arm64/cpufeatures/kvm: Add ARMv8.9 FEAT_ECBHB bits in ID_AA64MMFR1 register

commit e8cde32f upstream.

Enable ECBHB bits in ID_AA64MMFR1 register as per ARM DDI 0487K.a
specification.

When guest OS read ID_AA64MMFR1_EL1, kvm emulate this reg using
ftr_id_aa64mmfr1 and always return ID_AA64MMFR1_EL1.ECBHB=0 to guest.
It results in guest syscall jump to tramp ventry, which is not needed
in implementation with ID_AA64MMFR1_EL1.ECBHB=1.
Let's make the guest syscall process the same as the host.

Signed-off-by: Nianyao Tang <tangnianyao@huawei.com>
Link: https://lore.kernel.org/r/20240611122049.2758600-1-tangnianyao@huawei.com


Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
[ This fixes performance regressions introduced by commit 41179756
  ("arm64: errata: Add newer ARM cores to the
  spectre_bhb_loop_affected() lists") for guests running on neoverse v2
  hardware, which supports ECBHB. ]
Signed-off-by: Patrick Roy <roypat@amazon.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>