virtio_pci: modern driver

Lightly tested against qemu.

One thing *not* implemented here is separate mappings
for descriptor/avail/used rings. That's nice to have,
will be done later after we have core support.

This also exposes the PCI layout to userspace, and
adds macros for PCI layout offsets:

QEMU wants it, so why not?  Trust, but verify.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

1 files changed, 4 insertions, 3 deletions

diff --git a/include/uapi/linux/virtio_pci.h b/include/uapi/linux/virtio_pci.h
index 4e054235358f..a2b2e1353e30 100644
--- a/include/uapi/linux/virtio_pci.h
+++ b/include/uapi/linux/virtio_pci.h
@@ -117,10 +117,11 @@ struct virtio_pci_cap {
         __u8 cap_vndr;          /* Generic PCI field: PCI_CAP_ID_VNDR */
         __u8 cap_next;          /* Generic PCI field: next ptr. */
         __u8 cap_len;           /* Generic PCI field: capability length */
-        __u8 type_and_bar;      /* Upper 3 bits: bar.
-                                 * Lower 3 is VIRTIO_PCI_CAP_*_CFG. */
+        __u8 cfg_type;          /* Identifies the structure. */
+        __u8 bar;               /* Where to find it. */
+        __u8 padding[3];        /* Pad to full dword. */
         __le32 offset;          /* Offset within bar. */
-        __le32 length;          /* Length. */
+        __le32 length;          /* Length of the structure, in bytes. */
 };
 
 #define VIRTIO_PCI_CAP_BAR_SHIFT        5