libxc: add MMIO hole size parameter to xc_hvm_build()

Add a parameter for the MMIO hole size when building a HVM domain.

This is useful for specifying a larger than normal MMIO hole to ensure
that no PCIe device's MMIO region overlaps with RAM in a guest's
physical address space.  This is needed on certain systems with PCIe
switches with a broken ACS capability.  On these systems, if a device
downstream of the switch attempts a DMA to a guest physical address
that overlaps with the MMIO region of another downstream device, then
the switch routes the transfer directly to the device and the read or
write never hits RAM.

Signed-off-by: David Vrabel <david.vrabel@citrix.com>
Acked-by: George Dunlap <george.dunlap@eu.citrix.com>
Committed-by: Ian Jackson <ian.jackson@eu.citrix.com>

1 files changed, 1 insertions, 0 deletions

diff --git a/tools/libxc/xenguest.h b/tools/libxc/xenguest.h
index f52ca74231..8d885d3133 100644
--- a/tools/libxc/xenguest.h
+++ b/tools/libxc/xenguest.h
@@ -174,6 +174,7 @@ int xc_linux_build_mem(xc_interface *xch,
 struct xc_hvm_build_args {
     uint64_t mem_size;           /* Memory size in bytes. */
     uint64_t mem_target;         /* Memory target in bytes. */
+    uint64_t mmio_size;          /* Size of the MMIO hole in bytes. */
     const char *image_file_name; /* File name of the image to load. */
 };