vmx: suppress posting interrupts when 'SN' is set

Currently, we don't support urgent interrupt, all interrupts
are recognized as non-urgent interrupt, so we cannot send
posted-interrupt when 'SN' is set.

Signed-off-by: Feng Wu <feng.wu@intel.com>
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
Acked-by: <kevin.tian@intel.com>

diff --git a/xen/arch/x86/hvm/vmx/vmx.c b/xen/arch/x86/hvm/vmx/vmx.c
index f7c5e4f9dc954289f26595188b4d33c39676926d..bc7d370e68201ce445e8e2c0d66727f90fce6743 100644 (file)
--- a/xen/arch/x86/hvm/vmx/vmx.c
+++ b/xen/arch/x86/hvm/vmx/vmx.c
@@ -1726,8 +1726,35 @@ static void vmx_deliver_posted_intr(struct vcpu *v, u8 vector)
          */
         pi_set_on(&v->arch.hvm_vmx.pi_desc);
     }
-    else if ( !pi_test_and_set_on(&v->arch.hvm_vmx.pi_desc) )
+    else
     {
+        struct pi_desc old, new, prev;
+
+        prev.control = v->arch.hvm_vmx.pi_desc.control;
+
+        do {
+            /*
+             * Currently, we don't support urgent interrupt, all
+             * interrupts are recognized as non-urgent interrupt,
+             * Besides that, if 'ON' is already set, no need to
+             * sent posted-interrupts notification event as well,
+             * according to hardware behavior.
+             */
+            if ( pi_test_sn(&prev) || pi_test_on(&prev) )
+            {
+                vcpu_kick(v);
+                return;
+            }
+
+            old.control = v->arch.hvm_vmx.pi_desc.control &
+                          ~((1 << POSTED_INTR_ON) | (1 << POSTED_INTR_SN));
+            new.control = v->arch.hvm_vmx.pi_desc.control |
+                          (1 << POSTED_INTR_ON);
+
+            prev.control = cmpxchg(&v->arch.hvm_vmx.pi_desc.control,
+                                   old.control, new.control);
+        } while ( prev.control != old.control );
+
         __vmx_deliver_posted_interrupt(v);
         return;
     }