[xen staging] x86/traps: remove smp_mb() ahead of IPI dispatch

[patchbot@xxxxxxx]

commit 6fec8fa1b57b4db88781f26bd2f084be5c4edd6a
Author:     Roger Pau Monne <roger.pau@xxxxxxxxxx>
AuthorDate: Thu May 22 09:23:33 2025 +0200
Commit:     Roger Pau Monne <roger.pau@xxxxxxxxxx>
CommitDate: Fri May 23 09:45:20 2025 +0200

    x86/traps: remove smp_mb() ahead of IPI dispatch
    
    The IPI dispatch functions already have the required barriers to ensure
    correct memory ordering.
    
    Note other callers of send_IPI_mask() don't use any barriers.
    
    No functional change intended.
    
    Reported-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
    Signed-off-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
    Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>
---
 xen/arch/x86/traps.c | 2 --
 1 file changed, 2 deletions(-)

diff --git a/xen/arch/x86/traps.c b/xen/arch/x86/traps.c
index c94779b4ad..22f2062932 100644
--- a/xen/arch/x86/traps.c
+++ b/xen/arch/x86/traps.c
@@ -785,8 +785,6 @@ void fatal_trap(const struct cpu_user_regs *regs, bool 
show_remote)
             cpumask_andnot(&show_state_mask, &cpu_online_map,
                            cpumask_of(smp_processor_id()));
             set_nmi_callback(nmi_show_execution_state);
-            /* Ensure new callback is set before sending out the NMI. */
-            smp_wmb();
             smp_send_nmi_allbutself();
 
             /* Wait at most 10ms for some other CPU to respond. */
--
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