[Xen-devel] [PATCH v10 6/6] passthrough/io: Fall back to remapping interrupt when we can't use VT-d PI

[Chao Gao <chao.gao@xxxxxxxxx>]

The current logic of using VT-d pi is when guest configurates the pirq's
destination vcpu to a single vcpu, the according IRTE is updated to
posted format. If the destination of the pirq is multiple vcpus, we just use
interrupt remapping. Obviously, we should fall back to remapping interrupt
when guest wrongly configurate destination of pirq or makes it have
multi-destination vcpus.

Signed-off-by: Chao Gao <chao.gao@xxxxxxxxx>
---
v10:
- Newly added

 xen/drivers/passthrough/io.c           | 9 +--------
 xen/drivers/passthrough/vtd/intremap.c | 2 +-
 2 files changed, 2 insertions(+), 9 deletions(-)

diff --git a/xen/drivers/passthrough/io.c b/xen/drivers/passthrough/io.c
index 37d9af6..be06b10 100644
--- a/xen/drivers/passthrough/io.c
+++ b/xen/drivers/passthrough/io.c
@@ -457,14 +457,7 @@ int pt_irq_create_bind(
 
         /* Use interrupt posting if it is supported. */
         if ( iommu_intpost )
-        {
-            if ( vcpu )
-                pi_update_irte(vcpu, info, pirq_dpci->gmsi.gvec);
-            else
-                dprintk(XENLOG_G_INFO,
-                        "%pv: deliver interrupt in remapping mode,gvec:%02x\n",
-                        vcpu, pirq_dpci->gmsi.gvec);
-        }
+            pi_update_irte(vcpu, info, pirq_dpci->gmsi.gvec);
 
         break;
     }
diff --git a/xen/drivers/passthrough/vtd/intremap.c 
b/xen/drivers/passthrough/vtd/intremap.c
index 342b45f..331c7d5 100644
--- a/xen/drivers/passthrough/vtd/intremap.c
+++ b/xen/drivers/passthrough/vtd/intremap.c
@@ -946,7 +946,7 @@ int pi_update_irte(const struct vcpu *v, const struct pirq 
*pirq,
 {
     struct irq_desc *desc;
     struct msi_desc *msi_desc;
-    const struct pi_desc *pi_desc = &v->arch.hvm_vmx.pi_desc;
+    const struct pi_desc *pi_desc = v ? &v->arch.hvm_vmx.pi_desc : NULL;
     int rc;
 
     desc = pirq_spin_lock_irq_desc(pirq, NULL);
-- 
1.8.3.1


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