x86: wire up VCPUOP_register_vcpu_time_memory_area for 32-bit guests

Forever sinced its introduction VCPUOP_register_vcpu_time_memory_area
was available only to native domains. Linux, for example, would attempt
to use it irrespective of guest bitness (including in its so called
PVHVM mode) as long as it finds XEN_PVCLOCK_TSC_STABLE_BIT set (which we
set only for clocksource=tsc, which in turn needs engaging via command
line option).

Fixes: a5d39947cb89 ("Allow guests to register secondary vcpu_time_info")
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Roger Pau Monné <roger.pau@citrix.com>
master commit: b726541d94bd0a80b5864d17a2cd2e6d73a3fe0a
master date: 2022-09-29 14:47:45 +0200

diff --git a/xen/arch/x86/x86_64/domain.c b/xen/arch/x86/x86_64/domain.c
index c46dccc25a544c9c6e95b17061babc73bccfb614..d51d9934479614db01ffc4a8917411634387658b 100644 (file)
--- a/xen/arch/x86/x86_64/domain.c
+++ b/xen/arch/x86/x86_64/domain.c
@@ -54,6 +54,26 @@ arch_compat_vcpu_op(
         break;
     }
 
+    case VCPUOP_register_vcpu_time_memory_area:
+    {
+        struct compat_vcpu_register_time_memory_area area = { .addr.p = 0 };
+
+        rc = -EFAULT;
+        if ( copy_from_guest(&area.addr.h, arg, 1) )
+            break;
+
+        if ( area.addr.h.c != area.addr.p ||
+             !compat_handle_okay(area.addr.h, 1) )
+            break;
+
+        rc = 0;
+        guest_from_compat_handle(v->arch.time_info_guest, area.addr.h);
+
+        force_update_vcpu_system_time(v);
+
+        break;
+    }
+
     case VCPUOP_get_physid:
         rc = arch_do_vcpu_op(cmd, v, arg);
         break;