[xen stable-4.16] x86: wire up VCPUOP_register_vcpu_time_memory_area for 32-bit guests

[patchbot@xxxxxxx]

commit 3f4da85ca8816f6617529c80850eaddd80ea0f1f
Author:     Jan Beulich <jbeulich@xxxxxxxx>
AuthorDate: Tue Oct 11 15:01:36 2022 +0200
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Tue Oct 11 15:01:36 2022 +0200

    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@xxxxxxxx>
    Acked-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
    master commit: b726541d94bd0a80b5864d17a2cd2e6d73a3fe0a
    master date: 2022-09-29 14:47:45 +0200
---
 xen/arch/x86/x86_64/domain.c | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/xen/arch/x86/x86_64/domain.c b/xen/arch/x86/x86_64/domain.c
index c46dccc25a..d51d993447 100644
--- 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;
--
generated by git-patchbot for /home/xen/git/xen.git#stable-4.16