Re: List of unaccessible x86 states

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



On 10/25/2009 06:45 PM, Alexander Graf wrote:
It's not. We can't use the guest memory for hsave because then the guest could break the l1 state, so a malicious hypervisor could break us.

Guest hsave should be used for storing guest state when switching into the nested guest, not host state. Host state is not part of the save/restore state in any case.


No it's not.

When going in an l2 guest, we need to save the l1 state in the hsave. Now if we'd use the l1 given hsave, the l2 guest could modify the hsave.

That means the l2 guest could rewrite the intercept bitmap to 0 and compromize the host.

L1 hsave stores the architected state saved by vmrun, e.g. cs.sel, next_rip, cr0, cr3, etc. The host intercept bitmap is not state since it is calculated from the L1 intercept bitmap and host code. Indeed it can be different from host to host even with the same guest state.

That's why we're storing the hsave data in a host allocated page.

Of course, we could save the whole hsave are off to the host on migeation...

Sorry, -ENOPARSE.

--
error compiling committee.c: too many arguments to function

--
To unsubscribe from this list: send the line "unsubscribe kvm" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html

[Index of Archives]     [KVM ARM]     [KVM ia64]     [KVM ppc]     [Virtualization Tools]     [Spice Development]     [Libvirt]     [Libvirt Users]     [Linux USB Devel]     [Linux Audio Users]     [Yosemite Questions]     [Linux Kernel]     [Linux SCSI]     [XFree86]
  Powered by Linux