qemu/pci: check constant registers on load
Add "cmask" table of constant register masks: if a bit is not writeable
and is set in cmask table, this bit is checked on load. An attempt to
load an image that would change such a register causes load to fail.
Use this table to make sure that load does not modify registers that
guest can not change (directly or indirectly).
Note: we can't just assume that read-only registers never change,
because the guest could change a register indirectly.
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
diff --git a/hw/pci.h b/hw/pci.h
index d07477f..8b5edef 100644
--- a/hw/pci.h
+++ b/hw/pci.h
@@ -101,6 +101,7 @@
#define PCI_COMMAND_MASTER 0x4 /* Enable bus master */
#define PCI_STATUS 0x06 /* 16 bits */
#define PCI_REVISION_ID 0x08 /* 8 bits */
+#define PCI_CLASS_PROG 0x09 /* Reg. Level Programming Interface */
#define PCI_CLASS_DEVICE 0x0a /* Device class */
#define PCI_CACHE_LINE_SIZE 0x0c /* 8 bits */
#define PCI_LATENCY_TIMER 0x0d /* 8 bits */
@@ -159,6 +160,10 @@
/* PCI config space */
uint8_t config[PCI_CONFIG_SPACE_SIZE];
+ /* Used to enable config checks on load. Note that writeable bits are
+ * never checked even if set in cmask. */
+ uint8_t cmask[PCI_CONFIG_SPACE_SIZE];
+
/* Used to implement R/W bytes */
uint8_t wmask[PCI_CONFIG_SPACE_SIZE];
