[Xen-changelog] [xen staging] x86/IRQ: simplify pending EOI stack logic for internally used IRQs

[patchbot@xxxxxxx]

commit 53fd9dafeb5a7601bdfb090a631bafbbd3c84fe3
Author:     Jan Beulich <jbeulich@xxxxxxxx>
AuthorDate: Fri Dec 27 09:53:35 2019 +0100
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Fri Dec 27 09:53:35 2019 +0100

    x86/IRQ: simplify pending EOI stack logic for internally used IRQs
    
    In 5655ce8b1ec2 ("x86/IRQ: make internally used IRQs also honor the
    pending EOI stack") it was mentioned that both the check_eoi_deferral
    per-CPU variable and the cpu_has_pending_apic_eoi() were added just to
    have as little impact on existing behavior as possible, to reduce the
    risk of a last minute regression in 4.13.
    
    Upon closer inspection, dropping the variable is an option only if all
    callers of ->end() would assume the responsibility of also calling
    flush_ready_eoi(). Therefore only drop the cpu_has_pending_apic_eoi()
    guard now.
    
    Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
    Acked-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
---
 xen/arch/x86/irq.c | 17 ++++++-----------
 1 file changed, 6 insertions(+), 11 deletions(-)

diff --git a/xen/arch/x86/irq.c b/xen/arch/x86/irq.c
index 03e2f8edb6..9adad3ff04 100644
--- a/xen/arch/x86/irq.c
+++ b/xen/arch/x86/irq.c
@@ -1990,18 +1990,13 @@ void do_IRQ(struct cpu_user_regs *regs)
          * If higher priority vectors still have their EOIs pending, we may
          * not issue an EOI here, as this would EOI the highest priority one.
          */
-        if ( cpu_has_pending_apic_eoi() )
-        {
-            this_cpu(check_eoi_deferral) = true;
-            desc->handler->end(desc, vector);
-            this_cpu(check_eoi_deferral) = false;
-
-            spin_unlock(&desc->lock);
-            flush_ready_eoi();
-            goto out_no_unlock;
-        }
-
+        this_cpu(check_eoi_deferral) = true;
         desc->handler->end(desc, vector);
+        this_cpu(check_eoi_deferral) = false;
+
+        spin_unlock(&desc->lock);
+        flush_ready_eoi();
+        goto out_no_unlock;
     }
 
  out_no_end:
--
generated by git-patchbot for /home/xen/git/xen.git#staging

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