[RFC PATCH v6 10/43] altp2m: Add ARM support to do_altp2m_op

[Rose Spangler <Rose.Spangler@xxxxxxxxxxxxxx>]

This commit makes the minimum required changes necessary for do_altp2m_op
to compile on ARM. All altp2m commands in the switch statement are gated by
CONFIG_X86, with a default case of returning EOPNOTSUPP. This allows future
commits to move the #ifdef CONFIG_X86 down as support for ARM is added.

Additionally, a call to do_altp2m_op is added in the ARM HVMOP code.

This is commit 2/2 of the common do_altp2m_op phase.

Signed-off-by: Rose Spangler <Rose.Spangler@xxxxxxxxxxxxxx>
Signed-off-by: Sergej Proskurin <proskurin@xxxxxxxxxxxxx>
---
v6: Replaced patches 2 and 3 from v4/v5 patch set with this patch.

    Made HVM_PARAM_ALTP2M read-only, following the change to the x86
    implementation in commit 0291089f6ea8. The DOMCTL to enable altp2m on
    ARM is implemented in a later commit in this patch series.
---
 xen/arch/arm/hvm.c  |  9 +++++++++
 xen/common/altp2m.c | 29 ++++++++++++++---------------
 2 files changed, 23 insertions(+), 15 deletions(-)

diff --git a/xen/arch/arm/hvm.c b/xen/arch/arm/hvm.c
index 86e49bf47403..7c778795a280 100644
--- a/xen/arch/arm/hvm.c
+++ b/xen/arch/arm/hvm.c
@@ -5,6 +5,7 @@
  * Arch-specific hardware virtual machine abstractions.
  */
 
+#include <xen/altp2m.h>
 #include <xen/init.h>
 #include <xen/lib.h>
 #include <xen/errno.h>
@@ -23,6 +24,10 @@ static int hvm_allow_set_param(const struct domain *d, 
unsigned int param)
 {
     switch ( param )
     {
+        /* The following parameters are read-only. */
+    case HVM_PARAM_ALTP2M:
+        return -EEXIST;
+
         /*
          * The following parameters are intended for toolstack usage only.
          * They may not be set by the domain.
@@ -123,6 +128,10 @@ long do_hvm_op(unsigned long op, 
XEN_GUEST_HANDLE_PARAM(void) arg)
             rc = -EINVAL;
         break;
 
+    case HVMOP_altp2m:
+        rc = do_altp2m_op(arg);
+        break;
+
     default:
     {
         gdprintk(XENLOG_DEBUG, "HVMOP op=%lu: not implemented\n", op);
diff --git a/xen/common/altp2m.c b/xen/common/altp2m.c
index a43b3a3e34b3..6481fae1ed12 100644
--- a/xen/common/altp2m.c
+++ b/xen/common/altp2m.c
@@ -9,8 +9,10 @@
 
 #include <xsm/xsm.h>
 
-#ifdef CONFIG_X86
+#if defined(CONFIG_X86) && defined(CONFIG_HVM)
 #include <asm/hvm/nestedhvm.h>
+#endif
+
 /*
  * altp2m operations are envisioned as being used in several different
  * modes:
@@ -18,13 +20,13 @@
  * - external: All control and decisions are made by an external agent
  *   running domain 0.
  *
- * - internal: altp2m operations are used exclusively by an in-guest
- *   agent to protect itself from the guest kernel and in-guest
- *   attackers.
+ * - internal (x86 only): altp2m operations are used exclusively by an
+ *   in-guest agent to protect itself from the guest kernel and
+ *   in-guest attackers.
  *
- * - coordinated: An in-guest agent handles #VE and VMFUNCs locally,
- *   but makes requests of an agent running outside the domain for
- *   bigger changes (such as modifying altp2m entires).
+ * - coordinated (x86 only): An in-guest agent handles #VE and VMFUNCs
+ *   locally, but makes requests of an agent running outside the
+ *   domain for bigger changes (such as modifying altp2m entires).
  *
  * This corresponds to the three values for HVM_PARAM_ALTP2M
  * (external, mixed, limited). All three models have advantages and
@@ -97,7 +99,7 @@ int do_altp2m_op(
 
     if ( (a.cmd != HVMOP_altp2m_get_domain_state) &&
          (a.cmd != HVMOP_altp2m_set_domain_state) &&
-         !d->altp2m_active )
+         !altp2m_active(d) )
     {
         rc = -EOPNOTSUPP;
         goto out;
@@ -122,6 +124,7 @@ int do_altp2m_op(
 
     switch ( a.cmd )
     {
+#ifdef CONFIG_X86
     case HVMOP_altp2m_get_domain_state:
         a.u.domain_state.state = altp2m_active(d);
         rc = __copy_to_guest(arg, &a, 1) ? -EFAULT : 0;
@@ -394,9 +397,12 @@ int do_altp2m_op(
             rc = altp2m_set_view_visibility(d, idx, 
a.u.set_visibility.visible);
         break;
     }
+#endif /* CONFIG_X86 */
 
     default:
+#ifdef CONFIG_X86
         ASSERT_UNREACHABLE();
+#endif
         rc = -EOPNOTSUPP;
         break;
     }
@@ -406,13 +412,6 @@ int do_altp2m_op(
 
     return rc;
 }
-#else
-int do_altp2m_op(
-    XEN_GUEST_HANDLE_PARAM(void) arg)
-{
-    return -EOPNOTSUPP;
-}
-#endif
 
 /*
  * Local variables:
-- 
2.34.1