[PATCH SERIES] enhanced PV on Xen HVM

[Stefano Stabellini]

Hi all,
this patch series is derived from an earlier version of Shen's "PV
extension of HVM" patch series.
It tries to achieve two goals:

- enable PV devices in Linux running in a Xen HVM domain;

- receive evtchns in place of interrupts to avoid expensive EOIs.

The main difference between the two patch series is the way the second
goals is achieved: in this patch series I am trying to reuse the same
code that is used in the Linux kernel to setup GSI to pirq mappings when
running as dom0.
In this case the GSIs that are being remapped correspond to emulated
interrupts, but Xen knows the difference and handles the two cases
separately.
It should be easy to use this mechanism also to map interrupts or MSIs
from pci passthrough devices with minimal changes to the Linux kernel.

The patch series consists of 5 patches, 1 for Xen and 4 for Linux; each
patch comes with a detailed description.

Any comment, critic or suggestion is very welcome.

Cheers,

Stefano
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[Stefano Stabellini]

On Tue, 2 Mar 2010, Stefano Stabellini wrote:
> Hi all,
> this patch series is derived from an earlier version of Shen's "PV
> extension of HVM" patch series.
> It tries to achieve two goals:
>
> - enable PV devices in Linux running in a Xen HVM domain;
>
> - receive evtchns in place of interrupts to avoid expensive EOIs.
>
> The main difference between the two patch series is the way the second
> goals is achieved: in this patch series I am trying to reuse the same
> code that is used in the Linux kernel to setup GSI to pirq mappings when
> running as dom0.
> In this case the GSIs that are being remapped correspond to emulated
> interrupts, but Xen knows the difference and handles the two cases
> separately.
> It should be easy to use this mechanism also to map interrupts or MSIs
> from pci passthrough devices with minimal changes to the Linux kernel.
>
> The patch series consists of 5 patches, 1 for Xen and 4 for Linux; each
> patch comes with a detailed description.
>
> Any comment, critic or suggestion is very welcome.
>

I should point out that the Linux side of the patch series is developed
against the branch "xen/dom0/apic-xiantao" of the pvops tree, that is
the master branch plus the recent apic rework.
Moreover it still needs few fixes: in particular the PV on HVM SMP
initialization code is exactly the same as in the last patch series from
Shen, therefore it doesn't address any of Jeremy's comments yet.