Avi Kivity wrote: > On 10/04/2009 10:59 AM, Jan Kiszka wrote: >> Hi, >> >> while preparing new IOCTLs to let user space query& set the yet >> unaccessible NMI states (pending and masked) I also came across the >> interrupt shadow masks. Unless I missed something I would say that we so >> far break them in the rare case that a migration happens right while any >> of them is asserted. So I guess I should extend my interface and stuff >> them in as well. >> >> Do we have more of such unaccessible states on x86 that could be >> included, too? Would be a good chance... >> > > There's some hidden state in the cpuid mechanism. I think we expose it > though (just don't use it in qemu). Do you have more details on this? > > The PDPTRs are hidden state that we should save/restore, though no sane > guest relies on them. A quick glance at SVM makes me think that those registered are not exposed there. So when keeping in mind that we may only help VMX guests, I think i makes even less sense to "fix" this, does it? > > I think we can lose information if we migrate during a SIPI > (sipi_vector), though that might be fixable without exposing it. Hmm, I see. But even it it's not fixable, such an extension would be an in-kernel irqchip thing. > > We'll might also lost debug traps. > > We drop pending exceptions; normally that's fine since they'll reinject > themselves, but MCE will not. So would it make sense and fix those two issues when we simply save and restore the pending exception? Jan
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