[Xen-devel] [PATCH v2] xen arm/arm64: minor improvement in smp_send_call_function_mask()

[Anup Patel <anup.patel@xxxxxxxxxx>]

Currently, smp_send_call_function_mask() function implemented
by xen arm/arm64 will use IPI to call function on current CPU.

This means that current smp_send_call_function_mask() will do
the following on current CPU:
Trigger SGI for current CPU => Xen takes interrupt on current CPU
=> IPI interrupt handler will call smp_call_function_interrupt()

This patch improves the above by straight away calling
smp_call_function_interrupt() for current CPU. This is very
similar to smp_send_call_function_mask() implemented by Xen x86.

Changes since v1:
 - Drop the check protecting send_SGI_mask() call

Signed-off-by: Anup Patel <anup.patel@xxxxxxxxxx>
Signed-off-by: Pranavkumar Sawargaonkar <pranavkumar@xxxxxxxxxx>
Acked-by: Julien Grall <julien.grall@xxxxxxxxxx>
---
 xen/arch/arm/smp.c |   13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/xen/arch/arm/smp.c b/xen/arch/arm/smp.c
index 30203b8..917d490 100644
--- a/xen/arch/arm/smp.c
+++ b/xen/arch/arm/smp.c
@@ -19,7 +19,18 @@ void smp_send_event_check_mask(const cpumask_t *mask)
 
 void smp_send_call_function_mask(const cpumask_t *mask)
 {
-    send_SGI_mask(mask, GIC_SGI_CALL_FUNCTION);
+    cpumask_t target_mask;
+
+    cpumask_andnot(&target_mask, mask, cpumask_of(smp_processor_id()));
+
+    send_SGI_mask(&target_mask, GIC_SGI_CALL_FUNCTION);
+
+    if ( cpumask_test_cpu(smp_processor_id(), mask) )
+    {
+        local_irq_disable();
+        smp_call_function_interrupt();
+        local_irq_enable();
+    }
 }
 
 /*
-- 
1.7.9.5


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