xen: report PV capability in sysctl and use it in toolstack

0e2c886ef ("xen: decouple HVM and IOMMU capabilities") provided a
truth table for what `xl info` would report. In order to make the
table work xen will need to report its PV capability.

Replace cap_directio with cap_pv in libxl IDL. It is safe to do so
because cap_directio has never been released. Revert to use
cap_hvm_directio to mark the availability of IOMMU, to save us from
providing a compatibility layer.

Don't bump sysctl version number because we've already done so.

Also provide a new virt_caps "pv", change "directio" to "pv_directio".
The truth table is now:

    pv      hvm     iommu           flags in xl info
    0       0       x               n/a
    0       1       0               hvm
    0       1       1               hvm hvm_directio
    1       0       0               pv
    1       0       1               pv pv_directio
    1       1       0               pv hvm
    1       1       1               pv hvm hvm_directio pv_directio

Signed-off-by: Wei Liu <wei.liu2@citrix.com>
Acked-by: Andrew Cooper <andrew.cooper3@citrix.com>
Acked-by: Ian Jackson <ian.jackson@eu.citrix.com>

tools/libxl/libxl.c

@@ -396,9 +396,9 @@ int libxl_get_physinfo(libxl_ctx *ctx, libxl_physinfo *physinfo)
     memcpy(physinfo->hw_cap,xcphysinfo.hw_cap, sizeof(physinfo->hw_cap));
 
     physinfo->cap_hvm = !!(xcphysinfo.capabilities & XEN_SYSCTL_PHYSCAP_hvm);
-    physinfo->cap_directio =
+    physinfo->cap_pv = !!(xcphysinfo.capabilities & XEN_SYSCTL_PHYSCAP_pv);
+    physinfo->cap_hvm_directio =
         !!(xcphysinfo.capabilities & XEN_SYSCTL_PHYSCAP_directio);
-    physinfo->cap_hvm_directio = physinfo->cap_hvm && physinfo->cap_directio;
 
     GC_FREE;
     return 0;

tools/libxl/libxl.h

@@ -67,11 +67,11 @@
  * the same $(XEN_VERSION) (e.g. throughout a major release).
  */
 
-/* LIBXL_HAVE_PHYSINFO_CAP_DIRECTIO
+/* LIBXL_HAVE_PHYSINFO_CAP_PV
  *
- * If this is defined, libxl_physinfo has a "cap_directio" field.
+ * If this is defined, libxl_physinfo has a "cap_pv" field.
  */
-#define LIBXL_HAVE_PHYSINFO_CAP_DIRECTIO 1
+#define LIBXL_HAVE_PHYSINFO_CAP_PV 1
 
 /* LIBXL_HAVE_CONSOLE_NOTIFY_FD
  *

tools/libxl/libxl_types.idl

@@ -1013,8 +1013,8 @@ libxl_physinfo = Struct("physinfo", [
     ("hw_cap", libxl_hwcap),
 
     ("cap_hvm", bool),
-    ("cap_hvm_directio", bool),
-    ("cap_directio", bool),
+    ("cap_pv", bool),
+    ("cap_hvm_directio", bool), # No longer HVM specific
     ], dir=DIR_OUT)
 
 libxl_connectorinfo = Struct("connectorinfo", [

tools/xl/xl_info.c

@@ -210,10 +210,11 @@ static void output_physinfo(void)
          info.hw_cap[4], info.hw_cap[5], info.hw_cap[6], info.hw_cap[7]
         );
 
-    maybe_printf("virt_caps              :%s%s%s\n",
+    maybe_printf("virt_caps              :%s%s%s%s\n",
+         info.cap_pv ? " pv" : "",
          info.cap_hvm ? " hvm" : "",
-         info.cap_hvm_directio ? " hvm_directio" : "",
-         info.cap_directio ? " directio" : ""
+         info.cap_hvm && info.cap_hvm_directio ? " hvm_directio" : "",
+         info.cap_pv && info.cap_hvm_directio ? " pv_directio" : ""
         );
 
     vinfo = libxl_get_version_info(ctx);

xen/arch/x86/sysctl.c

@@ -120,6 +120,8 @@ void arch_do_physinfo(struct xen_sysctl_physinfo *pi)
            min(sizeof(pi->hw_cap), sizeof(boot_cpu_data.x86_capability)));
     if ( hvm_enabled )
         pi->capabilities |= XEN_SYSCTL_PHYSCAP_hvm;
+    if ( IS_ENABLED(CONFIG_PV) )
+        pi->capabilities |= XEN_SYSCTL_PHYSCAP_pv;
     if ( iommu_enabled )
         pi->capabilities |= XEN_SYSCTL_PHYSCAP_directio;
 }

xen/include/public/sysctl.h

@@ -85,8 +85,11 @@ struct xen_sysctl_tbuf_op {
  /* (x86) The platform supports HVM guests. */
 #define _XEN_SYSCTL_PHYSCAP_hvm          0
 #define XEN_SYSCTL_PHYSCAP_hvm           (1u<<_XEN_SYSCTL_PHYSCAP_hvm)
+ /* (x86) The platform supports PV guests. */
+#define _XEN_SYSCTL_PHYSCAP_pv           1
+#define XEN_SYSCTL_PHYSCAP_pv            (1u<<_XEN_SYSCTL_PHYSCAP_pv)
  /* (x86) The platform supports direct access to I/O devices with IOMMU. */
-#define _XEN_SYSCTL_PHYSCAP_directio 1
+#define _XEN_SYSCTL_PHYSCAP_directio     2
 #define XEN_SYSCTL_PHYSCAP_directio  (1u<<_XEN_SYSCTL_PHYSCAP_directio)
 struct xen_sysctl_physinfo {
     uint32_t threads_per_core;