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Using the KVM API

Using the KVM API

Posted Sep 30, 2015 21:16 UTC (Wed) by luto (subscriber, #39314)
In reply to: Using the KVM API by pbonzini
Parent article: Using the KVM API

> Note that KVM used QEMU to handle the boot phase only in the very beginning; nowadays it uses vm86 mode or an in-kernel interpreter if unrestricted guest mode is unavailable. This avoids duplicating the emulation code between the kernel and userspace. Userspace doesn't know if you're running on a >=Westmere processor (or AMD, which has always had the equivalent of unrestricted mode--they called it "paged real mode"), or if you need to work around the limitations of the processor.

Please tell me that this is at least *guest* vm86 mode and not host vm86 mode.

Also, why does it care how the guest->host physical mappings are set up?

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Using the KVM API

Posted Oct 1, 2015 7:21 UTC (Thu) by pbonzini (subscriber, #60935) [Link]

Yes, it's still VMX, but the guest has CR0.PE=1 and EFLAGS.VM=1.

> Also, why does it care how the guest->host physical mappings are set up?

Can you explain your question better? Who is the subject?


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