x86/entry: fix jump into restore_all_guest without %rbx correctly set

e047b8d went too far when limiting obtaining the vCPU pointer. While the code in ist_dispatch_done does indeed only need the vCPU pointer when PV32 is enabled, the !PV32 path will end up jumping into restore_all_guest which does require rbx == vCPU pointer. Fix by moving the fetching of the vCPU pointer to be done outside of the PV32 code block. Fixes: e047b8d ('x86/entry: replace two GET_CURRENT() uses') Reported-by: Edwin Torok <[email protected]> Signed-off-by: Roger Pau Monné <[email protected]> Reviewed-by: Andrew Cooper <[email protected]>
xen-project · Jan 26, 2024 · c378ff8 · c378ff8
1 parent dbdd7e8
commit c378ff8
Showing 1 changed file with 2 additions and 1 deletion.
diff --git a/xen/arch/x86/x86_64/entry.S b/xen/arch/x86/x86_64/entry.S
@@ -1139,8 +1139,9 @@ FUNC(handle_ist_exception)
         movl  $EVENT_CHECK_VECTOR,%edi
         call  send_IPI_self
 1:
-#ifdef CONFIG_PV32
+        /* For restore_all_guest. */
         mov   STACK_CPUINFO_FIELD(current_vcpu)(%r14), %rbx
+#ifdef CONFIG_PV32
         movq  VCPU_domain(%rbx),%rax
         cmpb  $0,DOMAIN_is_32bit_pv(%rax)
         je    restore_all_guest