[Xen-devel] [PATCH v10 5/6] passthrough/io: don't migrate pirq when it is delivered through VT-d PI

[Chao Gao <chao.gao@xxxxxxxxx>]

When a vCPU migrated to another pCPU, pt irqs binded to this vCPU also needed
migration. When VT-d PI is enabled, interrupt vector will be recorded to
a main memory resident data-structure and a notification whose destination
is decided by NDST is generated. NDST is properly adjusted during vCPU
migration so pirq directly injected to guest needn't be migrated.

This patch adds a indicator, @via_pi, to show whether the pt irq is delivered
through VT-d PI.

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

 xen/arch/x86/hvm/hvm.c       |  3 +++
 xen/drivers/passthrough/io.c | 15 +++++++++++----
 xen/include/xen/hvm/irq.h    |  1 +
 3 files changed, 15 insertions(+), 4 deletions(-)

diff --git a/xen/arch/x86/hvm/hvm.c b/xen/arch/x86/hvm/hvm.c
index ccfae4f..abbdab9 100644
--- a/xen/arch/x86/hvm/hvm.c
+++ b/xen/arch/x86/hvm/hvm.c
@@ -445,6 +445,9 @@ static int hvm_migrate_pirq(struct domain *d, struct 
hvm_pirq_dpci *pirq_dpci,
     struct vcpu *v = arg;
 
     if ( (pirq_dpci->flags & HVM_IRQ_DPCI_MACH_MSI) &&
+         (pirq_dpci->flags & HVM_IRQ_DPCI_GUEST_MSI) &&
+         /* Needn't migrate pirq if this pirq is delivered to guest directly.*/
+         (pirq_dpci->gmsi.via_pi != 1) &&
          (pirq_dpci->gmsi.dest_vcpu_id == v->vcpu_id) )
     {
         struct irq_desc *desc =
diff --git a/xen/drivers/passthrough/io.c b/xen/drivers/passthrough/io.c
index 080183e..37d9af6 100644
--- a/xen/drivers/passthrough/io.c
+++ b/xen/drivers/passthrough/io.c
@@ -365,6 +365,7 @@ int pt_irq_create_bind(
     {
         uint8_t dest, dest_mode, delivery_mode;
         int dest_vcpu_id;
+        const struct vcpu *vcpu = NULL;
 
         if ( !(pirq_dpci->flags & HVM_IRQ_DPCI_MAPPED) )
         {
@@ -441,6 +442,15 @@ int pt_irq_create_bind(
 
         dest_vcpu_id = hvm_girq_dest_2_vcpu_id(d, dest, dest_mode);
         pirq_dpci->gmsi.dest_vcpu_id = dest_vcpu_id;
+
+        pirq_dpci->gmsi.via_pi = 0;
+        if ( iommu_intpost )
+        {
+            vcpu = pi_find_dest_vcpu(d, dest, dest_mode, delivery_mode,
+                                     pirq_dpci->gmsi.gvec);
+            if ( vcpu )
+                pirq_dpci->gmsi.via_pi = 1;
+        }
         spin_unlock(&d->event_lock);
         if ( dest_vcpu_id >= 0 )
             hvm_migrate_pirqs(d->vcpu[dest_vcpu_id]);
@@ -448,11 +458,8 @@ int pt_irq_create_bind(
         /* Use interrupt posting if it is supported. */
         if ( iommu_intpost )
         {
-            const struct vcpu *vcpu = pi_find_dest_vcpu(d, dest, dest_mode,
-                                          delivery_mode, pirq_dpci->gmsi.gvec);
-
             if ( vcpu )
-                pi_update_irte( vcpu, info, pirq_dpci->gmsi.gvec );
+                pi_update_irte(vcpu, info, pirq_dpci->gmsi.gvec);
             else
                 dprintk(XENLOG_G_INFO,
                         "%pv: deliver interrupt in remapping mode,gvec:%02x\n",
diff --git a/xen/include/xen/hvm/irq.h b/xen/include/xen/hvm/irq.h
index d3f8623..ba74a31 100644
--- a/xen/include/xen/hvm/irq.h
+++ b/xen/include/xen/hvm/irq.h
@@ -63,6 +63,7 @@ struct hvm_gmsi_info {
     uint32_t gvec;
     uint32_t gflags;
     int dest_vcpu_id; /* -1 :multi-dest, non-negative: dest_vcpu_id */
+    bool via_pi; /* directly deliver to guest via VT-d PI? */
 };
 
 struct hvm_girq_dpci_mapping {
-- 
1.8.3.1


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