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| /openbmc/linux/arch/powerpc/kvm/ |
| H A D | book3s_64_mmu_hv.c | 891f1ebf Wed Sep 13 01:29:22 CDT 2017 Paul Mackerras <paulus@ozlabs.org> KVM: PPC: Book3S HV: Explicitly disable HPT operations on radix guests
This adds code to make sure that we don't try to access the
non-existent HPT for a radix guest using the htab file for the VM
in debugfs, a file descriptor obtained using the KVM_PPC_GET_HTAB_FD
ioctl, or via the KVM_PPC_RESIZE_HPT_{PREPARE,COMMIT} ioctls.
At present nothing bad happens if userspace does access these
interfaces on a radix guest, mostly because kvmppc_hpt_npte()
gives 0 for a radix guest, which in turn is because 1 << -4
comes out as 0 on POWER processors. However, that relies on
undefined behaviour, so it is better to be explicit about not
accessing the HPT for a radix guest.
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
891f1ebf Wed Sep 13 01:29:22 CDT 2017 Paul Mackerras <paulus@ozlabs.org> KVM: PPC: Book3S HV: Explicitly disable HPT operations on radix guests
This adds code to make sure that we don't try to access the
non-existent HPT for a radix guest using the htab file for the VM
in debugfs, a file descriptor obtained using the KVM_PPC_GET_HTAB_FD
ioctl, or via the KVM_PPC_RESIZE_HPT_{PREPARE,COMMIT} ioctls.
At present nothing bad happens if userspace does access these
interfaces on a radix guest, mostly because kvmppc_hpt_npte()
gives 0 for a radix guest, which in turn is because 1 << -4
comes out as 0 on POWER processors. However, that relies on
undefined behaviour, so it is better to be explicit about not
accessing the HPT for a radix guest.
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
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