xc/xenctrl.mli b/tools/ocaml/libs/xc/xenctrl.mli
index 16443df..720e4b2 100644
--- a/tools/ocaml/libs/xc/xenctrl.mli
+++ b/tools/ocaml/libs/xc/xenctrl.mli
@@ -147,6 +147,10 @@ external version_compile_info : handle -> compile_info
 external version_changeset : handle -> string = "stub_xc_version_changeset"
 external version_capabilities : handle -> string
   = "stub_xc_version_capabilities"
+
+type featureset_index = Featureset_raw | Featureset_host | Featureset_pv | Featureset_hvm
+external get_cpu_featureset : handle -> featureset_index -> int64 array = "stub_xc_get_cpu_featureset"
+
 type core_magic = Magic_hvm | Magic_pv
 type core_header = {
   xch_magic : core_magic;
diff --git a/tools/ocaml/libs/xc/xenctrl_stubs.c b/tools/ocaml/libs/xc/xenctrl_stubs.c
index 74928e9..e7adf37 100644
--- a/tools/ocaml/libs/xc/xenctrl_stubs.c
+++ b/tools/ocaml/libs/xc/xenctrl_stubs.c
@@ -1214,6 +1214,41 @@ CAMLprim value stub_xc_domain_deassign_device(value xch, value domid, value desc
 	CAMLreturn(Val_unit);
 }
 
+CAMLprim value stub_xc_get_cpu_featureset(value xch, value idx)
+{
+	CAMLparam2(xch, idx);
+	CAMLlocal1(bitmap_val);
+
+	/* Safe, because of the global ocaml lock. */
+	static uint32_t fs_len;
+
+	if (fs_len == 0)
+	{
+		int ret = xc_get_cpu_featureset(_H(xch), 0, &fs_len, NULL);
+
+		if (ret || (fs_len == 0))
+			failwith_xc(_H(xch));
+	}
+
+	{
+		/* To/from hypervisor to retrieve actual featureset */
+		uint32_t fs[fs_len], len = fs_len;
+		unsigned int i;
+
+		int ret = xc_get_cpu_featureset(_H(xch), Int_val(idx), &len, fs);
+
+		if (ret)
+			failwith_xc(_H(xch));
+
+		bitmap_val = caml_alloc(len, 0);
+
+		for (i = 0; i < len; ++i)
+			Store_field(bitmap_val, i, caml_copy_int64(fs[i]));
+	}
+
+	CAMLreturn(bitmap_val);
+}
+
 CAMLprim value stub_xc_watchdog(value xch, value domid, value timeout)
 {
 	CAMLparam3(xch, domid, timeout);
diff --git a/xen/arch/x86/sysctl.c b/xen/arch/x86/sysctl.c
index 58cbd70..837a307 100644
--- a/xen/arch/x86/sysctl.c
+++ b/xen/arch/x86/sysctl.c
@@ -30,6 +30,7 @@
 #include <xen/cpu.h>
 #include <xsm/xsm.h>
 #include <asm/psr.h>
+#include <asm/cpuid.h>
 
 struct l3_cache_info {
     int ret;
@@ -190,6 +191,71 @@ long arch_do_sysctl(
         }
         break;
 
+    case XEN_SYSCTL_get_cpu_featureset:
+    {
+        const uint32_t *featureset;
+        unsigned int nr;
+
+        /* Request for maximum number of features? */
+        if ( guest_handle_is_null(sysctl->u.cpu_featureset.features) )
+        {
+            sysctl->u.cpu_featureset.nr_features = FSCAPINTS;
+            if ( __copy_field_to_guest(u_sysctl, sysctl,
+                                       u.cpu_featureset.nr_features) )
+                ret = -EFAULT;
+            break;
+        }
+
+        /* Clip the number of entries. */
+        nr = sysctl->u.cpu_featureset.nr_features;
+        if ( nr > FSCAPINTS )
+            nr = FSCAPINTS;
+
+        switch ( sysctl->u.cpu_featureset.index )
+        {
+        case XEN_SYSCTL_cpu_featureset_raw:
+            featureset = raw_featureset;
+            break;
+
+        case XEN_SYSCTL_cpu_featureset_host:
+            featureset = host_featureset;
+            break;
+
+        case XEN_SYSCTL_cpu_featureset_pv:
+            featureset = pv_featureset;
+            break;
+
+        case XEN_SYSCTL_cpu_featureset_hvm:
+            featureset = hvm_featureset;
+            break;
+
+        default:
+            featureset = NULL;
+            break;
+        }
+
+        /* Bad featureset index? */
+        if ( !ret && !featureset )
+            ret = -EINVAL;
+
+        /* Copy the requested featureset into place. */
+        if ( !ret && copy_to_guest(sysctl->u.cpu_featureset.features,
+                                   featureset, nr) )
+            ret = -EFAULT;
+
+        /* Inform the caller of how many features we wrote. */
+        sysctl->u.cpu_featureset.nr_features = nr;
+        if ( !ret && __copy_field_to_guest(u_sysctl, sysctl,
+                                           u.cpu_featureset.nr_features) )
+            ret = -EFAULT;
+
+        /* Inform the caller if there was more data to provide. */
+        if ( !ret && nr < FSCAPINTS )
+            ret = -ENOBUFS;
+
+        break;
+    }
+
     default:
         ret = -ENOSYS;
         break;
diff --git a/xen/include/public/sysctl.h b/xen/include/public/sysctl.h
index 96680eb..434cb2d 100644
--- a/xen/include/public/sysctl.h
+++ b/xen/include/public/sysctl.h
@@ -766,6 +766,29 @@ struct xen_sysctl_tmem_op {
 typedef struct xen_sysctl_tmem_op xen_sysctl_tmem_op_t;
 DEFINE_XEN_GUEST_HANDLE(xen_sysctl_tmem_op_t);
 
+/*
+ * XEN_SYSCTL_get_cpu_featureset (x86 specific)
+ *
+ * Return information about the maximum sets of features which can be offered
+ * to different types of guests.  This is all strictly information as found in
+ * `cpuid` feature leaves with no synthetic additions.
+ */
+struct xen_sysctl_cpu_featureset {
+#define XEN_SYSCTL_cpu_featureset_raw      0
+#define XEN_SYSCTL_cpu_featureset_host     1
+#define XEN_SYSCTL_cpu_featureset_pv       2
+#define XEN_SYSCTL_cpu_featureset_hvm      3
+    uint32_t index;       /* IN: Which featureset to query? */
+    uint32_t nr_features; /* IN/OUT: Number of entries in/written to
+                           * 'features', or the maximum number of features if
+                           * the guest handle is NULL.  NB. All featuresets
+                           * come from the same numberspace, so have the same
+                           * maximum length. */
+    XEN_GUEST_HANDLE_64(uint32) features; /* OUT: */
+};
+typedef struct xen_sysctl_featureset xen_sysctl_featureset_t;
+DEFINE_XEN_GUEST_HANDLE(xen_sysctl_featureset_t);
+
 struct xen_sysctl {
     uint32_t cmd;
 #define XEN_SYSCTL_readconsole                    1
@@ -791,6 +814,7 @@ struct xen_sysctl {
 #define XEN_SYSCTL_pcitopoinfo                   22
 #define XEN_SYSCTL_psr_cat_op                    23
 #define XEN_SYSCTL_tmem_op                       24
+#define XEN_SYSCTL_get_cpu_featureset            25
     uint32_t interface_version; /* XEN_SYSCTL_INTERFACE_VERSION */
     union {
         struct xen_sysctl_readconsole       readconsole;
@@ -816,6 +840,7 @@ struct xen_sysctl {
         struct xen_sysctl_psr_cmt_op        psr_cmt_op;
         struct xen_sysctl_psr_cat_op        psr_cat_op;
         struct xen_sysctl_tmem_op           tmem_op;
+        struct xen_sysctl_cpu_featureset    cpu_featureset;
         uint8_t                             pad[128];
     } u;
 };
-- 
2.1.4