Re: [Xen-devel] [patch 1/2] HV: allow HVM virtual PICs to have their interrupt vector reprogrammed

[Keir Fraser <Keir.Fraser@xxxxxxxxxxxx>]

On 31/5/07 21:35, "Stephen C. Tweedie" <sct@xxxxxxxxxx> wrote:

> This turned out to be trivial to do.  I was just stalled for a while in
> testing it since it uncovered another regression --- Xen FV seems to
> have problem with the latest dynticks patches from FC7 kernels.
> 
> The new patch is much simpler; at the same time it's uglier in that it's
> an (even more) gross layering violation.
> 
> vmxassist does the rewriting of the guests vPIC vectors, so the HV
> *cannot* have any idea what vectors the guest actually intended to write
> when we go back to 32-bit mode.  However, vmxassist already hard-codes
> the vectors in several places: the 16-bit irq_bases are hard-coded to
> 0x08 and 0x70 in the trap bouncing code, and those bounce traps are
> hard-coded to live at 0x20 and 0x28.  If we are willing to extend that
> hard-coding into the hypervisor (but JUST the existing vmxassist-
> specific portion, not the general vPIC code), then the patch reduces to
> just a few lines, as below.

That's quite nasty, but I think that's okay in this case. I'll apply it.

 -- Keir



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