[Xen-devel] [PATCH 3 of 4] qemu-xen: support PV on HVM MSI remapping

[stefano.stabellini@xxxxxxxxxxxxx]

If the guest enables an MSI passing 0 as vector number, then read the
address and use it as pirq number for the following mapping request to
Xen.

Signed-off-by: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>

diff --git a/hw/pt-msi.c b/hw/pt-msi.c
index b59b4fa..f0fb3e3 100644
--- a/hw/pt-msi.c
+++ b/hw/pt-msi.c
@@ -65,6 +65,7 @@ static void msix_set_enable(struct pt_dev *dev, int en)
 int pt_msi_setup(struct pt_dev *dev)
 {
     int pirq = -1;
+    uint8_t gvec = 0;
 
     if ( !(dev->msi->flags & MSI_FLAG_UNINIT) )
     {
@@ -72,6 +73,15 @@ int pt_msi_setup(struct pt_dev *dev)
         return -1;
     }
 
+    gvec = dev->msi->data & 0xFF;
+    if (!gvec) {
+        /* if gvec is 0, the guest is asking for a particular pirq that
+         * is passed as dest_id */
+        pirq = (dev->msi->addr_hi & 0xffffff00) |
+               ((dev->msi->addr_lo >> MSI_TARGET_CPU_SHIFT) & 0xff);
+        PT_LOG("pt_msi_setup requested pirq = %d\n", pirq);
+    }
+
     if ( xc_physdev_map_pirq_msi(xc_handle, domid, AUTO_ASSIGN, &pirq,
                                  PCI_DEVFN(dev->pci_dev->dev,
                                             ev->pci_dev->func),

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