virtio_pci: 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, 59 insertions, 1 deletions

diff --git a/drivers/virtio/virtio_pci_modern.c b/drivers/virtio/virtio_pci_modern.c
index a3d81013e0c2..b2e707ad81cf 100644
--- a/drivers/virtio/virtio_pci_modern.c
+++ b/drivers/virtio/virtio_pci_modern.c
@@ -464,9 +464,67 @@ static void virtio_pci_release_dev(struct device *_d)
         kfree(vp_dev);
 }
 
-/* TODO: validate the ABI statically. */
+/* This is part of the ABI.  Don't screw with it. */
 static inline void check_offsets(void)
 {
+        /* Note: disk space was harmed in compilation of this function. */
+        BUILD_BUG_ON(VIRTIO_PCI_CAP_VNDR !=
+                     offsetof(struct virtio_pci_cap, cap_vndr));
+        BUILD_BUG_ON(VIRTIO_PCI_CAP_NEXT !=
+                     offsetof(struct virtio_pci_cap, cap_next));
+        BUILD_BUG_ON(VIRTIO_PCI_CAP_LEN !=
+                     offsetof(struct virtio_pci_cap, cap_len));
+        BUILD_BUG_ON(VIRTIO_PCI_CAP_CFG_TYPE !=
+                     offsetof(struct virtio_pci_cap, cfg_type));
+        BUILD_BUG_ON(VIRTIO_PCI_CAP_BAR !=
+                     offsetof(struct virtio_pci_cap, bar));
+        BUILD_BUG_ON(VIRTIO_PCI_CAP_OFFSET !=
+                     offsetof(struct virtio_pci_cap, offset));
+        BUILD_BUG_ON(VIRTIO_PCI_CAP_LENGTH !=
+                     offsetof(struct virtio_pci_cap, length));
+        BUILD_BUG_ON(VIRTIO_PCI_NOTIFY_CAP_MULT !=
+                     offsetof(struct virtio_pci_notify_cap,
+                              notify_off_multiplier));
+        BUILD_BUG_ON(VIRTIO_PCI_COMMON_DFSELECT !=
+                     offsetof(struct virtio_pci_common_cfg,
+                              device_feature_select));
+        BUILD_BUG_ON(VIRTIO_PCI_COMMON_DF !=
+                     offsetof(struct virtio_pci_common_cfg, device_feature));
+        BUILD_BUG_ON(VIRTIO_PCI_COMMON_GFSELECT !=
+                     offsetof(struct virtio_pci_common_cfg,
+                              guest_feature_select));
+        BUILD_BUG_ON(VIRTIO_PCI_COMMON_GF !=
+                     offsetof(struct virtio_pci_common_cfg, guest_feature));
+        BUILD_BUG_ON(VIRTIO_PCI_COMMON_MSIX !=
+                     offsetof(struct virtio_pci_common_cfg, msix_config));
+        BUILD_BUG_ON(VIRTIO_PCI_COMMON_NUMQ !=
+                     offsetof(struct virtio_pci_common_cfg, num_queues));
+        BUILD_BUG_ON(VIRTIO_PCI_COMMON_STATUS !=
+                     offsetof(struct virtio_pci_common_cfg, device_status));
+        BUILD_BUG_ON(VIRTIO_PCI_COMMON_CFGGENERATION !=
+                     offsetof(struct virtio_pci_common_cfg, config_generation));
+        BUILD_BUG_ON(VIRTIO_PCI_COMMON_Q_SELECT !=
+                     offsetof(struct virtio_pci_common_cfg, queue_select));
+        BUILD_BUG_ON(VIRTIO_PCI_COMMON_Q_SIZE !=
+                     offsetof(struct virtio_pci_common_cfg, queue_size));
+        BUILD_BUG_ON(VIRTIO_PCI_COMMON_Q_MSIX !=
+                     offsetof(struct virtio_pci_common_cfg, queue_msix_vector));
+        BUILD_BUG_ON(VIRTIO_PCI_COMMON_Q_ENABLE !=
+                     offsetof(struct virtio_pci_common_cfg, queue_enable));
+        BUILD_BUG_ON(VIRTIO_PCI_COMMON_Q_NOFF !=
+                     offsetof(struct virtio_pci_common_cfg, queue_notify_off));
+        BUILD_BUG_ON(VIRTIO_PCI_COMMON_Q_DESCLO !=
+                     offsetof(struct virtio_pci_common_cfg, queue_desc_lo));
+        BUILD_BUG_ON(VIRTIO_PCI_COMMON_Q_DESCHI !=
+                     offsetof(struct virtio_pci_common_cfg, queue_desc_hi));
+        BUILD_BUG_ON(VIRTIO_PCI_COMMON_Q_AVAILLO !=
+                     offsetof(struct virtio_pci_common_cfg, queue_avail_lo));
+        BUILD_BUG_ON(VIRTIO_PCI_COMMON_Q_AVAILHI !=
+                     offsetof(struct virtio_pci_common_cfg, queue_avail_hi));
+        BUILD_BUG_ON(VIRTIO_PCI_COMMON_Q_USEDLO !=
+                     offsetof(struct virtio_pci_common_cfg, queue_used_lo));
+        BUILD_BUG_ON(VIRTIO_PCI_COMMON_Q_USEDHI !=
+                     offsetof(struct virtio_pci_common_cfg, queue_used_hi));
 }
 
 /* the PCI probing function */