On 02/27/2011 05:52 PM, Gleb Natapov wrote:
>
> According to my reading of the code, if KVM_SET_TSS_ADDR is not
> invoked, the guest would fail both before and after the patch, yes?
>
Hmmm. Actually no. Before the patch guest that doesn't use KVM_SET_TSS_ADDR
will use the top of slot zero. Should I fix that (how?), or should we
drop support for those old guests?
I don't think we have a problem with older qemus, but perhaps we do with
non-qemu users. The API clearly requires the ioctl to be called, but I
don't think we can blame anyone for forgetting to do so, especially if
it worked silently.
The problem with using top of slot
zero is that this memory is available for guest use and we do not even
put it into e820 map as far as I see. Also there are patches floating
around that re-arrange memslots or even put them in a tree. They will
break old guests too.
Well, slot 0 still exists even if it is moved somewhere else.
Something we can do is put the tss slot just below the highest slot that
is still below 4G, and hope there is no mmio there. Once the user
issues KVM_SET_TSS_ADDR, use that. We'll have to keep juggling that
slot as the user creates more slots, icky.
--
error compiling committee.c: too many arguments to function
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