[Xen-devel] [PATCH 0/3] xen: msi support for Xen dom0

[Qing He <qing.he@xxxxxxxxx>]

This patch set adds support for msi in Xen dom0. It's based on the
pci notifier patches of Weidong Han (on rebase/pci branch) and
contains the following 3 patches.

        [PATCH 1/3] xen: make pci notifier work with booting devices
        [PATCH 2/3] xen: add msi support for dom0
        [PATCH 3/3] xen: re-enable msi (effectively revert bf89bc29)

One of the problem left is how to save/restore MSI across S3. Since
pci_restore_msi_state() now doesn't have any arch specific hook, the
code in arch/x86/ won't get a chance to run during S3 wakeup, so
write_msi_msg() is called instead of xen specific functions. One of
the possible solutions (and which I prefer) is to add something like
arch_pci_restore_msi, but that involves slightly changing
drivers/pci/msi.c, which probably needs more thinking and discussion.

An alternative is to trap and emulate any access to pci configuration
space. In that case, nothing in dom0 needs changing, and write_msi_msg
can be reused, but considerable logic may need to change in Xen
hypervisor.

Thanks,
Qing


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