[PATCH for-4.{19,20}] xen/vpci: fix backport of 53859596c0d3

[Roger Pau Monne <roger.pau@xxxxxxxxxx>]

Commit 53859596c0d3 depends on the behavioral change introduced in
ee2eb6849d50 that inverted the initialization of the MSI-X and header vPCI
handlers.  53859596c0d3 requires the header to be initialized before MSI-X.

Change the order of initialization and adjust init_msix() to carve holes
for the MSI-X tables if necessary, since it will now run after the BARs
have been possibly mapped into the domain p2m.

Fixes: f9aea52a9747 ("vpci/msix: improve handling of bogus MSI-X capabilities")
Signed-off-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
---
Cc: jbeulich@xxxxxxxx
Cc: stewart.hildebrand@xxxxxxx
---
 xen/drivers/vpci/header.c | 2 +-
 xen/drivers/vpci/msix.c   | 9 +++++++--
 2 files changed, 8 insertions(+), 3 deletions(-)

diff --git a/xen/drivers/vpci/header.c b/xen/drivers/vpci/header.c
index 1f48f2aac64e..b002eb207243 100644
--- a/xen/drivers/vpci/header.c
+++ b/xen/drivers/vpci/header.c
@@ -1016,7 +1016,7 @@ static int cf_check init_header(struct pci_dev *pdev)
     pci_conf_write16(pdev->sbdf, PCI_COMMAND, cmd);
     return rc;
 }
-REGISTER_VPCI_INIT(init_header, VPCI_PRIORITY_MIDDLE);
+REGISTER_VPCI_INIT(init_header, VPCI_PRIORITY_HIGH);
 
 /*
  * Local variables:
diff --git a/xen/drivers/vpci/msix.c b/xen/drivers/vpci/msix.c
index faa7c1cd494a..94fb645377e5 100644
--- a/xen/drivers/vpci/msix.c
+++ b/xen/drivers/vpci/msix.c
@@ -792,9 +792,14 @@ static int cf_check init_msix(struct pci_dev *pdev)
     pdev->vpci->msix = msix;
     list_add(&msix->next, &d->arch.hvm.msix_tables);
 
-    return 0;
+    /*
+     * vPCI header initialization will have mapped the whole BAR into the
+     * p2m, as MSI-X capability was not yet initialized.  Crave a hole for
+     * the MSI-X table here, so that Xen can trap accesses.
+     */
+    return vpci_make_msix_hole(pdev);
 }
-REGISTER_VPCI_INIT(init_msix, VPCI_PRIORITY_HIGH);
+REGISTER_VPCI_INIT(init_msix, VPCI_PRIORITY_MIDDLE);
 
 /*
  * Local variables:
-- 
2.51.0