[Xen-devel] [PATCH v9 3/6] sysctl / libxl: report whether IOMMU/HAP page table sharing is supported

[Paul Durrant <paul.durrant@xxxxxxxxxx>]

This patch defines a new bit reported in the hw_cap field of struct
xen_sysctl_physinfo to indicate whether the platform supports sharing of
HAP page tables (i.e. the P2M) with the IOMMU. This informs the toolstack
whether the domain needs extra memory to store discrete IOMMU page tables
or not.

Signed-off-by: Paul Durrant <paul.durrant@xxxxxxxxxx>
---
Cc: Ian Jackson <ian.jackson@xxxxxxxxxxxxx>
Cc: Wei Liu <wl@xxxxxxx>
Cc: Anthony PERARD <anthony.perard@xxxxxxxxxx>
Cc: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
Cc: George Dunlap <George.Dunlap@xxxxxxxxxxxxx>
Cc: Jan Beulich <jbeulich@xxxxxxxx>
Cc: Julien Grall <julien.grall@xxxxxxx>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
Cc: Stefano Stabellini <sstabellini@xxxxxxxxxx>
Cc: Tim Deegan <tim@xxxxxxx>
Cc: Christian Lindig <christian.lindig@xxxxxxxxxx>
Cc: David Scott <dave@xxxxxxxxxx>

v9:
 - New in v9
---
 tools/libxl/libxl.c             | 2 ++
 tools/libxl/libxl.h             | 7 +++++++
 tools/libxl/libxl_types.idl     | 1 +
 tools/ocaml/libs/xc/xenctrl.ml  | 1 +
 tools/ocaml/libs/xc/xenctrl.mli | 2 +-
 tools/xl/xl_info.c              | 5 +++--
 xen/arch/arm/sysctl.c           | 3 +++
 xen/arch/x86/sysctl.c           | 5 +++++
 xen/include/public/sysctl.h     | 6 +++++-
 9 files changed, 28 insertions(+), 4 deletions(-)

diff --git a/tools/libxl/libxl.c b/tools/libxl/libxl.c
index 5c0fcf320e..dd468eb18e 100644
--- a/tools/libxl/libxl.c
+++ b/tools/libxl/libxl.c
@@ -400,6 +400,8 @@ int libxl_get_physinfo(libxl_ctx *ctx, libxl_physinfo 
*physinfo)
     physinfo->cap_hvm_directio =
         !!(xcphysinfo.capabilities & XEN_SYSCTL_PHYSCAP_directio);
     physinfo->cap_hap = !!(xcphysinfo.capabilities & XEN_SYSCTL_PHYSCAP_hap);
+    physinfo->cap_iommu_hap_pt_share =
+        !!(xcphysinfo.capabilities & XEN_SYSCTL_PHYSCAP_iommu_hap_pt_share);
 
     GC_FREE;
     return 0;
diff --git a/tools/libxl/libxl.h b/tools/libxl/libxl.h
index 3ff67792a7..670a282c5a 100644
--- a/tools/libxl/libxl.h
+++ b/tools/libxl/libxl.h
@@ -401,6 +401,13 @@
  */
 #define LIBXL_HAVE_PHYSINFO_CAP_HAP 1
 
+/*
+ * LIBXL_HAVE_PHYSINFO_CAP_IOMMU_HAP_PT_SHARE indicates that libxl_physinfo
+ * has a cap_iommu_hap_pt_share field that indicates whether the hardware
+ * supports sharing the IOMMU and HAP page tables.
+ */
+#define LIBXL_HAVE_PHYSINFO_CAP_IOMMU_HAP_PT_SHARE 1
+
 /*
  * libxl ABI compatibility
  *
diff --git a/tools/libxl/libxl_types.idl b/tools/libxl/libxl_types.idl
index 9e1f8515d3..bd427def1a 100644
--- a/tools/libxl/libxl_types.idl
+++ b/tools/libxl/libxl_types.idl
@@ -1026,6 +1026,7 @@ libxl_physinfo = Struct("physinfo", [
     ("cap_pv", bool),
     ("cap_hvm_directio", bool), # No longer HVM specific
     ("cap_hap", bool),
+    ("cap_iommu_hap_pt_share", bool),
     ], dir=DIR_OUT)
 
 libxl_connectorinfo = Struct("connectorinfo", [
diff --git a/tools/ocaml/libs/xc/xenctrl.ml b/tools/ocaml/libs/xc/xenctrl.ml
index eaf009f0f9..30da6ba370 100644
--- a/tools/ocaml/libs/xc/xenctrl.ml
+++ b/tools/ocaml/libs/xc/xenctrl.ml
@@ -109,6 +109,7 @@ type physinfo_cap_flag =
        | CAP_PV
        | CAP_DirectIO
        | CAP_HAP
+       | CAP_IOMMU_HAP_PT_SHARE
 
 type physinfo =
 {
diff --git a/tools/ocaml/libs/xc/xenctrl.mli b/tools/ocaml/libs/xc/xenctrl.mli
index e0636de23a..64c35418e8 100644
--- a/tools/ocaml/libs/xc/xenctrl.mli
+++ b/tools/ocaml/libs/xc/xenctrl.mli
@@ -57,7 +57,6 @@ type domain_create_flag =
   | CDF_OOS_OFF
   | CDF_XS_DOMAIN
   | CDF_IOMMU
-
 type domctl_create_config = {
   ssidref: int32;
   handle: string;
@@ -94,6 +93,7 @@ type physinfo_cap_flag =
   | CAP_PV
   | CAP_DirectIO
   | CAP_HAP
+  | CAP_IOMMU_HAP_PT_SHARE
 type physinfo = {
   threads_per_core : int;
   cores_per_socket : int;
diff --git a/tools/xl/xl_info.c b/tools/xl/xl_info.c
index aa6724bc7f..94da5ec91e 100644
--- a/tools/xl/xl_info.c
+++ b/tools/xl/xl_info.c
@@ -210,12 +210,13 @@ 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%s%s\n",
+    maybe_printf("virt_caps              :%s%s%s%s%s%s\n",
          info.cap_pv ? " pv" : "",
          info.cap_hvm ? " hvm" : "",
          info.cap_hvm && info.cap_hvm_directio ? " hvm_directio" : "",
          info.cap_pv && info.cap_hvm_directio ? " pv_directio" : "",
-         info.cap_hap ? " hap" : ""
+         info.cap_hap ? " hap" : "",
+         info.cap_iommu_hap_pt_share ? " iommu_hap_pt_share" : ""
         );
 
     vinfo = libxl_get_version_info(ctx);
diff --git a/xen/arch/arm/sysctl.c b/xen/arch/arm/sysctl.c
index f87944e847..6238c85be0 100644
--- a/xen/arch/arm/sysctl.c
+++ b/xen/arch/arm/sysctl.c
@@ -15,6 +15,9 @@
 void arch_do_physinfo(struct xen_sysctl_physinfo *pi)
 {
     pi->capabilities |= XEN_SYSCTL_PHYSCAP_hvm | XEN_SYSCTL_PHYSCAP_hap;
+
+    if ( iommu_enabled && iommu_hap_pt_share )
+        pi->capabilities |= XEN_SYSCTL_PHYSCAP_iommu_hap_pt_share;
 }
 
 long arch_do_sysctl(struct xen_sysctl *sysctl,
diff --git a/xen/arch/x86/sysctl.c b/xen/arch/x86/sysctl.c
index 5777a05ffc..c0adfbadb5 100644
--- a/xen/arch/x86/sysctl.c
+++ b/xen/arch/x86/sysctl.c
@@ -164,7 +164,12 @@ void arch_do_physinfo(struct xen_sysctl_physinfo *pi)
     if ( IS_ENABLED(CONFIG_PV) )
         pi->capabilities |= XEN_SYSCTL_PHYSCAP_pv;
     if ( hvm_hap_supported() )
+    {
         pi->capabilities |= XEN_SYSCTL_PHYSCAP_hap;
+
+        if ( iommu_enabled && iommu_hap_pt_share )
+            pi->capabilities |= XEN_SYSCTL_PHYSCAP_iommu_hap_pt_share;
+    }
 }
 
 long arch_do_sysctl(
diff --git a/xen/include/public/sysctl.h b/xen/include/public/sysctl.h
index d4b455619c..99bac0d33e 100644
--- a/xen/include/public/sysctl.h
+++ b/xen/include/public/sysctl.h
@@ -93,9 +93,13 @@ struct xen_sysctl_tbuf_op {
 /* The platform supports Hardware Assisted Paging. */
 #define _XEN_SYSCTL_PHYSCAP_hap          3
 #define XEN_SYSCTL_PHYSCAP_hap           (1u<<_XEN_SYSCTL_PHYSCAP_hap)
+/* The platform supports sharing of HAP page tables with the IOMMU. */
+#define _XEN_SYSCTL_PHYSCAP_iommu_hap_pt_share 4
+#define XEN_SYSCTL_PHYSCAP_iommu_hap_pt_share  \
+    (1u << _XEN_SYSCTL_PHYSCAP_iommu_hap_pt_share)
 
 /* Max XEN_SYSCTL_PHYSCAP_* constant.  Used for ABI checking. */
-#define XEN_SYSCTL_PHYSCAP_MAX XEN_SYSCTL_PHYSCAP_hap
+#define XEN_SYSCTL_PHYSCAP_MAX XEN_SYSCTL_PHYSCAP_iommu_hap_pt_share
 
 struct xen_sysctl_physinfo {
     uint32_t threads_per_core;
-- 
2.20.1.2.gb21ebb671


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