[RFC PATCH 1/3] xen: Introduce "gpaddr_bits" field to XEN_SYSCTL_physinfo

[Oleksandr Tyshchenko <olekstysh@xxxxxxxxx>]

From: Oleksandr Tyshchenko <oleksandr_tyshchenko@xxxxxxxx>

We need to pass info about maximum supported guest address
space size to the toolstack on Arm in order to properly
calculate the base and size of the extended region (safe range)
for the guest. The extended region is unused address space which
could be safely used by domain for foreign/grant mappings on Arm.
The extended region itself will be handled by the subsequents
patch.

Use p2m_ipa_bits variable on Arm, the x86 equivalent is
hap_paddr_bits.

As we change the size of structure bump the interface version.

Suggested-by: Julien Grall <jgrall@xxxxxxxxxx>
Signed-off-by: Oleksandr Tyshchenko <oleksandr_tyshchenko@xxxxxxxx>
---
Changes since RFC:
   - update patch subject/description
   - replace arch-specific sub-struct with common gpaddr_bits
     field and update code to reflect that
---
 tools/include/libxl.h            | 7 +++++++
 tools/libs/light/libxl.c         | 2 ++
 tools/libs/light/libxl_types.idl | 2 ++
 xen/arch/arm/sysctl.c            | 2 ++
 xen/arch/x86/sysctl.c            | 2 ++
 xen/include/public/sysctl.h      | 3 ++-
 6 files changed, 17 insertions(+), 1 deletion(-)

diff --git a/tools/include/libxl.h b/tools/include/libxl.h
index b9ba16d..da44944 100644
--- a/tools/include/libxl.h
+++ b/tools/include/libxl.h
@@ -855,6 +855,13 @@ typedef struct libxl__ctx libxl_ctx;
  */
 #define LIBXL_HAVE_PHYSINFO_MAX_POSSIBLE_MFN 1
 
+ /*
+  * LIBXL_HAVE_PHYSINFO_GPADDR_BITS
+  *
+  * If this is defined, libxl_physinfo has a "gpaddr_bits" field.
+  */
+ #define LIBXL_HAVE_PHYSINFO_GPADDR_BITS 1
+
 /*
  * LIBXL_HAVE_DOMINFO_OUTSTANDING_MEMKB 1
  *
diff --git a/tools/libs/light/libxl.c b/tools/libs/light/libxl.c
index 204eb0b..c86624f 100644
--- a/tools/libs/light/libxl.c
+++ b/tools/libs/light/libxl.c
@@ -405,6 +405,8 @@ int libxl_get_physinfo(libxl_ctx *ctx, libxl_physinfo 
*physinfo)
     physinfo->cap_vmtrace =
         !!(xcphysinfo.capabilities & XEN_SYSCTL_PHYSCAP_vmtrace);
 
+    physinfo->gpaddr_bits = xcphysinfo.gpaddr_bits;
+
     GC_FREE;
     return 0;
 }
diff --git a/tools/libs/light/libxl_types.idl b/tools/libs/light/libxl_types.idl
index 3f9fff6..f7437e4 100644
--- a/tools/libs/light/libxl_types.idl
+++ b/tools/libs/light/libxl_types.idl
@@ -1061,6 +1061,8 @@ libxl_physinfo = Struct("physinfo", [
     ("cap_shadow", bool),
     ("cap_iommu_hap_pt_share", bool),
     ("cap_vmtrace", bool),
+
+    ("gpaddr_bits", uint32),
     ], dir=DIR_OUT)
 
 libxl_connectorinfo = Struct("connectorinfo", [
diff --git a/xen/arch/arm/sysctl.c b/xen/arch/arm/sysctl.c
index f87944e..91dca4f 100644
--- a/xen/arch/arm/sysctl.c
+++ b/xen/arch/arm/sysctl.c
@@ -15,6 +15,8 @@
 void arch_do_physinfo(struct xen_sysctl_physinfo *pi)
 {
     pi->capabilities |= XEN_SYSCTL_PHYSCAP_hvm | XEN_SYSCTL_PHYSCAP_hap;
+
+    pi->gpaddr_bits = p2m_ipa_bits;
 }
 
 long arch_do_sysctl(struct xen_sysctl *sysctl,
diff --git a/xen/arch/x86/sysctl.c b/xen/arch/x86/sysctl.c
index aff52a1..7b14865 100644
--- a/xen/arch/x86/sysctl.c
+++ b/xen/arch/x86/sysctl.c
@@ -135,6 +135,8 @@ void arch_do_physinfo(struct xen_sysctl_physinfo *pi)
         pi->capabilities |= XEN_SYSCTL_PHYSCAP_hap;
     if ( IS_ENABLED(CONFIG_SHADOW_PAGING) )
         pi->capabilities |= XEN_SYSCTL_PHYSCAP_shadow;
+
+    pi->gpaddr_bits = hap_paddr_bits;
 }
 
 long arch_do_sysctl(
diff --git a/xen/include/public/sysctl.h b/xen/include/public/sysctl.h
index 039ccf8..f53b42e 100644
--- a/xen/include/public/sysctl.h
+++ b/xen/include/public/sysctl.h
@@ -35,7 +35,7 @@
 #include "domctl.h"
 #include "physdev.h"
 
-#define XEN_SYSCTL_INTERFACE_VERSION 0x00000013
+#define XEN_SYSCTL_INTERFACE_VERSION 0x00000014
 
 /*
  * Read console content from Xen buffer ring.
@@ -120,6 +120,7 @@ struct xen_sysctl_physinfo {
     uint64_aligned_t outstanding_pages;
     uint64_aligned_t max_mfn; /* Largest possible MFN on this host */
     uint32_t hw_cap[8];
+    uint32_t gpaddr_bits;
 };
 
 /*
-- 
2.7.4