set_fixmap_nocache()
    pci_mmcfg_read("device-B")
        pci_exp_set_dev_base()
            /* doesn't flush tlb */

But if cpus accessed the above order, the second pci_mmcfg_read() on
cpu0 doesn't flush the TLB, because "mmcfg_last_accessed_device" is
device-B.  So, second pci_mmcfg_read() on cpu0 accesses a device-A via
a previous TLB cache. This problem became the cause of several strange
behavior.

This patches fixes this situation by adds "mmcfg_last_accessed_cpu" check.

[ Alternatively, we could make a per-cpu mapping area or something. Not
  that it's probably worth it, but if we wanted to avoid all locking and
  instead just disable preemption, that would be the way to go. --Linus ]

Signed-off-by: OGAWA Hirofumi <hogawa@miraclelinux.com>
Signed-off-by: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
¬Þ‚)—Gx