Christoffer,
On 6/29/16 9:43 PM, Christoffer Dall wrote:
Doesn't this change carry the risk of KVM mapping a page (larger than
4K) containing other things than the GICV interface into the guest,
potentially breaking isolation of the VM from host hardware resources?
I still suspect the 64Kb long region is filled with 16 copies of first
4Kb of GICV, as Joel said in a thread two years ago when Marc introduced
sub-page alignment patch:
https://patches.linaro.org/patch/32191/
. So with that patch applied, a VM always boots on a 64Kb page granular
host, thanks to the multiple copies of the first part of GICV, but it'll
have a problem accessing the GICV_DIR register that is
placed at the second 4Kb of region mapped for GICV.
For the ACPI enabled systems, the check of physical address of the
virtual cpu interface is page aligned only works for 4Kb page granular
kernels, so the patch is still required, though I need to come up with
another patch that does map GICV to guest's physical address space
taking care of the offset in the presence of the new VGIC code.
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