KVM: arm64: Allow vcpus running without HCR_EL2.FB

virt inclusion
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I4BLL0


CVE: NA

--------------------------------

As per ARM DDI 0487G.a, seting the HCR_EL2.FB (Force broadcast) bit causes
a given set of TLBI and IC instructions to be broadcast within the Inner
Shareable domain when executed from EL1 (if HCR_EL2.TGE is 0).

And people complain that this leads to bad performance when running guests
on Kunpeng920 which has 128 physical CPUs in the IS domain, especially in
the case where vcpus are pinned to physical CPUs, where we indeed don't
need broadcast invalidations.

Introduce a new cmdline parameter "kvm-arm.hcr_nofb" for users and setting
it at boot time allows all vcpus running without HCR_EL2.FB. Note that we
now have to nuke the whole vcpu context in the general case (when vcpu is
loaded on to the new physical CPU).

Co-developed-by: Nianyao Tang <tangnianyao@huawei.com>
Signed-off-by: Nianyao Tang <tangnianyao@huawei.com>
Signed-off-by: Zenghui Yu <yuzenghui@huawei.com>
Reviewed-by: Cheng Jian <cj.chengjian@huawei.com>
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>