[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH] x86/VMX: sanitize VM86 TSS handling
At 01:18 -0700 on 15 Feb (1487121525), Jan Beulich wrote: > >>> On 14.02.17 at 18:33, <tim@xxxxxxx> wrote: > >> TBD: Do we really want to re-init the TSS every time we are about to > >> use it? > > > > No - I think we should init it when the guest writes the param(s) and > > leave it at that. Hvmloader marks it as reserved so the guest should > > know better than to write to it, and we can't protect it against all > > the possible ways the guest could break itself. > > > > If you do want to re-init it more often, then I think it would still > > be better to legacy guests' (lack of a) size limit once, when the guest > > writes the base param. > > The only problem with this being that at the time the base gets > written we don't know the size yet (nor whether the guest is > going to write it), and hence we don't know how must space to > initialize. The lower limit we enforce on the size (if being set) is > below the 128 byte default for old guests. Why not make the lower limit 128? I'd happily exchange simpler hypervisor code for the theoretical case of a guest that needs to run realmode code and cares about those few bytes. Cheers, Tim. _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx https://lists.xen.org/xen-devel
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