[PATCH v5 13/14] xen/arm: account IO handlers for emulated PCI MSI-X

[Oleksandr Andrushchenko <andr2000@gmail.com>]

From: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>

At the moment, we always allocate an extra 16 slots for IO handlers
(see MAX_IO_HANDLER). So while adding IO trap handlers for the emulated
MSI-X registers we need to explicitly tell that we have additional IO
handlers, so those are accounted.

Signed-off-by: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>

---
Cc: Julien Grall <julien@xen.org>
Cc: Stefano Stabellini <sstabellini@kernel.org>
---
This actually moved here from the part 2 of the prep work for PCI
passthrough on Arm as it seems to be the proper place for it.

New in v5
---
 xen/arch/arm/vpci.c | 15 ++++++++++++++-
 1 file changed, 14 insertions(+), 1 deletion(-)

diff --git a/xen/arch/arm/vpci.c b/xen/arch/arm/vpci.c
index 3d134f42d07e..902f8491e030 100644
--- a/xen/arch/arm/vpci.c
+++ b/xen/arch/arm/vpci.c
@@ -134,6 +134,8 @@ static int vpci_get_num_handlers_cb(struct domain *d,
 
 unsigned int domain_vpci_get_num_mmio_handlers(struct domain *d)
 {
+    unsigned int count;
+
     if ( !has_vpci(d) )
         return 0;
 
@@ -145,7 +147,18 @@ unsigned int domain_vpci_get_num_mmio_handlers(struct domain *d)
     }
 
     /* For a single emulated host bridge's configuration space. */
-    return 1;
+    count = 1;
+
+#ifdef CONFIG_HAS_PCI_MSI
+    /*
+     * There's a single MSI-X MMIO handler that deals with both PBA
+     * and MSI-X tables per each PCI device being passed through.
+     * Maximum number of emulated virtual devices is VPCI_MAX_VIRT_DEV.
+     */
+    count += VPCI_MAX_VIRT_DEV;
+#endif
+
+    return count;
 }
 
 /*
-- 
2.25.1