Created attachment 330946 [details]
emulate accesses to PCI regs cf8/crc

Description of patch:

Emulate accesses to PCI window registers cf8/cfc to synchronise
with accesses by the hypervisor itself. All users of cf8/cfc go
through new access functions which take the appropriate spinlock.

Dom0 will access PCI window register cf8/cfc, now hypervisor also
accesses PCI configure space using PCI window register cf8/cfc for VT-d.
So it's possible that there is conflict, though the possibility is
very small. This patch emulates accesses to PCI window registers cf8/cfc
to synchronise with accesses by the hypervisor itself, then fixes the
issue.

BTW, there are still many changes on I/O port access between RHEL 5.4
and xen-unstable, the but they are not necessary for VT-d, we didn't
backport them, so you can find two difference between this patch and
xen-unstable: there are no check_guest_io_breakpoint() and
pv_post_outb_hook() in traps.c in RHEL 5.4.

Upstream Status: Accepted (CS 17441, 17465)