x86/domctl: restore all registers in arch_{get,set}_info_guest()

Commit 9f892f84c2 ("x86/domctl: Stop using XLAT_cpu_user_regs()")
converted memcpy() of the cpu_user_regs structure to explicit copy of
its fields. In the compat case, it intentionally missed few of them,
named in the commit message. But the 64bit case missed also r8-r15
registers, which was not intentional. This, at least, caused Linux
6.18.x crash when resuming PVH domU.

Fix it by adding missing assignments.

Fixes: 9f892f84c2 ("x86/domctl: Stop using XLAT_cpu_user_regs()")
Signed-off-by: Marek Marczykowski-Górecki <marmarek@invisiblethingslab.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Teddy Astie <teddy.astie@vates.tech>
master commit: bedbc17d84
master date: 2026-07-20 11:11:37 +0200

xen/arch/x86/domain.c

@@ -1280,6 +1280,14 @@ int arch_set_info_guest(
 
     if ( !compat )
     {
+        v->arch.user_regs.r15               = c.nat->user_regs.r15;
+        v->arch.user_regs.r14               = c.nat->user_regs.r14;
+        v->arch.user_regs.r13               = c.nat->user_regs.r13;
+        v->arch.user_regs.r12               = c.nat->user_regs.r12;
+        v->arch.user_regs.r11               = c.nat->user_regs.r11;
+        v->arch.user_regs.r10               = c.nat->user_regs.r10;
+        v->arch.user_regs.r9                = c.nat->user_regs.r9;
+        v->arch.user_regs.r8                = c.nat->user_regs.r8;
         v->arch.user_regs.rbx               = c.nat->user_regs.rbx;
         v->arch.user_regs.rcx               = c.nat->user_regs.rcx;
         v->arch.user_regs.rdx               = c.nat->user_regs.rdx;

xen/arch/x86/domctl.c

@@ -1440,6 +1440,14 @@ void arch_get_info_guest(struct vcpu *v, vcpu_guest_context_u c)
     if ( !compat )
     {
         /* Backing memory is pre-zeroed. */
+        c.nat->user_regs.r15               = v->arch.user_regs.r15;
+        c.nat->user_regs.r14               = v->arch.user_regs.r14;
+        c.nat->user_regs.r13               = v->arch.user_regs.r13;
+        c.nat->user_regs.r12               = v->arch.user_regs.r12;
+        c.nat->user_regs.r11               = v->arch.user_regs.r11;
+        c.nat->user_regs.r10               = v->arch.user_regs.r10;
+        c.nat->user_regs.r9                = v->arch.user_regs.r9;
+        c.nat->user_regs.r8                = v->arch.user_regs.r8;
         c.nat->user_regs.rbx               = v->arch.user_regs.rbx;
         c.nat->user_regs.rcx               = v->arch.user_regs.rcx;
         c.nat->user_regs.rdx               = v->arch.user_regs.rdx;