Prohibit userspace from modifying values of ID registers. (Don't support configurable ID registers for 32bit EL1 guests) NOTE: The following patches will enable trapping disabled features only based on values of AArch64 ID registers for the guest expecting userspace to make AArch32 ID registers consistent with the AArch64 ones (Otherwise, it will be a userspace bug). Supporting 32bit EL1 guests will require that KVM will not enable trapping based on values of AArch64 ID registers (and should enable trapping based on the AArch32 ID registers when possible). Signed-off-by: Reiji Watanabe <reijiw@xxxxxxxxxx> --- arch/arm64/kvm/sys_regs.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c index b19e14a1206a..bc06570523f4 100644 --- a/arch/arm64/kvm/sys_regs.c +++ b/arch/arm64/kvm/sys_regs.c @@ -1537,6 +1537,10 @@ static int __set_id_reg(struct kvm_vcpu *vcpu, if (raz) return -EINVAL; + /* Don't allow to modify the register's value for the 32bit EL1 guest */ + if (test_bit(KVM_ARCH_FLAG_EL1_32BIT, &vcpu->kvm->arch.flags)) + return -EPERM; + /* * Don't allow to modify the register's value if the register doesn't * have the id_reg_desc. -- 2.36.0.rc0.470.gd361397f0d-goog
