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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH 3 of 7] Use a reserved pfn in the guest address space to store mem event ringsg
> At 09:44 -0800 on 01 Mar (1330595065), Andres Lagar-Cavilla wrote: >> > At 08:30 -0800 on 01 Mar (1330590637), Andres Lagar-Cavilla wrote: >> >> > At 07:47 +0000 on 01 Mar (1330588073), Ian Campbell wrote: >> >> >> > > Is there no scope for making these pages owned by the domain >> but >> >> not >> >> >> > > actually part of the P2M? We can cope with that for other >> types >> >> of >> >> >> magic >> >> >> > > page, can't we? >> >> > >> >> > It would need a new operation to map the ring into the tool that >> uses >> >> > it; normal map-foreign-page ops need a GFN. >> >> >> >> Actually, confirmed: we can call xc_domain_decrease_reservation on >> the >> >> ring after it's mapped by the helper. Guest won't get at it. Nothing >> >> breaks. >> > >> > But that would only work if: >> > - the helper always attaches before the guest gets to run; and >> >> The helper will ignore whatever contents there were on the page. And if >> the guest is out there poking in e820 reserved ranges, then the guest >> has >> it coming. Note that we've narrowed the window of "vulnerability". >> >> > - you never need to restart the helper. >> >> The helper can re-populate the pfn every time it starts. That's >> contemplated in the current patch series. In fact it can do it >> "atomically" by pausing the guest. > > OK, that seems good enough. Great, so I'll post this whole series again. I'll include the "remove ring from physmap" bits. And I'll add an Acked-by from Ian C for the tools bits. Cheers! Andres > > Tim. > _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
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