[RFC 16/55] KVM: arm64: Forward VM reg traps to the guest hypervisor

Christoffer Dall
2017-02-22T11:39:04Z

On Mon, Jan 09, 2017 at 01:24:12AM -0500, Jintack Lim wrote:
> Forward virtual memory register traps to the guest hypervisor
> if it has set corresponding bits to the virtual HCR_EL2.

I was a bit confused about the subject of this patch. I would recommend
calling it something like
"Respect virtul HCR_EL2.TVM and HCR_EL2.TRVM settings"

>
> Signed-off-by: Jintack Lim <jintack@cs.columbia.edu>
> ---
> arch/arm64/kvm/sys_regs.c | 20 ++++++++++++++++++++
> 1 file changed, 20 insertions(+)
>
> diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
> index b8e993a..0f5d21b 100644
> --- a/arch/arm64/kvm/sys_regs.c
> +++ b/arch/arm64/kvm/sys_regs.c
> @@ -90,6 +90,23 @@ static bool access_dcsw(struct kvm_vcpu *vcpu,
> return true;
> }
>
> +static bool forward_vm_traps(struct kvm_vcpu *vcpu, struct sys_reg_params *p)
> +{
> + u64 hcr_el2 = vcpu_el2_reg(vcpu, HCR_EL2);
> +
> + /* If this is a trap from the virtual EL2, the host handles */
> + if (vcpu_mode_el2(vcpu))
> + return false;
> +
> + /* If the guest wants to trap on R/W operation, forward this trap */
> + if ((hcr_el2 & HCR_TVM) && p->is_write)
> + return true;
> + else if ((hcr_el2 & HCR_TRVM) && !p->is_write)
> + return true;
> +
> + return false;
> +}
> +
> /*
> * Generic accessor for VM registers. Only called as long as HCR_TVM
> * is set. If the guest enables the MMU, we stop trapping the VM
> @@ -101,6 +118,9 @@ static bool access_vm_reg(struct kvm_vcpu *vcpu,
> {
> bool was_enabled = vcpu_has_cache_enabled(vcpu);
>
> + if (forward_vm_traps(vcpu, p))
> + return kvm_inject_nested_sync(vcpu, kvm_vcpu_get_hsr(vcpu));
> +
> BUG_ON(!vcpu_mode_el2(vcpu) && !p->is_write);
>
> if (!p->is_write) {
> --
> 1.9.1
>
>