intel-iommu: add Intel IOMMU emulation to q35 and add a machine option "iommu" as a switch

Add Intel IOMMU emulation to q35 chipset and expose it to the guest.
1. Add a machine option. Users can use "-machine iommu=on|off" in the command
line to enable/disable Intel IOMMU. The default is off.
2. Accroding to the machine option, q35 will initialize the Intel IOMMU and
use pci_setup_iommu() to setup q35_host_dma_iommu() as the IOMMU function for
the pci bus.
3. q35_host_dma_iommu() will return different address space according to the
bus_num and devfn of the device.

Signed-off-by: Le Tan <tamlokveer@gmail.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

1 files changed, 4 insertions, 0 deletions

diff --git a/vl.c b/vl.c
index b796c67e9d..cca012a7de 100644
--- a/vl.c
+++ b/vl.c
@@ -388,6 +388,10 @@ static QemuOptsList qemu_machine_opts = {
             .name = PC_MACHINE_MAX_RAM_BELOW_4G,
             .type = QEMU_OPT_SIZE,
             .help = "maximum ram below the 4G boundary (32bit boundary)",
+        },{
+            .name = "iommu",
+            .type = QEMU_OPT_BOOL,
+            .help = "Set on/off to enable/disable Intel IOMMU (VT-d)",
         },
         { /* End of list */ }
     },